From: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Date: Mon, 29 Mar 2021 20:32:58 +0000 (-0400)
Subject: Refactoring: hide internal fields of ring buffer context
X-Git-Tag: v2.13.0-rc1~177
X-Git-Url: http://git.liburcu.org/?p=lttng-ust.git;a=commitdiff_plain;h=8936b6c0add7eb6706e0a1ca50e03c446dda4006

Refactoring: hide internal fields of ring buffer context

The public ring buffer context is allocated on the probe stack, but
contains many internal fields which are of no use to the probe. They
belong to that structure for the sake of passing information between
reserve, write, commit, strcpy, and other ring buffer callbacks.

Move those fields to a newly introduced private data structure, which is
allocated into a TLS stack belonging to the ring buffer client. It is
indexed with the TLS ring buffer nesting counter to allow recursive use
of the ring buffer (e.g. signal handlers).

While doing this, also move the "offset alignment" operation to the ring
buffer write callback. The alignment is now an additional parameter
expected by the write callback. Note that the strcpy and pstrcpy_pad
callbacks never need to do any alignment, so simply remove those
no-op alignments.

The event reserve callback does not need to have an explicit event id
parameter. It can fetch it from the client private data.

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Change-Id: I806c1b5de58446649fdfe433bfdc138b44e8f8af
---

diff --git a/include/lttng/ringbuffer-context.h b/include/lttng/ringbuffer-context.h
index e22fee19..577932df 100644
--- a/include/lttng/ringbuffer-context.h
+++ b/include/lttng/ringbuffer-context.h
@@ -22,14 +22,11 @@
 struct lttng_ust_lib_ring_buffer;
 struct lttng_ust_lib_ring_buffer_channel;
 struct lttng_ust_lib_ring_buffer_ctx;
+struct lttng_ust_lib_ring_buffer_ctx_private;
 
 /*
  * ring buffer context
  *
- * Context passed to lib_ring_buffer_reserve(), lib_ring_buffer_commit(),
- * lib_ring_buffer_try_discard_reserve(), lttng_ust_lib_ring_buffer_align_ctx() and
- * lib_ring_buffer_write().
- *
  * IMPORTANT: this structure is part of the ABI between the probe and
  * UST. Fields need to be only added at the end, never reordered, never
  * removed.
@@ -41,34 +38,16 @@ struct lttng_ust_lib_ring_buffer_ctx;
 struct lttng_ust_lib_ring_buffer_ctx {
 	uint32_t struct_size;			/* Size of this structure. */
 
-	/* input received by lib_ring_buffer_reserve(). */
-	struct lttng_ust_lib_ring_buffer_channel *chan; /* channel */
-	void *priv;				/* client private data */
+	void *client_priv;			/* Ring buffer client private data */
 	size_t data_size;			/* size of payload */
 	int largest_align;			/*
 						 * alignment of the largest element
 						 * in the payload
 						 */
-
-	/* output from lib_ring_buffer_reserve() */
-	int reserve_cpu;			/* processor id updated by the reserve */
-	size_t slot_size;			/* size of the reserved slot */
-	unsigned long buf_offset;		/* offset following the record header */
-	unsigned long pre_offset;		/*
-						 * Initial offset position _before_
-						 * the record is written. Positioned
-						 * prior to record header alignment
-						 * padding.
-						 */
-	uint64_t tsc;				/* time-stamp counter value */
-	unsigned int rflags;			/* reservation flags */
 	void *ip;				/* caller ip address */
 
-	struct lttng_ust_lib_ring_buffer *buf;	/*
-						 * buffer corresponding to processor id
-						 * for this channel
-						 */
-	struct lttng_ust_lib_ring_buffer_backend_pages *backend_pages;
+	/* Private ring buffer context, set by reserve callback. */
+	struct lttng_ust_lib_ring_buffer_ctx_private *priv;
 
 	/* End of base ABI. Fields below should be used after checking struct_size. */
 };
@@ -76,28 +55,26 @@ struct lttng_ust_lib_ring_buffer_ctx {
 /**
  * lttng_ust_lib_ring_buffer_ctx_init - initialize ring buffer context
  * @ctx: ring buffer context to initialize
- * @chan: channel
- * @priv: client private data
+ * @client_priv: client private data
  * @data_size: size of record data payload
  * @largest_align: largest alignment within data payload types
+ * @ip: caller ip address
  */
 static inline lttng_ust_notrace
 void lttng_ust_lib_ring_buffer_ctx_init(struct lttng_ust_lib_ring_buffer_ctx *ctx,
-			      struct lttng_ust_lib_ring_buffer_channel *chan,
-			      void *priv, size_t data_size, int largest_align);
+					void *client_priv, size_t data_size, int largest_align,
+					void *ip);
 static inline
 void lttng_ust_lib_ring_buffer_ctx_init(struct lttng_ust_lib_ring_buffer_ctx *ctx,
-			      struct lttng_ust_lib_ring_buffer_channel *chan,
-			      void *priv, size_t data_size, int largest_align)
+					void *client_priv, size_t data_size, int largest_align,
+					void *ip)
 {
 	ctx->struct_size = sizeof(struct lttng_ust_lib_ring_buffer_ctx);
-	ctx->chan = chan;
-	ctx->priv = priv;
+	ctx->client_priv = client_priv;
 	ctx->data_size = data_size;
-	ctx->reserve_cpu = -1;
 	ctx->largest_align = largest_align;
-	ctx->rflags = 0;
-	ctx->ip = 0;
+	ctx->ip = ip;
+	ctx->priv = NULL;
 }
 
 /*
@@ -147,19 +124,4 @@ unsigned int lttng_ust_lib_ring_buffer_align(size_t align_drift, size_t size_of_
 
 #endif
 
-/**
- * lttng_ust_lib_ring_buffer_align_ctx - Align context offset on "alignment"
- * @ctx: ring buffer context.
- */
-static inline lttng_ust_notrace
-void lttng_ust_lib_ring_buffer_align_ctx(struct lttng_ust_lib_ring_buffer_ctx *ctx,
-			   size_t alignment);
-static inline
-void lttng_ust_lib_ring_buffer_align_ctx(struct lttng_ust_lib_ring_buffer_ctx *ctx,
-			   size_t alignment)
-{
-	ctx->buf_offset += lttng_ust_lib_ring_buffer_align(ctx->buf_offset,
-						 alignment);
-}
-
 #endif /* _LTTNG_RING_BUFFER_CONTEXT_H */
diff --git a/include/lttng/ust-events.h b/include/lttng/ust-events.h
index 7090673d..108e7752 100644
--- a/include/lttng/ust-events.h
+++ b/include/lttng/ust-events.h
@@ -377,7 +377,6 @@ struct lttng_ust_event_recorder {
 	struct lttng_ust_event_common *parent;		/* Inheritance by aggregation. */
 	struct lttng_ust_event_recorder_private *priv;	/* Private event record interface */
 
-	unsigned int id;
 	struct lttng_ust_channel_buffer *chan;
 
 	/* End of base ABI. Fields below should be used after checking struct_size. */
@@ -446,11 +445,10 @@ struct lttng_ust_channel_buffer_ops {
 
 	struct lttng_ust_channel_buffer_ops_private *priv;	/* Private channel buffer ops interface */
 
-	int (*event_reserve)(struct lttng_ust_lib_ring_buffer_ctx *ctx,
-			     uint32_t event_id);
+	int (*event_reserve)(struct lttng_ust_lib_ring_buffer_ctx *ctx);
 	void (*event_commit)(struct lttng_ust_lib_ring_buffer_ctx *ctx);
 	void (*event_write)(struct lttng_ust_lib_ring_buffer_ctx *ctx,
-			const void *src, size_t len);
+			const void *src, size_t len, size_t alignment);
 	void (*event_strcpy)(struct lttng_ust_lib_ring_buffer_ctx *ctx,
 			const char *src, size_t len);
 	void (*event_pstrcpy_pad)(struct lttng_ust_lib_ring_buffer_ctx *ctx,
diff --git a/include/lttng/ust-tracepoint-event.h b/include/lttng/ust-tracepoint-event.h
index 77f03985..a5026733 100644
--- a/include/lttng/ust-tracepoint-event.h
+++ b/include/lttng/ust-tracepoint-event.h
@@ -688,24 +688,21 @@ size_t __event_get_align__##_provider##___##_name(_TP_ARGS_PROTO(_args))      \
 #define _ctf_integer_ext(_type, _item, _src, _byte_order, _base, _nowrite) \
 	{								\
 		_type __tmp = (_src);					\
-		lttng_ust_lib_ring_buffer_align_ctx(&__ctx, lttng_ust_rb_alignof(__tmp));\
-		__chan->ops->event_write(&__ctx, &__tmp, sizeof(__tmp));\
+		__chan->ops->event_write(&__ctx, &__tmp, sizeof(__tmp), lttng_ust_rb_alignof(__tmp));\
 	}
 
 #undef _ctf_float
 #define _ctf_float(_type, _item, _src, _nowrite)		        \
 	{								\
 		_type __tmp = (_src);					\
-		lttng_ust_lib_ring_buffer_align_ctx(&__ctx, lttng_ust_rb_alignof(__tmp));\
-		__chan->ops->event_write(&__ctx, &__tmp, sizeof(__tmp));\
+		__chan->ops->event_write(&__ctx, &__tmp, sizeof(__tmp), lttng_ust_rb_alignof(__tmp));\
 	}
 
 #undef _ctf_array_encoded
 #define _ctf_array_encoded(_type, _item, _src, _byte_order, _length,	\
 			_encoding, _nowrite, _elem_type_base)		\
-	lttng_ust_lib_ring_buffer_align_ctx(&__ctx, lttng_ust_rb_alignof(_type));	\
 	if (lttng_ust_string_encoding_##_encoding == lttng_ust_string_encoding_none) \
-		__chan->ops->event_write(&__ctx, _src, sizeof(_type) * (_length)); \
+		__chan->ops->event_write(&__ctx, _src, sizeof(_type) * (_length), lttng_ust_rb_alignof(_type)); \
 	else								\
 		__chan->ops->event_pstrcpy_pad(&__ctx, (const char *) (_src), _length); \
 
@@ -714,23 +711,19 @@ size_t __event_get_align__##_provider##___##_name(_TP_ARGS_PROTO(_args))      \
 			_src_length, _encoding, _nowrite, _elem_type_base) \
 	{								\
 		_length_type __tmpl = __stackvar.__dynamic_len[__dynamic_len_idx]; \
-		lttng_ust_lib_ring_buffer_align_ctx(&__ctx, lttng_ust_rb_alignof(_length_type));\
-		__chan->ops->event_write(&__ctx, &__tmpl, sizeof(_length_type));\
+		__chan->ops->event_write(&__ctx, &__tmpl, sizeof(_length_type), lttng_ust_rb_alignof(_length_type));\
 	}								\
-	lttng_ust_lib_ring_buffer_align_ctx(&__ctx, lttng_ust_rb_alignof(_type));	\
 	if (lttng_ust_string_encoding_##_encoding == lttng_ust_string_encoding_none) \
 		__chan->ops->event_write(&__ctx, _src,			\
-			sizeof(_type) * __get_dynamic_len(dest));	\
+			sizeof(_type) * __get_dynamic_len(dest), lttng_ust_rb_alignof(_type));	\
 	else								\
 		__chan->ops->event_pstrcpy_pad(&__ctx, (const char *) (_src), __get_dynamic_len(dest)); \
 
 #undef _ctf_string
-#define _ctf_string(_item, _src, _nowrite)			        \
+#define _ctf_string(_item, _src, _nowrite)					\
 	{									\
 		const char *__ctf_tmp_string =					\
 			((_src) ? (_src) : __LTTNG_UST_NULL_STRING);		\
-		lttng_ust_lib_ring_buffer_align_ctx(&__ctx,				\
-			lttng_ust_rb_alignof(*__ctf_tmp_string));			\
 		__chan->ops->event_strcpy(&__ctx, __ctf_tmp_string,		\
 			__get_dynamic_len(dest));				\
 	}
@@ -844,17 +837,13 @@ void __event_probe__##_provider##___##_name(_TP_ARGS_DATA_PROTO(_args))	      \
 		struct lttng_ust_event_recorder *__event_recorder = (struct lttng_ust_event_recorder *) __event->child; \
 		struct lttng_ust_channel_buffer *__chan = __event_recorder->chan; \
 		struct lttng_ust_lib_ring_buffer_ctx __ctx;		      \
-		struct lttng_ust_stack_ctx __lttng_ctx;			      \
 									      \
 		__event_len = __event_get_size__##_provider##___##_name(__stackvar.__dynamic_len, \
 			 _TP_ARGS_DATA_VAR(_args));			      \
 		__event_align = __event_get_align__##_provider##___##_name(_TP_ARGS_VAR(_args)); \
-		memset(&__lttng_ctx, 0, sizeof(__lttng_ctx));		      \
-		__lttng_ctx.struct_size = sizeof(struct lttng_ust_stack_ctx); \
-		__lttng_ctx.event_recorder = __event_recorder;		      \
-		lttng_ust_lib_ring_buffer_ctx_init(&__ctx, NULL, &__lttng_ctx, __event_len, __event_align); \
-		__ctx.ip = _TP_IP_PARAM(TP_IP_PARAM);			      \
-		__ret = __chan->ops->event_reserve(&__ctx, __event_recorder->id); \
+		lttng_ust_lib_ring_buffer_ctx_init(&__ctx, __event_recorder, __event_len, __event_align, \
+				_TP_IP_PARAM(TP_IP_PARAM));		      \
+		__ret = __chan->ops->event_reserve(&__ctx);		      \
 		if (__ret < 0)						      \
 			return;						      \
 		_fields							      \
diff --git a/liblttng-ust-ctl/ustctl.c b/liblttng-ust-ctl/ustctl.c
index a498f70c..40b3667b 100644
--- a/liblttng-ust-ctl/ustctl.c
+++ b/liblttng-ust-ctl/ustctl.c
@@ -1342,7 +1342,7 @@ int ustctl_write_metadata_to_channel(
 		reserve_len = min_t(size_t,
 				lttng_chan_buf->ops->priv->packet_avail_size(lttng_chan_buf),
 				len - pos);
-		lttng_ust_lib_ring_buffer_ctx_init(&ctx, rb_chan, NULL, reserve_len, sizeof(char));
+		lttng_ust_lib_ring_buffer_ctx_init(&ctx, rb_chan, reserve_len, sizeof(char), NULL);
 		/*
 		 * We don't care about metadata buffer's records lost
 		 * count, because we always retry here. Report error if
@@ -1351,7 +1351,7 @@ int ustctl_write_metadata_to_channel(
 		 */
 		waitret = wait_cond_interruptible_timeout(
 			({
-				ret = lttng_chan_buf->ops->event_reserve(&ctx, 0);
+				ret = lttng_chan_buf->ops->event_reserve(&ctx);
 				ret != -ENOBUFS || !ret;
 			}),
 			LTTNG_METADATA_TIMEOUT_MSEC);
@@ -1363,7 +1363,7 @@ int ustctl_write_metadata_to_channel(
 				ret = waitret;
 			goto end;
 		}
-		lttng_chan_buf->ops->event_write(&ctx, &str[pos], reserve_len);
+		lttng_chan_buf->ops->event_write(&ctx, &str[pos], reserve_len, 1);
 		lttng_chan_buf->ops->event_commit(&ctx);
 	}
 end:
@@ -1389,15 +1389,15 @@ ssize_t ustctl_write_one_packet_to_channel(
 	reserve_len = min_t(ssize_t,
 			lttng_chan_buf->ops->priv->packet_avail_size(lttng_chan_buf),
 			len);
-	lttng_ust_lib_ring_buffer_ctx_init(&ctx, rb_chan, NULL, reserve_len, sizeof(char));
-	ret = lttng_chan_buf->ops->event_reserve(&ctx, 0);
+	lttng_ust_lib_ring_buffer_ctx_init(&ctx, rb_chan, reserve_len, sizeof(char), NULL);
+	ret = lttng_chan_buf->ops->event_reserve(&ctx);
 	if (ret != 0) {
 		DBG("LTTng: event reservation failed");
 		assert(ret < 0);
 		reserve_len = ret;
 		goto end;
 	}
-	lttng_chan_buf->ops->event_write(&ctx, str, reserve_len);
+	lttng_chan_buf->ops->event_write(&ctx, str, reserve_len, 1);
 	lttng_chan_buf->ops->event_commit(&ctx);
 
 end:
diff --git a/liblttng-ust-java-agent/jni/common/lttng_ust_context.c b/liblttng-ust-java-agent/jni/common/lttng_ust_context.c
index 20fc113e..95679f53 100644
--- a/liblttng-ust-java-agent/jni/common/lttng_ust_context.c
+++ b/liblttng-ust-java-agent/jni/common/lttng_ust_context.c
@@ -154,18 +154,15 @@ static void record_cb(struct lttng_ust_ctx_field *field,
 	switch (jni_type) {
 	case JNI_TYPE_NULL:
 		sel_char = LTTNG_UST_DYNAMIC_TYPE_NONE;
-		lttng_ust_lib_ring_buffer_align_ctx(ctx, lttng_ust_rb_alignof(char));
-		lttng_chan_buf->ops->event_write(ctx, &sel_char, sizeof(sel_char));
+		lttng_chan_buf->ops->event_write(ctx, &sel_char, sizeof(sel_char), lttng_ust_rb_alignof(char));
 		break;
 	case JNI_TYPE_INTEGER:
 	{
 		int32_t v = jctx->value._integer;
 
 		sel_char = LTTNG_UST_DYNAMIC_TYPE_S32;
-		lttng_ust_lib_ring_buffer_align_ctx(ctx, lttng_ust_rb_alignof(char));
-		lttng_chan_buf->ops->event_write(ctx, &sel_char, sizeof(sel_char));
-		lttng_ust_lib_ring_buffer_align_ctx(ctx, lttng_ust_rb_alignof(v));
-		lttng_chan_buf->ops->event_write(ctx, &v, sizeof(v));
+		lttng_chan_buf->ops->event_write(ctx, &sel_char, sizeof(sel_char), lttng_ust_rb_alignof(char));
+		lttng_chan_buf->ops->event_write(ctx, &v, sizeof(v), lttng_ust_rb_alignof(v));
 		break;
 	}
 	case JNI_TYPE_LONG:
@@ -173,10 +170,8 @@ static void record_cb(struct lttng_ust_ctx_field *field,
 		int64_t v = jctx->value._long;
 
 		sel_char = LTTNG_UST_DYNAMIC_TYPE_S64;
-		lttng_ust_lib_ring_buffer_align_ctx(ctx, lttng_ust_rb_alignof(char));
-		lttng_chan_buf->ops->event_write(ctx, &sel_char, sizeof(sel_char));
-		lttng_ust_lib_ring_buffer_align_ctx(ctx, lttng_ust_rb_alignof(v));
-		lttng_chan_buf->ops->event_write(ctx, &v, sizeof(v));
+		lttng_chan_buf->ops->event_write(ctx, &sel_char, sizeof(sel_char), lttng_ust_rb_alignof(char));
+		lttng_chan_buf->ops->event_write(ctx, &v, sizeof(v), lttng_ust_rb_alignof(v));
 		break;
 	}
 	case JNI_TYPE_DOUBLE:
@@ -184,10 +179,8 @@ static void record_cb(struct lttng_ust_ctx_field *field,
 		double v = jctx->value._double;
 
 		sel_char = LTTNG_UST_DYNAMIC_TYPE_DOUBLE;
-		lttng_ust_lib_ring_buffer_align_ctx(ctx, lttng_ust_rb_alignof(char));
-		lttng_chan_buf->ops->event_write(ctx, &sel_char, sizeof(sel_char));
-		lttng_ust_lib_ring_buffer_align_ctx(ctx, lttng_ust_rb_alignof(v));
-		lttng_chan_buf->ops->event_write(ctx, &v, sizeof(v));
+		lttng_chan_buf->ops->event_write(ctx, &sel_char, sizeof(sel_char), lttng_ust_rb_alignof(char));
+		lttng_chan_buf->ops->event_write(ctx, &v, sizeof(v), lttng_ust_rb_alignof(v));
 		break;
 	}
 	case JNI_TYPE_FLOAT:
@@ -195,10 +188,8 @@ static void record_cb(struct lttng_ust_ctx_field *field,
 		float v = jctx->value._float;
 
 		sel_char = LTTNG_UST_DYNAMIC_TYPE_FLOAT;
-		lttng_ust_lib_ring_buffer_align_ctx(ctx, lttng_ust_rb_alignof(char));
-		lttng_chan_buf->ops->event_write(ctx, &sel_char, sizeof(sel_char));
-		lttng_ust_lib_ring_buffer_align_ctx(ctx, lttng_ust_rb_alignof(v));
-		lttng_chan_buf->ops->event_write(ctx, &v, sizeof(v));
+		lttng_chan_buf->ops->event_write(ctx, &sel_char, sizeof(sel_char), lttng_ust_rb_alignof(char));
+		lttng_chan_buf->ops->event_write(ctx, &v, sizeof(v), lttng_ust_rb_alignof(v));
 		break;
 	}
 	case JNI_TYPE_SHORT:
@@ -206,10 +197,8 @@ static void record_cb(struct lttng_ust_ctx_field *field,
 		int16_t v = jctx->value._short;
 
 		sel_char = LTTNG_UST_DYNAMIC_TYPE_S16;
-		lttng_ust_lib_ring_buffer_align_ctx(ctx, lttng_ust_rb_alignof(char));
-		lttng_chan_buf->ops->event_write(ctx, &sel_char, sizeof(sel_char));
-		lttng_ust_lib_ring_buffer_align_ctx(ctx, lttng_ust_rb_alignof(v));
-		lttng_chan_buf->ops->event_write(ctx, &v, sizeof(v));
+		lttng_chan_buf->ops->event_write(ctx, &sel_char, sizeof(sel_char), lttng_ust_rb_alignof(char));
+		lttng_chan_buf->ops->event_write(ctx, &v, sizeof(v), lttng_ust_rb_alignof(v));
 		break;
 	}
 	case JNI_TYPE_BYTE:
@@ -217,10 +206,8 @@ static void record_cb(struct lttng_ust_ctx_field *field,
 		char v = jctx->value._byte;
 
 		sel_char = LTTNG_UST_DYNAMIC_TYPE_S8;
-		lttng_ust_lib_ring_buffer_align_ctx(ctx, lttng_ust_rb_alignof(char));
-		lttng_chan_buf->ops->event_write(ctx, &sel_char, sizeof(sel_char));
-		lttng_ust_lib_ring_buffer_align_ctx(ctx, lttng_ust_rb_alignof(v));
-		lttng_chan_buf->ops->event_write(ctx, &v, sizeof(v));
+		lttng_chan_buf->ops->event_write(ctx, &sel_char, sizeof(sel_char), lttng_ust_rb_alignof(char));
+		lttng_chan_buf->ops->event_write(ctx, &v, sizeof(v), lttng_ust_rb_alignof(v));
 		break;
 	}
 	case JNI_TYPE_BOOLEAN:
@@ -228,10 +215,8 @@ static void record_cb(struct lttng_ust_ctx_field *field,
 		char v = jctx->value._boolean;
 
 		sel_char = LTTNG_UST_DYNAMIC_TYPE_S8;
-		lttng_ust_lib_ring_buffer_align_ctx(ctx, lttng_ust_rb_alignof(char));
-		lttng_chan_buf->ops->event_write(ctx, &sel_char, sizeof(sel_char));
-		lttng_ust_lib_ring_buffer_align_ctx(ctx, lttng_ust_rb_alignof(v));
-		lttng_chan_buf->ops->event_write(ctx, &v, sizeof(v));
+		lttng_chan_buf->ops->event_write(ctx, &sel_char, sizeof(sel_char), lttng_ust_rb_alignof(char));
+		lttng_chan_buf->ops->event_write(ctx, &v, sizeof(v), lttng_ust_rb_alignof(v));
 		break;
 	}
 	case JNI_TYPE_STRING:
@@ -244,10 +229,9 @@ static void record_cb(struct lttng_ust_ctx_field *field,
 			} else {
 				sel_char = LTTNG_UST_DYNAMIC_TYPE_NONE;
 			}
-			lttng_ust_lib_ring_buffer_align_ctx(ctx, lttng_ust_rb_alignof(char));
-			lttng_chan_buf->ops->event_write(ctx, &sel_char, sizeof(sel_char));
+			lttng_chan_buf->ops->event_write(ctx, &sel_char, sizeof(sel_char), lttng_ust_rb_alignof(char));
 			if (str) {
-				lttng_chan_buf->ops->event_write(ctx, str, strlen(str) + 1);
+				lttng_chan_buf->ops->event_write(ctx, str, strlen(str) + 1, 1);
 			}
 			break;
 	}
diff --git a/liblttng-ust/lttng-context-cgroup-ns.c b/liblttng-ust/lttng-context-cgroup-ns.c
index 8ac91c4f..d25a9b13 100644
--- a/liblttng-ust/lttng-context-cgroup-ns.c
+++ b/liblttng-ust/lttng-context-cgroup-ns.c
@@ -108,8 +108,8 @@ void cgroup_ns_record(struct lttng_ust_ctx_field *field,
 	ino_t cgroup_ns;
 
 	cgroup_ns = get_cgroup_ns();
-	lttng_ust_lib_ring_buffer_align_ctx(ctx, lttng_ust_rb_alignof(cgroup_ns));
-	chan->ops->event_write(ctx, &cgroup_ns, sizeof(cgroup_ns));
+	chan->ops->event_write(ctx, &cgroup_ns, sizeof(cgroup_ns),
+			lttng_ust_rb_alignof(cgroup_ns));
 }
 
 static
diff --git a/liblttng-ust/lttng-context-cpu-id.c b/liblttng-ust/lttng-context-cpu-id.c
index e518314d..b3c64974 100644
--- a/liblttng-ust/lttng-context-cpu-id.c
+++ b/liblttng-ust/lttng-context-cpu-id.c
@@ -42,8 +42,7 @@ void cpu_id_record(struct lttng_ust_ctx_field *field,
 	int cpu;
 
 	cpu = lttng_ust_get_cpu();
-	lttng_ust_lib_ring_buffer_align_ctx(ctx, lttng_ust_rb_alignof(cpu));
-	chan->ops->event_write(ctx, &cpu, sizeof(cpu));
+	chan->ops->event_write(ctx, &cpu, sizeof(cpu), lttng_ust_rb_alignof(cpu));
 }
 
 static
diff --git a/liblttng-ust/lttng-context-ip.c b/liblttng-ust/lttng-context-ip.c
index 29ca29e2..4f4ef632 100644
--- a/liblttng-ust/lttng-context-ip.c
+++ b/liblttng-ust/lttng-context-ip.c
@@ -35,8 +35,7 @@ void ip_record(struct lttng_ust_ctx_field *field,
 	void *ip;
 
 	ip = ctx->ip;
-	lttng_ust_lib_ring_buffer_align_ctx(ctx, lttng_ust_rb_alignof(ip));
-	chan->ops->event_write(ctx, &ip, sizeof(ip));
+	chan->ops->event_write(ctx, &ip, sizeof(ip), lttng_ust_rb_alignof(ip));
 }
 
 int lttng_add_ip_to_ctx(struct lttng_ust_ctx **ctx)
diff --git a/liblttng-ust/lttng-context-ipc-ns.c b/liblttng-ust/lttng-context-ipc-ns.c
index 9988684f..a08b9a02 100644
--- a/liblttng-ust/lttng-context-ipc-ns.c
+++ b/liblttng-ust/lttng-context-ipc-ns.c
@@ -107,8 +107,7 @@ void ipc_ns_record(struct lttng_ust_ctx_field *field,
 	ino_t ipc_ns;
 
 	ipc_ns = get_ipc_ns();
-	lttng_ust_lib_ring_buffer_align_ctx(ctx, lttng_ust_rb_alignof(ipc_ns));
-	chan->ops->event_write(ctx, &ipc_ns, sizeof(ipc_ns));
+	chan->ops->event_write(ctx, &ipc_ns, sizeof(ipc_ns), lttng_ust_rb_alignof(ipc_ns));
 }
 
 static
diff --git a/liblttng-ust/lttng-context-mnt-ns.c b/liblttng-ust/lttng-context-mnt-ns.c
index 895dfe66..8a2b7e86 100644
--- a/liblttng-ust/lttng-context-mnt-ns.c
+++ b/liblttng-ust/lttng-context-mnt-ns.c
@@ -90,8 +90,7 @@ void mnt_ns_record(struct lttng_ust_ctx_field *field,
 	ino_t mnt_ns;
 
 	mnt_ns = get_mnt_ns();
-	lttng_ust_lib_ring_buffer_align_ctx(ctx, lttng_ust_rb_alignof(mnt_ns));
-	chan->ops->event_write(ctx, &mnt_ns, sizeof(mnt_ns));
+	chan->ops->event_write(ctx, &mnt_ns, sizeof(mnt_ns), lttng_ust_rb_alignof(mnt_ns));
 }
 
 static
diff --git a/liblttng-ust/lttng-context-net-ns.c b/liblttng-ust/lttng-context-net-ns.c
index d1bf7d5a..655759ac 100644
--- a/liblttng-ust/lttng-context-net-ns.c
+++ b/liblttng-ust/lttng-context-net-ns.c
@@ -107,8 +107,7 @@ void net_ns_record(struct lttng_ust_ctx_field *field,
 	ino_t net_ns;
 
 	net_ns = get_net_ns();
-	lttng_ust_lib_ring_buffer_align_ctx(ctx, lttng_ust_rb_alignof(net_ns));
-	chan->ops->event_write(ctx, &net_ns, sizeof(net_ns));
+	chan->ops->event_write(ctx, &net_ns, sizeof(net_ns), lttng_ust_rb_alignof(net_ns));
 }
 
 static
diff --git a/liblttng-ust/lttng-context-perf-counters.c b/liblttng-ust/lttng-context-perf-counters.c
index 3a00a7fa..94f4e95d 100644
--- a/liblttng-ust/lttng-context-perf-counters.c
+++ b/liblttng-ust/lttng-context-perf-counters.c
@@ -445,8 +445,7 @@ void perf_counter_record(struct lttng_ust_ctx_field *field,
 	uint64_t value;
 
 	value = wrapper_perf_counter_read(field);
-	lttng_ust_lib_ring_buffer_align_ctx(ctx, lttng_ust_rb_alignof(value));
-	chan->ops->event_write(ctx, &value, sizeof(value));
+	chan->ops->event_write(ctx, &value, sizeof(value), lttng_ust_rb_alignof(value));
 }
 
 static
diff --git a/liblttng-ust/lttng-context-pid-ns.c b/liblttng-ust/lttng-context-pid-ns.c
index 4bdd95ac..21dae9a8 100644
--- a/liblttng-ust/lttng-context-pid-ns.c
+++ b/liblttng-ust/lttng-context-pid-ns.c
@@ -93,8 +93,7 @@ void pid_ns_record(struct lttng_ust_ctx_field *field,
 	ino_t pid_ns;
 
 	pid_ns = get_pid_ns();
-	lttng_ust_lib_ring_buffer_align_ctx(ctx, lttng_ust_rb_alignof(pid_ns));
-	chan->ops->event_write(ctx, &pid_ns, sizeof(pid_ns));
+	chan->ops->event_write(ctx, &pid_ns, sizeof(pid_ns), lttng_ust_rb_alignof(pid_ns));
 }
 
 static
diff --git a/liblttng-ust/lttng-context-procname.c b/liblttng-ust/lttng-context-procname.c
index 00a79355..2e2c7fa2 100644
--- a/liblttng-ust/lttng-context-procname.c
+++ b/liblttng-ust/lttng-context-procname.c
@@ -78,7 +78,7 @@ void procname_record(struct lttng_ust_ctx_field *field,
 	char *procname;
 
 	procname = wrapper_getprocname();
-	chan->ops->event_write(ctx, procname, LTTNG_UST_ABI_PROCNAME_LEN);
+	chan->ops->event_write(ctx, procname, LTTNG_UST_ABI_PROCNAME_LEN, 1);
 }
 
 static
diff --git a/liblttng-ust/lttng-context-pthread-id.c b/liblttng-ust/lttng-context-pthread-id.c
index d26cf908..b6aa5470 100644
--- a/liblttng-ust/lttng-context-pthread-id.c
+++ b/liblttng-ust/lttng-context-pthread-id.c
@@ -34,8 +34,7 @@ void pthread_id_record(struct lttng_ust_ctx_field *field,
 	unsigned long pthread_id;
 
 	pthread_id = (unsigned long) pthread_self();
-	lttng_ust_lib_ring_buffer_align_ctx(ctx, lttng_ust_rb_alignof(pthread_id));
-	chan->ops->event_write(ctx, &pthread_id, sizeof(pthread_id));
+	chan->ops->event_write(ctx, &pthread_id, sizeof(pthread_id), lttng_ust_rb_alignof(pthread_id));
 }
 
 static
diff --git a/liblttng-ust/lttng-context-time-ns.c b/liblttng-ust/lttng-context-time-ns.c
index ef5ae414..b9d07d08 100644
--- a/liblttng-ust/lttng-context-time-ns.c
+++ b/liblttng-ust/lttng-context-time-ns.c
@@ -106,8 +106,7 @@ void time_ns_record(struct lttng_ust_ctx_field *field,
 	ino_t time_ns;
 
 	time_ns = get_time_ns();
-	lttng_ust_lib_ring_buffer_align_ctx(ctx, lttng_ust_rb_alignof(time_ns));
-	chan->ops->event_write(ctx, &time_ns, sizeof(time_ns));
+	chan->ops->event_write(ctx, &time_ns, sizeof(time_ns), lttng_ust_rb_alignof(time_ns));
 }
 
 static
diff --git a/liblttng-ust/lttng-context-user-ns.c b/liblttng-ust/lttng-context-user-ns.c
index 3da97f0b..f42ac079 100644
--- a/liblttng-ust/lttng-context-user-ns.c
+++ b/liblttng-ust/lttng-context-user-ns.c
@@ -90,8 +90,7 @@ void user_ns_record(struct lttng_ust_ctx_field *field,
 	ino_t user_ns;
 
 	user_ns = get_user_ns();
-	lttng_ust_lib_ring_buffer_align_ctx(ctx, lttng_ust_rb_alignof(user_ns));
-	chan->ops->event_write(ctx, &user_ns, sizeof(user_ns));
+	chan->ops->event_write(ctx, &user_ns, sizeof(user_ns), lttng_ust_rb_alignof(user_ns));
 }
 
 static
diff --git a/liblttng-ust/lttng-context-uts-ns.c b/liblttng-ust/lttng-context-uts-ns.c
index a410c264..f8b0bd8c 100644
--- a/liblttng-ust/lttng-context-uts-ns.c
+++ b/liblttng-ust/lttng-context-uts-ns.c
@@ -108,8 +108,7 @@ void uts_ns_record(struct lttng_ust_ctx_field *field,
 	ino_t uts_ns;
 
 	uts_ns = get_uts_ns();
-	lttng_ust_lib_ring_buffer_align_ctx(ctx, lttng_ust_rb_alignof(uts_ns));
-	chan->ops->event_write(ctx, &uts_ns, sizeof(uts_ns));
+	chan->ops->event_write(ctx, &uts_ns, sizeof(uts_ns), lttng_ust_rb_alignof(uts_ns));
 }
 
 static
diff --git a/liblttng-ust/lttng-context-vegid.c b/liblttng-ust/lttng-context-vegid.c
index da853040..a6306f3c 100644
--- a/liblttng-ust/lttng-context-vegid.c
+++ b/liblttng-ust/lttng-context-vegid.c
@@ -79,8 +79,7 @@ void vegid_record(struct lttng_ust_ctx_field *field,
 	gid_t vegid;
 
 	vegid = get_vegid();
-	lttng_ust_lib_ring_buffer_align_ctx(ctx, lttng_ust_rb_alignof(vegid));
-	chan->ops->event_write(ctx, &vegid, sizeof(vegid));
+	chan->ops->event_write(ctx, &vegid, sizeof(vegid), lttng_ust_rb_alignof(vegid));
 }
 
 static
diff --git a/liblttng-ust/lttng-context-veuid.c b/liblttng-ust/lttng-context-veuid.c
index db60322d..d5ef5199 100644
--- a/liblttng-ust/lttng-context-veuid.c
+++ b/liblttng-ust/lttng-context-veuid.c
@@ -79,8 +79,7 @@ void veuid_record(struct lttng_ust_ctx_field *field,
 	uid_t veuid;
 
 	veuid = get_veuid();
-	lttng_ust_lib_ring_buffer_align_ctx(ctx, lttng_ust_rb_alignof(veuid));
-	chan->ops->event_write(ctx, &veuid, sizeof(veuid));
+	chan->ops->event_write(ctx, &veuid, sizeof(veuid), lttng_ust_rb_alignof(veuid));
 }
 
 static
diff --git a/liblttng-ust/lttng-context-vgid.c b/liblttng-ust/lttng-context-vgid.c
index ac298ae2..78316139 100644
--- a/liblttng-ust/lttng-context-vgid.c
+++ b/liblttng-ust/lttng-context-vgid.c
@@ -79,8 +79,7 @@ void vgid_record(struct lttng_ust_ctx_field *field,
 	gid_t vgid;
 
 	vgid = get_vgid();
-	lttng_ust_lib_ring_buffer_align_ctx(ctx, lttng_ust_rb_alignof(vgid));
-	chan->ops->event_write(ctx, &vgid, sizeof(vgid));
+	chan->ops->event_write(ctx, &vgid, sizeof(vgid), lttng_ust_rb_alignof(vgid));
 }
 
 static
diff --git a/liblttng-ust/lttng-context-vpid.c b/liblttng-ust/lttng-context-vpid.c
index c77468c1..43685960 100644
--- a/liblttng-ust/lttng-context-vpid.c
+++ b/liblttng-ust/lttng-context-vpid.c
@@ -62,8 +62,7 @@ void vpid_record(struct lttng_ust_ctx_field *field,
 {
 	pid_t vpid = wrapper_getvpid();
 
-	lttng_ust_lib_ring_buffer_align_ctx(ctx, lttng_ust_rb_alignof(vpid));
-	chan->ops->event_write(ctx, &vpid, sizeof(vpid));
+	chan->ops->event_write(ctx, &vpid, sizeof(vpid), lttng_ust_rb_alignof(vpid));
 }
 
 static
diff --git a/liblttng-ust/lttng-context-vsgid.c b/liblttng-ust/lttng-context-vsgid.c
index 87e11f85..d2ac2a70 100644
--- a/liblttng-ust/lttng-context-vsgid.c
+++ b/liblttng-ust/lttng-context-vsgid.c
@@ -83,8 +83,7 @@ void vsgid_record(struct lttng_ust_ctx_field *field,
 	gid_t vsgid;
 
 	vsgid = get_vsgid();
-	lttng_ust_lib_ring_buffer_align_ctx(ctx, lttng_ust_rb_alignof(vsgid));
-	chan->ops->event_write(ctx, &vsgid, sizeof(vsgid));
+	chan->ops->event_write(ctx, &vsgid, sizeof(vsgid), lttng_ust_rb_alignof(vsgid));
 }
 
 static
diff --git a/liblttng-ust/lttng-context-vsuid.c b/liblttng-ust/lttng-context-vsuid.c
index 86872082..ff58a741 100644
--- a/liblttng-ust/lttng-context-vsuid.c
+++ b/liblttng-ust/lttng-context-vsuid.c
@@ -83,8 +83,7 @@ void vsuid_record(struct lttng_ust_ctx_field *field,
 	uid_t vsuid;
 
 	vsuid = get_vsuid();
-	lttng_ust_lib_ring_buffer_align_ctx(ctx, lttng_ust_rb_alignof(vsuid));
-	chan->ops->event_write(ctx, &vsuid, sizeof(vsuid));
+	chan->ops->event_write(ctx, &vsuid, sizeof(vsuid), lttng_ust_rb_alignof(vsuid));
 }
 
 static
diff --git a/liblttng-ust/lttng-context-vtid.c b/liblttng-ust/lttng-context-vtid.c
index f6dd1c71..297d8025 100644
--- a/liblttng-ust/lttng-context-vtid.c
+++ b/liblttng-ust/lttng-context-vtid.c
@@ -66,8 +66,7 @@ void vtid_record(struct lttng_ust_ctx_field *field,
 {
 	pid_t vtid = wrapper_getvtid();
 
-	lttng_ust_lib_ring_buffer_align_ctx(ctx, lttng_ust_rb_alignof(vtid));
-	chan->ops->event_write(ctx, &vtid, sizeof(vtid));
+	chan->ops->event_write(ctx, &vtid, sizeof(vtid), lttng_ust_rb_alignof(vtid));
 }
 
 static
diff --git a/liblttng-ust/lttng-context-vuid.c b/liblttng-ust/lttng-context-vuid.c
index ab3e9856..0e05fc4f 100644
--- a/liblttng-ust/lttng-context-vuid.c
+++ b/liblttng-ust/lttng-context-vuid.c
@@ -79,8 +79,7 @@ void vuid_record(struct lttng_ust_ctx_field *field,
 	uid_t vuid;
 
 	vuid = get_vuid();
-	lttng_ust_lib_ring_buffer_align_ctx(ctx, lttng_ust_rb_alignof(vuid));
-	chan->ops->event_write(ctx, &vuid, sizeof(vuid));
+	chan->ops->event_write(ctx, &vuid, sizeof(vuid), lttng_ust_rb_alignof(vuid));
 }
 
 static
diff --git a/liblttng-ust/lttng-events.c b/liblttng-ust/lttng-events.c
index 140e5cae..6da3a1c9 100644
--- a/liblttng-ust/lttng-events.c
+++ b/liblttng-ust/lttng-events.c
@@ -801,7 +801,7 @@ int lttng_event_recorder_create(struct lttng_ust_event_desc *desc,
 		desc->nr_fields,
 		desc->fields,
 		uri,
-		&event_recorder->id);
+		&event_recorder->priv->id);
 	if (ret < 0) {
 		DBG("Error (%d) registering event to sessiond", ret);
 		goto sessiond_register_error;
diff --git a/liblttng-ust/lttng-ring-buffer-client.h b/liblttng-ust/lttng-ring-buffer-client.h
index 350cf0ed..01ad89da 100644
--- a/liblttng-ust/lttng-ring-buffer-client.h
+++ b/liblttng-ust/lttng-ring-buffer-client.h
@@ -18,6 +18,7 @@
 #include "context-internal.h"
 #include "lttng-tracer.h"
 #include "../libringbuffer/frontend_types.h"
+#include <urcu/tls-compat.h>
 
 #define LTTNG_COMPACT_EVENT_BITS       5
 #define LTTNG_COMPACT_TSC_BITS         27
@@ -68,6 +69,21 @@ struct lttng_client_ctx {
 	struct lttng_ust_ctx *event_ctx;
 };
 
+/*
+ * Indexed by lib_ring_buffer_nesting_count().
+ */
+typedef struct lttng_ust_lib_ring_buffer_ctx_private private_ctx_stack_t[LIB_RING_BUFFER_MAX_NESTING];
+static DEFINE_URCU_TLS(private_ctx_stack_t, private_ctx_stack);
+
+/*
+ * Force a read (imply TLS fixup for dlopen) of TLS variables.
+ */
+static
+void lttng_fixup_rb_client_tls(void)
+{
+	asm volatile ("" : : "m" (URCU_TLS(private_ctx_stack)));
+}
+
 static inline uint64_t lib_ring_buffer_clock_read(struct lttng_ust_lib_ring_buffer_channel *chan)
 {
 	return trace_clock_read64();
@@ -184,7 +200,7 @@ size_t record_header_size(const struct lttng_ust_lib_ring_buffer_config *config,
 	case 1:	/* compact */
 		padding = lttng_ust_lib_ring_buffer_align(offset, lttng_ust_rb_alignof(uint32_t));
 		offset += padding;
-		if (!(ctx->rflags & (RING_BUFFER_RFLAG_FULL_TSC | LTTNG_RFLAG_EXTENDED))) {
+		if (!(ctx->priv->rflags & (RING_BUFFER_RFLAG_FULL_TSC | LTTNG_RFLAG_EXTENDED))) {
 			offset += sizeof(uint32_t);	/* id and timestamp */
 		} else {
 			/* Minimum space taken by LTTNG_COMPACT_EVENT_BITS id */
@@ -200,7 +216,7 @@ size_t record_header_size(const struct lttng_ust_lib_ring_buffer_config *config,
 		padding = lttng_ust_lib_ring_buffer_align(offset, lttng_ust_rb_alignof(uint16_t));
 		offset += padding;
 		offset += sizeof(uint16_t);
-		if (!(ctx->rflags & (RING_BUFFER_RFLAG_FULL_TSC | LTTNG_RFLAG_EXTENDED))) {
+		if (!(ctx->priv->rflags & (RING_BUFFER_RFLAG_FULL_TSC | LTTNG_RFLAG_EXTENDED))) {
 			offset += lttng_ust_lib_ring_buffer_align(offset, lttng_ust_rb_alignof(uint32_t));
 			offset += sizeof(uint32_t);	/* timestamp */
 		} else {
@@ -247,9 +263,9 @@ void lttng_write_event_header(const struct lttng_ust_lib_ring_buffer_config *con
 			    struct lttng_client_ctx *client_ctx,
 			    uint32_t event_id)
 {
-	struct lttng_ust_channel_buffer *lttng_chan = channel_get_private(ctx->chan);
+	struct lttng_ust_channel_buffer *lttng_chan = channel_get_private(ctx->priv->chan);
 
-	if (caa_unlikely(ctx->rflags))
+	if (caa_unlikely(ctx->priv->rflags))
 		goto slow_path;
 
 	switch (lttng_chan->priv->header_type) {
@@ -264,13 +280,13 @@ void lttng_write_event_header(const struct lttng_ust_lib_ring_buffer_config *con
 		bt_bitfield_write(&id_time, uint32_t,
 				LTTNG_COMPACT_EVENT_BITS,
 				LTTNG_COMPACT_TSC_BITS,
-				ctx->tsc);
+				ctx->priv->tsc);
 		lib_ring_buffer_write(config, ctx, &id_time, sizeof(id_time));
 		break;
 	}
 	case 2:	/* large */
 	{
-		uint32_t timestamp = (uint32_t) ctx->tsc;
+		uint32_t timestamp = (uint32_t) ctx->priv->tsc;
 		uint16_t id = event_id;
 
 		lib_ring_buffer_write(config, ctx, &id, sizeof(id));
@@ -298,11 +314,12 @@ void lttng_write_event_header_slow(const struct lttng_ust_lib_ring_buffer_config
 				 struct lttng_client_ctx *client_ctx,
 				 uint32_t event_id)
 {
-	struct lttng_ust_channel_buffer *lttng_chan = channel_get_private(ctx->chan);
+	struct lttng_ust_lib_ring_buffer_ctx_private *ctx_private = ctx->priv;
+	struct lttng_ust_channel_buffer *lttng_chan = channel_get_private(ctx->priv->chan);
 
 	switch (lttng_chan->priv->header_type) {
 	case 1:	/* compact */
-		if (!(ctx->rflags & (RING_BUFFER_RFLAG_FULL_TSC | LTTNG_RFLAG_EXTENDED))) {
+		if (!(ctx_private->rflags & (RING_BUFFER_RFLAG_FULL_TSC | LTTNG_RFLAG_EXTENDED))) {
 			uint32_t id_time = 0;
 
 			bt_bitfield_write(&id_time, uint32_t,
@@ -312,11 +329,11 @@ void lttng_write_event_header_slow(const struct lttng_ust_lib_ring_buffer_config
 			bt_bitfield_write(&id_time, uint32_t,
 					LTTNG_COMPACT_EVENT_BITS,
 					LTTNG_COMPACT_TSC_BITS,
-					ctx->tsc);
+					ctx_private->tsc);
 			lib_ring_buffer_write(config, ctx, &id_time, sizeof(id_time));
 		} else {
 			uint8_t id = 0;
-			uint64_t timestamp = ctx->tsc;
+			uint64_t timestamp = ctx_private->tsc;
 
 			bt_bitfield_write(&id, uint8_t,
 					0,
@@ -332,8 +349,8 @@ void lttng_write_event_header_slow(const struct lttng_ust_lib_ring_buffer_config
 		break;
 	case 2:	/* large */
 	{
-		if (!(ctx->rflags & (RING_BUFFER_RFLAG_FULL_TSC | LTTNG_RFLAG_EXTENDED))) {
-			uint32_t timestamp = (uint32_t) ctx->tsc;
+		if (!(ctx_private->rflags & (RING_BUFFER_RFLAG_FULL_TSC | LTTNG_RFLAG_EXTENDED))) {
+			uint32_t timestamp = (uint32_t) ctx_private->tsc;
 			uint16_t id = event_id;
 
 			lib_ring_buffer_write(config, ctx, &id, sizeof(id));
@@ -341,7 +358,7 @@ void lttng_write_event_header_slow(const struct lttng_ust_lib_ring_buffer_config
 			lib_ring_buffer_write(config, ctx, &timestamp, sizeof(timestamp));
 		} else {
 			uint16_t id = 65535;
-			uint64_t timestamp = ctx->tsc;
+			uint64_t timestamp = ctx_private->tsc;
 
 			lib_ring_buffer_write(config, ctx, &id, sizeof(id));
 			/* Align extended struct on largest member */
@@ -693,16 +710,16 @@ void lttng_channel_destroy(struct lttng_ust_channel_buffer *lttng_chan_buf)
 }
 
 static
-int lttng_event_reserve(struct lttng_ust_lib_ring_buffer_ctx *ctx,
-		      uint32_t event_id)
+int lttng_event_reserve(struct lttng_ust_lib_ring_buffer_ctx *ctx)
 {
-	struct lttng_ust_stack_ctx *lttng_ctx = ctx->priv;
-	struct lttng_ust_event_recorder *event_recorder = lttng_ctx->event_recorder;
+	struct lttng_ust_event_recorder *event_recorder = ctx->client_priv;
 	struct lttng_ust_channel_buffer *lttng_chan = event_recorder->chan;
 	struct lttng_client_ctx client_ctx;
-	int ret;
+	int ret, nesting;
+	struct lttng_ust_lib_ring_buffer_ctx_private *private_ctx;
+	uint32_t event_id;
 
-	ctx->chan = lttng_chan->priv->rb_chan;
+	event_id = event_recorder->priv->id;
 	client_ctx.chan_ctx = lttng_ust_rcu_dereference(lttng_chan->priv->ctx);
 	client_ctx.event_ctx = lttng_ust_rcu_dereference(event_recorder->priv->ctx);
 	/* Compute internal size of context structures. */
@@ -711,17 +728,25 @@ int lttng_event_reserve(struct lttng_ust_lib_ring_buffer_ctx *ctx,
 	ctx_get_struct_size(client_ctx.event_ctx, &client_ctx.event_context_len,
 			APP_CTX_ENABLED);
 
-	if (lib_ring_buffer_nesting_inc(&client_config) < 0)
+	nesting = lib_ring_buffer_nesting_inc(&client_config);
+	if (nesting < 0)
 		return -EPERM;
 
+	private_ctx = &private_ctx_stack[nesting];
+	memset(private_ctx, 0, sizeof(*private_ctx));
+	private_ctx->pub = ctx;
+	private_ctx->chan = lttng_chan->priv->rb_chan;
+
+	ctx->priv = private_ctx;
+
 	switch (lttng_chan->priv->header_type) {
 	case 1:	/* compact */
 		if (event_id > 30)
-			ctx->rflags |= LTTNG_RFLAG_EXTENDED;
+			private_ctx->rflags |= LTTNG_RFLAG_EXTENDED;
 		break;
 	case 2:	/* large */
 		if (event_id > 65534)
-			ctx->rflags |= LTTNG_RFLAG_EXTENDED;
+			private_ctx->rflags |= LTTNG_RFLAG_EXTENDED;
 		break;
 	default:
 		WARN_ON_ONCE(1);
@@ -731,7 +756,7 @@ int lttng_event_reserve(struct lttng_ust_lib_ring_buffer_ctx *ctx,
 	if (caa_unlikely(ret))
 		goto put;
 	if (lib_ring_buffer_backend_get_pages(&client_config, ctx,
-			&ctx->backend_pages)) {
+			&private_ctx->backend_pages)) {
 		ret = -EPERM;
 		goto put;
 	}
@@ -750,22 +775,23 @@ void lttng_event_commit(struct lttng_ust_lib_ring_buffer_ctx *ctx)
 }
 
 static
-void lttng_event_write(struct lttng_ust_lib_ring_buffer_ctx *ctx, const void *src,
-		     size_t len)
+void lttng_event_write(struct lttng_ust_lib_ring_buffer_ctx *ctx,
+		const void *src, size_t len, size_t alignment)
 {
+	lttng_ust_lib_ring_buffer_align_ctx(ctx, alignment);
 	lib_ring_buffer_write(&client_config, ctx, src, len);
 }
 
 static
-void lttng_event_strcpy(struct lttng_ust_lib_ring_buffer_ctx *ctx, const char *src,
-		     size_t len)
+void lttng_event_strcpy(struct lttng_ust_lib_ring_buffer_ctx *ctx,
+		const char *src, size_t len)
 {
 	lib_ring_buffer_strcpy(&client_config, ctx, src, len, '#');
 }
 
 static
 void lttng_event_pstrcpy_pad(struct lttng_ust_lib_ring_buffer_ctx *ctx,
-		     const char *src, size_t len)
+		const char *src, size_t len)
 {
 	lib_ring_buffer_pstrcpy(&client_config, ctx, src, len, '\0');
 }
@@ -832,6 +858,7 @@ void RING_BUFFER_MODE_TEMPLATE_INIT(void)
 {
 	DBG("LTT : ltt ring buffer client \"%s\" init\n",
 		"relay-" RING_BUFFER_MODE_TEMPLATE_STRING "-mmap");
+	lttng_fixup_rb_client_tls();
 	lttng_transport_register(&lttng_relay_transport);
 }
 
diff --git a/liblttng-ust/lttng-ring-buffer-metadata-client.h b/liblttng-ust/lttng-ring-buffer-metadata-client.h
index 0911d37a..8a0fdc5c 100644
--- a/liblttng-ust/lttng-ring-buffer-metadata-client.h
+++ b/liblttng-ust/lttng-ring-buffer-metadata-client.h
@@ -15,6 +15,7 @@
 #include "ust-compat.h"
 #include "lttng-tracer.h"
 #include "../libringbuffer/frontend_types.h"
+#include <urcu/tls-compat.h>
 
 struct metadata_packet_header {
 	uint32_t magic;			/* 0x75D11D57 */
@@ -36,6 +37,9 @@ struct metadata_record_header {
 
 static const struct lttng_ust_lib_ring_buffer_config client_config;
 
+/* No nested use supported for metadata ring buffer. */
+static DEFINE_URCU_TLS(struct lttng_ust_lib_ring_buffer_ctx_private, private_ctx);
+
 static inline uint64_t lib_ring_buffer_clock_read(struct lttng_ust_lib_ring_buffer_channel *chan)
 {
 	return 0;
@@ -240,15 +244,19 @@ void lttng_channel_destroy(struct lttng_ust_channel_buffer *lttng_chan_buf)
 }
 
 static
-int lttng_event_reserve(struct lttng_ust_lib_ring_buffer_ctx *ctx, uint32_t event_id)
+int lttng_event_reserve(struct lttng_ust_lib_ring_buffer_ctx *ctx)
 {
 	int ret;
 
+	memset(&private_ctx, 0, sizeof(private_ctx));
+	private_ctx.pub = ctx;
+	private_ctx.chan = ctx->client_priv;
+	ctx->priv = &private_ctx;
 	ret = lib_ring_buffer_reserve(&client_config, ctx, NULL);
 	if (ret)
 		return ret;
 	if (lib_ring_buffer_backend_get_pages(&client_config, ctx,
-			&ctx->backend_pages))
+			&ctx->priv->backend_pages))
 		return -EPERM;
 	return 0;
 }
@@ -260,9 +268,10 @@ void lttng_event_commit(struct lttng_ust_lib_ring_buffer_ctx *ctx)
 }
 
 static
-void lttng_event_write(struct lttng_ust_lib_ring_buffer_ctx *ctx, const void *src,
-		     size_t len)
+void lttng_event_write(struct lttng_ust_lib_ring_buffer_ctx *ctx,
+		const void *src, size_t len, size_t alignment)
 {
+	lttng_ust_lib_ring_buffer_align_ctx(ctx, alignment);
 	lib_ring_buffer_write(&client_config, ctx, src, len);
 }
 
diff --git a/liblttng-ust/ust-core.c b/liblttng-ust/ust-core.c
index 089dd910..88d4f558 100644
--- a/liblttng-ust/ust-core.c
+++ b/liblttng-ust/ust-core.c
@@ -121,8 +121,7 @@ void lttng_ust_dummy_record(struct lttng_ust_ctx_field *field,
 {
 	char sel_char = (char) LTTNG_UST_DYNAMIC_TYPE_NONE;
 
-	lttng_ust_lib_ring_buffer_align_ctx(ctx, lttng_ust_rb_alignof(sel_char));
-	chan->ops->event_write(ctx, &sel_char, sizeof(sel_char));
+	chan->ops->event_write(ctx, &sel_char, sizeof(sel_char), lttng_ust_rb_alignof(sel_char));
 }
 
 void lttng_ust_dummy_get_value(struct lttng_ust_ctx_field *field,
diff --git a/liblttng-ust/ust-events-internal.h b/liblttng-ust/ust-events-internal.h
index af72aa66..055e4f6e 100644
--- a/liblttng-ust/ust-events-internal.h
+++ b/liblttng-ust/ust-events-internal.h
@@ -284,6 +284,7 @@ struct lttng_ust_event_recorder_private {
 	struct cds_list_head node;		/* Event recorder list */
 	struct cds_hlist_node hlist;		/* Hash table of event recorders */
 	struct lttng_ust_ctx *ctx;
+	unsigned int id;
 };
 
 struct lttng_ust_event_notifier_private {
diff --git a/libringbuffer/backend.h b/libringbuffer/backend.h
index 2fe06cef..fff4f9ec 100644
--- a/libringbuffer/backend.h
+++ b/libringbuffer/backend.h
@@ -68,9 +68,10 @@ void lib_ring_buffer_write(const struct lttng_ust_lib_ring_buffer_config *config
 			   struct lttng_ust_lib_ring_buffer_ctx *ctx,
 			   const void *src, size_t len)
 {
-	struct channel_backend *chanb = &ctx->chan->backend;
-	struct lttng_ust_shm_handle *handle = ctx->chan->handle;
-	size_t offset = ctx->buf_offset;
+	struct lttng_ust_lib_ring_buffer_ctx_private *ctx_private = ctx->priv;
+	struct channel_backend *chanb = &ctx_private->chan->backend;
+	struct lttng_ust_shm_handle *handle = ctx_private->chan->handle;
+	size_t offset = ctx_private->buf_offset;
 	struct lttng_ust_lib_ring_buffer_backend_pages *backend_pages;
 	void *p;
 
@@ -90,7 +91,7 @@ void lib_ring_buffer_write(const struct lttng_ust_lib_ring_buffer_config *config
 	if (caa_unlikely(!p))
 		return;
 	lib_ring_buffer_do_copy(config, p, src, len);
-	ctx->buf_offset += len;
+	ctx_private->buf_offset += len;
 }
 
 /*
@@ -139,10 +140,11 @@ void lib_ring_buffer_strcpy(const struct lttng_ust_lib_ring_buffer_config *confi
 			   struct lttng_ust_lib_ring_buffer_ctx *ctx,
 			   const char *src, size_t len, char pad)
 {
-	struct channel_backend *chanb = &ctx->chan->backend;
-	struct lttng_ust_shm_handle *handle = ctx->chan->handle;
+	struct lttng_ust_lib_ring_buffer_ctx_private *ctx_private = ctx->priv;
+	struct channel_backend *chanb = &ctx_private->chan->backend;
+	struct lttng_ust_shm_handle *handle = ctx_private->chan->handle;
 	size_t count;
-	size_t offset = ctx->buf_offset;
+	size_t offset = ctx_private->buf_offset;
 	struct lttng_ust_lib_ring_buffer_backend_pages *backend_pages;
 	void *p;
 
@@ -179,7 +181,7 @@ void lib_ring_buffer_strcpy(const struct lttng_ust_lib_ring_buffer_config *confi
 	if (caa_unlikely(!p))
 		return;
 	lib_ring_buffer_do_memset(p, '\0', 1);
-	ctx->buf_offset += len;
+	ctx_private->buf_offset += len;
 }
 
 /**
@@ -203,10 +205,11 @@ void lib_ring_buffer_pstrcpy(const struct lttng_ust_lib_ring_buffer_config *conf
 			   struct lttng_ust_lib_ring_buffer_ctx *ctx,
 			   const char *src, size_t len, char pad)
 {
-	struct channel_backend *chanb = &ctx->chan->backend;
-	struct lttng_ust_shm_handle *handle = ctx->chan->handle;
+	struct lttng_ust_lib_ring_buffer_ctx_private *ctx_private = ctx->priv;
+	struct channel_backend *chanb = &ctx_private->chan->backend;
+	struct lttng_ust_shm_handle *handle = ctx_private->chan->handle;
 	size_t count;
-	size_t offset = ctx->buf_offset;
+	size_t offset = ctx_private->buf_offset;
 	struct lttng_ust_lib_ring_buffer_backend_pages *backend_pages;
 	void *p;
 
@@ -237,7 +240,7 @@ void lib_ring_buffer_pstrcpy(const struct lttng_ust_lib_ring_buffer_config *conf
 			return;
 		lib_ring_buffer_do_memset(p, pad, pad_len);
 	}
-	ctx->buf_offset += len;
+	ctx_private->buf_offset += len;
 }
 
 /*
diff --git a/libringbuffer/backend_internal.h b/libringbuffer/backend_internal.h
index 68370c7e..43d83c58 100644
--- a/libringbuffer/backend_internal.h
+++ b/libringbuffer/backend_internal.h
@@ -207,11 +207,12 @@ int lib_ring_buffer_backend_get_pages(const struct lttng_ust_lib_ring_buffer_con
 			struct lttng_ust_lib_ring_buffer_ctx *ctx,
 			struct lttng_ust_lib_ring_buffer_backend_pages **backend_pages)
 {
-	struct lttng_ust_lib_ring_buffer_backend *bufb = &ctx->buf->backend;
-	struct channel_backend *chanb = &ctx->chan->backend;
-	struct lttng_ust_shm_handle *handle = ctx->chan->handle;
+	struct lttng_ust_lib_ring_buffer_ctx_private *ctx_private = ctx->priv;
+	struct lttng_ust_lib_ring_buffer_backend *bufb = &ctx_private->buf->backend;
+	struct channel_backend *chanb = &ctx_private->chan->backend;
+	struct lttng_ust_shm_handle *handle = ctx_private->chan->handle;
 	size_t sbidx;
-	size_t offset = ctx->buf_offset;
+	size_t offset = ctx_private->buf_offset;
 	struct lttng_ust_lib_ring_buffer_backend_subbuffer *wsb;
 	struct lttng_ust_lib_ring_buffer_backend_pages_shmp *rpages;
 	unsigned long sb_bindex, id;
@@ -227,7 +228,7 @@ int lib_ring_buffer_backend_get_pages(const struct lttng_ust_lib_ring_buffer_con
 	rpages = shmp_index(handle, bufb->array, sb_bindex);
 	if (caa_unlikely(!rpages))
 		return -1;
-	CHAN_WARN_ON(ctx->chan,
+	CHAN_WARN_ON(ctx_private->chan,
 		     config->mode == RING_BUFFER_OVERWRITE
 		     && subbuffer_id_is_noref(config, id));
 	_backend_pages = shmp(handle, rpages->shmp);
@@ -243,7 +244,7 @@ struct lttng_ust_lib_ring_buffer_backend_pages *
 	lib_ring_buffer_get_backend_pages_from_ctx(const struct lttng_ust_lib_ring_buffer_config *config,
 		struct lttng_ust_lib_ring_buffer_ctx *ctx)
 {
-	return ctx->backend_pages;
+	return ctx->priv->backend_pages;
 }
 
 /*
diff --git a/libringbuffer/frontend_api.h b/libringbuffer/frontend_api.h
index 4207574f..be077e51 100644
--- a/libringbuffer/frontend_api.h
+++ b/libringbuffer/frontend_api.h
@@ -22,7 +22,8 @@
  *
  * The rint buffer buffer nesting count is a safety net to ensure tracer
  * client code will never trigger an endless recursion.
- * Returns 0 on success, -EPERM on failure (nesting count too high).
+ * Returns a nesting level >= 0 on success, -EPERM on failure (nesting
+ * count too high).
  *
  * asm volatile and "memory" clobber prevent the compiler from moving
  * instructions out of the ring buffer nesting count. This is required to ensure
@@ -37,12 +38,18 @@ int lib_ring_buffer_nesting_inc(const struct lttng_ust_lib_ring_buffer_config *c
 
 	nesting = ++URCU_TLS(lib_ring_buffer_nesting);
 	cmm_barrier();
-	if (caa_unlikely(nesting > 4)) {
+	if (caa_unlikely(nesting >= LIB_RING_BUFFER_MAX_NESTING)) {
 		WARN_ON_ONCE(1);
 		URCU_TLS(lib_ring_buffer_nesting)--;
 		return -EPERM;
 	}
-	return 0;
+	return nesting - 1;
+}
+
+static inline
+int lib_ring_buffer_nesting_count(const struct lttng_ust_lib_ring_buffer_config *config)
+{
+	return URCU_TLS(lib_ring_buffer_nesting);
 }
 
 static inline
@@ -65,13 +72,14 @@ int lib_ring_buffer_try_reserve(const struct lttng_ust_lib_ring_buffer_config *c
 				unsigned long *o_begin, unsigned long *o_end,
 				unsigned long *o_old, size_t *before_hdr_pad)
 {
-	struct lttng_ust_lib_ring_buffer_channel *chan = ctx->chan;
-	struct lttng_ust_lib_ring_buffer *buf = ctx->buf;
+	struct lttng_ust_lib_ring_buffer_ctx_private *ctx_private = ctx->priv;
+	struct lttng_ust_lib_ring_buffer_channel *chan = ctx_private->chan;
+	struct lttng_ust_lib_ring_buffer *buf = ctx_private->buf;
 	*o_begin = v_read(config, &buf->offset);
 	*o_old = *o_begin;
 
-	ctx->tsc = lib_ring_buffer_clock_read(chan);
-	if ((int64_t) ctx->tsc == -EIO)
+	ctx_private->tsc = lib_ring_buffer_clock_read(chan);
+	if ((int64_t) ctx_private->tsc == -EIO)
 		return 1;
 
 	/*
@@ -81,18 +89,18 @@ int lib_ring_buffer_try_reserve(const struct lttng_ust_lib_ring_buffer_config *c
 	 */
 	//prefetch(&buf->commit_hot[subbuf_index(*o_begin, chan)]);
 
-	if (last_tsc_overflow(config, buf, ctx->tsc))
-		ctx->rflags |= RING_BUFFER_RFLAG_FULL_TSC;
+	if (last_tsc_overflow(config, buf, ctx_private->tsc))
+		ctx_private->rflags |= RING_BUFFER_RFLAG_FULL_TSC;
 
 	if (caa_unlikely(subbuf_offset(*o_begin, chan) == 0))
 		return 1;
 
-	ctx->slot_size = record_header_size(config, chan, *o_begin,
+	ctx_private->slot_size = record_header_size(config, chan, *o_begin,
 					    before_hdr_pad, ctx, client_ctx);
-	ctx->slot_size +=
-		lttng_ust_lib_ring_buffer_align(*o_begin + ctx->slot_size,
+	ctx_private->slot_size +=
+		lttng_ust_lib_ring_buffer_align(*o_begin + ctx_private->slot_size,
 				      ctx->largest_align) + ctx->data_size;
-	if (caa_unlikely((subbuf_offset(*o_begin, chan) + ctx->slot_size)
+	if (caa_unlikely((subbuf_offset(*o_begin, chan) + ctx_private->slot_size)
 		     > chan->backend.subbuf_size))
 		return 1;
 
@@ -100,7 +108,7 @@ int lib_ring_buffer_try_reserve(const struct lttng_ust_lib_ring_buffer_config *c
 	 * Record fits in the current buffer and we are not on a switch
 	 * boundary. It's safe to write.
 	 */
-	*o_end = *o_begin + ctx->slot_size;
+	*o_end = *o_begin + ctx_private->slot_size;
 
 	if (caa_unlikely((subbuf_offset(*o_end, chan)) == 0))
 		/*
@@ -133,8 +141,9 @@ int lib_ring_buffer_reserve(const struct lttng_ust_lib_ring_buffer_config *confi
 			    struct lttng_ust_lib_ring_buffer_ctx *ctx,
 			    void *client_ctx)
 {
-	struct lttng_ust_lib_ring_buffer_channel *chan = ctx->chan;
-	struct lttng_ust_shm_handle *handle = ctx->chan->handle;
+	struct lttng_ust_lib_ring_buffer_ctx_private *ctx_private = ctx->priv;
+	struct lttng_ust_lib_ring_buffer_channel *chan = ctx_private->chan;
+	struct lttng_ust_shm_handle *handle = chan->handle;
 	struct lttng_ust_lib_ring_buffer *buf;
 	unsigned long o_begin, o_end, o_old;
 	size_t before_hdr_pad = 0;
@@ -143,8 +152,8 @@ int lib_ring_buffer_reserve(const struct lttng_ust_lib_ring_buffer_config *confi
 		return -EAGAIN;
 
 	if (config->alloc == RING_BUFFER_ALLOC_PER_CPU) {
-		ctx->reserve_cpu = lttng_ust_get_cpu();
-		buf = shmp(handle, chan->backend.buf[ctx->reserve_cpu].shmp);
+		ctx_private->reserve_cpu = lttng_ust_get_cpu();
+		buf = shmp(handle, chan->backend.buf[ctx_private->reserve_cpu].shmp);
 	} else {
 		buf = shmp(handle, chan->backend.buf[0].shmp);
 	}
@@ -152,7 +161,7 @@ int lib_ring_buffer_reserve(const struct lttng_ust_lib_ring_buffer_config *confi
 		return -EIO;
 	if (caa_unlikely(uatomic_read(&buf->record_disabled)))
 		return -EAGAIN;
-	ctx->buf = buf;
+	ctx_private->buf = buf;
 
 	/*
 	 * Perform retryable operations.
@@ -161,7 +170,7 @@ int lib_ring_buffer_reserve(const struct lttng_ust_lib_ring_buffer_config *confi
 						 &o_end, &o_old, &before_hdr_pad)))
 		goto slow_path;
 
-	if (caa_unlikely(v_cmpxchg(config, &ctx->buf->offset, o_old, o_end)
+	if (caa_unlikely(v_cmpxchg(config, &buf->offset, o_old, o_end)
 		     != o_old))
 		goto slow_path;
 
@@ -171,21 +180,21 @@ int lib_ring_buffer_reserve(const struct lttng_ust_lib_ring_buffer_config *confi
 	 * record headers, never the opposite (missing a full TSC record header
 	 * when it would be needed).
 	 */
-	save_last_tsc(config, ctx->buf, ctx->tsc);
+	save_last_tsc(config, buf, ctx_private->tsc);
 
 	/*
 	 * Push the reader if necessary
 	 */
-	lib_ring_buffer_reserve_push_reader(ctx->buf, chan, o_end - 1);
+	lib_ring_buffer_reserve_push_reader(buf, chan, o_end - 1);
 
 	/*
 	 * Clear noref flag for this subbuffer.
 	 */
-	lib_ring_buffer_clear_noref(config, &ctx->buf->backend,
+	lib_ring_buffer_clear_noref(config, &buf->backend,
 				subbuf_index(o_end - 1, chan), handle);
 
-	ctx->pre_offset = o_begin;
-	ctx->buf_offset = o_begin + before_hdr_pad;
+	ctx_private->pre_offset = o_begin;
+	ctx_private->buf_offset = o_begin + before_hdr_pad;
 	return 0;
 slow_path:
 	return lib_ring_buffer_reserve_slow(ctx, client_ctx);
@@ -227,10 +236,11 @@ static inline
 void lib_ring_buffer_commit(const struct lttng_ust_lib_ring_buffer_config *config,
 			    const struct lttng_ust_lib_ring_buffer_ctx *ctx)
 {
-	struct lttng_ust_lib_ring_buffer_channel *chan = ctx->chan;
-	struct lttng_ust_shm_handle *handle = ctx->chan->handle;
-	struct lttng_ust_lib_ring_buffer *buf = ctx->buf;
-	unsigned long offset_end = ctx->buf_offset;
+	struct lttng_ust_lib_ring_buffer_ctx_private *ctx_private = ctx->priv;
+	struct lttng_ust_lib_ring_buffer_channel *chan = ctx_private->chan;
+	struct lttng_ust_shm_handle *handle = chan->handle;
+	struct lttng_ust_lib_ring_buffer *buf = ctx_private->buf;
+	unsigned long offset_end = ctx_private->buf_offset;
 	unsigned long endidx = subbuf_index(offset_end - 1, chan);
 	unsigned long commit_count;
 	struct commit_counters_hot *cc_hot = shmp_index(handle,
@@ -250,7 +260,7 @@ void lib_ring_buffer_commit(const struct lttng_ust_lib_ring_buffer_config *confi
 	 */
 	cmm_smp_wmb();
 
-	v_add(config, ctx->slot_size, &cc_hot->cc);
+	v_add(config, ctx_private->slot_size, &cc_hot->cc);
 
 	/*
 	 * commit count read can race with concurrent OOO commit count updates.
@@ -273,7 +283,7 @@ void lib_ring_buffer_commit(const struct lttng_ust_lib_ring_buffer_config *confi
 	commit_count = v_read(config, &cc_hot->cc);
 
 	lib_ring_buffer_check_deliver(config, buf, chan, offset_end - 1,
-				      commit_count, endidx, handle, ctx->tsc);
+				      commit_count, endidx, handle, ctx_private->tsc);
 	/*
 	 * Update used size at each commit. It's needed only for extracting
 	 * ring_buffer buffers from vmcore, after crash.
@@ -296,8 +306,9 @@ static inline
 int lib_ring_buffer_try_discard_reserve(const struct lttng_ust_lib_ring_buffer_config *config,
 					const struct lttng_ust_lib_ring_buffer_ctx *ctx)
 {
-	struct lttng_ust_lib_ring_buffer *buf = ctx->buf;
-	unsigned long end_offset = ctx->pre_offset + ctx->slot_size;
+	struct lttng_ust_lib_ring_buffer_ctx_private *ctx_private = ctx->priv;
+	struct lttng_ust_lib_ring_buffer *buf = ctx_private->buf;
+	unsigned long end_offset = ctx_private->pre_offset + ctx_private->slot_size;
 
 	/*
 	 * We need to ensure that if the cmpxchg succeeds and discards the
@@ -313,7 +324,7 @@ int lib_ring_buffer_try_discard_reserve(const struct lttng_ust_lib_ring_buffer_c
 	 */
 	save_last_tsc(config, buf, 0ULL);
 
-	if (caa_likely(v_cmpxchg(config, &buf->offset, end_offset, ctx->pre_offset)
+	if (caa_likely(v_cmpxchg(config, &buf->offset, end_offset, ctx_private->pre_offset)
 		   != end_offset))
 		return -EPERM;
 	else
diff --git a/libringbuffer/frontend_types.h b/libringbuffer/frontend_types.h
index 83564768..106c1e12 100644
--- a/libringbuffer/frontend_types.h
+++ b/libringbuffer/frontend_types.h
@@ -26,6 +26,8 @@
 #include "shm_types.h"
 #include "vatomic.h"
 
+#define LIB_RING_BUFFER_MAX_NESTING	5
+
 /*
  * A switch is done during tracing or as a final flush after tracing (so it
  * won't write in the new sub-buffer).
@@ -223,6 +225,43 @@ struct lttng_ust_lib_ring_buffer {
 	char padding[RB_RING_BUFFER_PADDING];
 } __attribute__((aligned(CAA_CACHE_LINE_SIZE)));
 
+/*
+ * ring buffer private context
+ *
+ * Private context passed to lib_ring_buffer_reserve(), lib_ring_buffer_commit(),
+ * lib_ring_buffer_try_discard_reserve(), lttng_ust_lib_ring_buffer_align_ctx() and
+ * lib_ring_buffer_write().
+ *
+ * This context is allocated on an internal shadow-stack by a successful reserve
+ * operation, used by align/write, and freed by commit.
+ */
+
+struct lttng_ust_lib_ring_buffer_ctx_private {
+	/* input received by lib_ring_buffer_reserve(). */
+	struct lttng_ust_lib_ring_buffer_ctx *pub;
+	struct lttng_ust_lib_ring_buffer_channel *chan; /* channel */
+
+	/* output from lib_ring_buffer_reserve() */
+	int reserve_cpu;			/* processor id updated by the reserve */
+	size_t slot_size;			/* size of the reserved slot */
+	unsigned long buf_offset;		/* offset following the record header */
+	unsigned long pre_offset;		/*
+						 * Initial offset position _before_
+						 * the record is written. Positioned
+						 * prior to record header alignment
+						 * padding.
+						 */
+	uint64_t tsc;				/* time-stamp counter value */
+	unsigned int rflags;			/* reservation flags */
+	void *ip;				/* caller ip address */
+
+	struct lttng_ust_lib_ring_buffer *buf;	/*
+						 * buffer corresponding to processor id
+						 * for this channel
+						 */
+	struct lttng_ust_lib_ring_buffer_backend_pages *backend_pages;
+};
+
 static inline
 void *channel_get_private_config(struct lttng_ust_lib_ring_buffer_channel *chan)
 {
@@ -270,4 +309,21 @@ void channel_set_private(struct lttng_ust_lib_ring_buffer_channel *chan, void *p
 		_____ret = _____ret; /* For clang "unused result". */	\
 	})
 
+/**
+ * lttng_ust_lib_ring_buffer_align_ctx - Align context offset on "alignment"
+ * @ctx: ring buffer context.
+ */
+static inline lttng_ust_notrace
+void lttng_ust_lib_ring_buffer_align_ctx(struct lttng_ust_lib_ring_buffer_ctx *ctx,
+			   size_t alignment);
+static inline
+void lttng_ust_lib_ring_buffer_align_ctx(struct lttng_ust_lib_ring_buffer_ctx *ctx,
+			   size_t alignment)
+{
+	struct lttng_ust_lib_ring_buffer_ctx_private *ctx_private = ctx->priv;
+
+	ctx_private->buf_offset += lttng_ust_lib_ring_buffer_align(ctx_private->buf_offset,
+						 alignment);
+}
+
 #endif /* _LTTNG_RING_BUFFER_FRONTEND_TYPES_H */
diff --git a/libringbuffer/ring_buffer_frontend.c b/libringbuffer/ring_buffer_frontend.c
index 8dfecf1d..8112ced4 100644
--- a/libringbuffer/ring_buffer_frontend.c
+++ b/libringbuffer/ring_buffer_frontend.c
@@ -2124,8 +2124,9 @@ int lib_ring_buffer_try_reserve_slow(struct lttng_ust_lib_ring_buffer *buf,
 				     struct lttng_ust_lib_ring_buffer_ctx *ctx,
 				     void *client_ctx)
 {
+	struct lttng_ust_lib_ring_buffer_ctx_private *ctx_private = ctx->priv;
 	const struct lttng_ust_lib_ring_buffer_config *config = &chan->backend.config;
-	struct lttng_ust_shm_handle *handle = ctx->chan->handle;
+	struct lttng_ust_shm_handle *handle = chan->handle;
 	unsigned long reserve_commit_diff, offset_cmp;
 	int timeout_left_ms = lttng_ust_ringbuffer_get_timeout(chan);
 
@@ -2137,14 +2138,14 @@ retry:
 	offsets->switch_old_end = 0;
 	offsets->pre_header_padding = 0;
 
-	ctx->tsc = config->cb.ring_buffer_clock_read(chan);
-	if ((int64_t) ctx->tsc == -EIO)
+	ctx_private->tsc = config->cb.ring_buffer_clock_read(chan);
+	if ((int64_t) ctx_private->tsc == -EIO)
 		return -EIO;
 
-	if (last_tsc_overflow(config, buf, ctx->tsc))
-		ctx->rflags |= RING_BUFFER_RFLAG_FULL_TSC;
+	if (last_tsc_overflow(config, buf, ctx_private->tsc))
+		ctx_private->rflags |= RING_BUFFER_RFLAG_FULL_TSC;
 
-	if (caa_unlikely(subbuf_offset(offsets->begin, ctx->chan) == 0)) {
+	if (caa_unlikely(subbuf_offset(offsets->begin, chan) == 0)) {
 		offsets->switch_new_start = 1;		/* For offsets->begin */
 	} else {
 		offsets->size = config->cb.record_header_size(config, chan,
@@ -2153,7 +2154,7 @@ retry:
 						ctx, client_ctx);
 		offsets->size +=
 			lttng_ust_lib_ring_buffer_align(offsets->begin + offsets->size,
-					      ctx->largest_align)
+					     ctx->largest_align)
 			+ ctx->data_size;
 		if (caa_unlikely(subbuf_offset(offsets->begin, chan) +
 			     offsets->size > chan->backend.subbuf_size)) {
@@ -2313,20 +2314,21 @@ retry:
 int lib_ring_buffer_reserve_slow(struct lttng_ust_lib_ring_buffer_ctx *ctx,
 		void *client_ctx)
 {
-	struct lttng_ust_lib_ring_buffer_channel *chan = ctx->chan;
-	struct lttng_ust_shm_handle *handle = ctx->chan->handle;
+	struct lttng_ust_lib_ring_buffer_ctx_private *ctx_private = ctx->priv;
+	struct lttng_ust_lib_ring_buffer_channel *chan = ctx_private->chan;
+	struct lttng_ust_shm_handle *handle = chan->handle;
 	const struct lttng_ust_lib_ring_buffer_config *config = &chan->backend.config;
 	struct lttng_ust_lib_ring_buffer *buf;
 	struct switch_offsets offsets;
 	int ret;
 
 	if (config->alloc == RING_BUFFER_ALLOC_PER_CPU)
-		buf = shmp(handle, chan->backend.buf[ctx->reserve_cpu].shmp);
+		buf = shmp(handle, chan->backend.buf[ctx_private->reserve_cpu].shmp);
 	else
 		buf = shmp(handle, chan->backend.buf[0].shmp);
 	if (!buf)
 		return -EIO;
-	ctx->buf = buf;
+	ctx_private->buf = buf;
 
 	offsets.size = 0;
 
@@ -2345,7 +2347,7 @@ int lib_ring_buffer_reserve_slow(struct lttng_ust_lib_ring_buffer_ctx *ctx,
 	 * records, never the opposite (missing a full TSC record when it would
 	 * be needed).
 	 */
-	save_last_tsc(config, buf, ctx->tsc);
+	save_last_tsc(config, buf, ctx_private->tsc);
 
 	/*
 	 * Push the reader if necessary
@@ -2366,21 +2368,21 @@ int lib_ring_buffer_reserve_slow(struct lttng_ust_lib_ring_buffer_ctx *ctx,
 		lib_ring_buffer_clear_noref(config, &buf->backend,
 					    subbuf_index(offsets.old - 1, chan),
 					    handle);
-		lib_ring_buffer_switch_old_end(buf, chan, &offsets, ctx->tsc, handle);
+		lib_ring_buffer_switch_old_end(buf, chan, &offsets, ctx_private->tsc, handle);
 	}
 
 	/*
 	 * Populate new subbuffer.
 	 */
 	if (caa_unlikely(offsets.switch_new_start))
-		lib_ring_buffer_switch_new_start(buf, chan, &offsets, ctx->tsc, handle);
+		lib_ring_buffer_switch_new_start(buf, chan, &offsets, ctx_private->tsc, handle);
 
 	if (caa_unlikely(offsets.switch_new_end))
-		lib_ring_buffer_switch_new_end(buf, chan, &offsets, ctx->tsc, handle);
+		lib_ring_buffer_switch_new_end(buf, chan, &offsets, ctx_private->tsc, handle);
 
-	ctx->slot_size = offsets.size;
-	ctx->pre_offset = offsets.begin;
-	ctx->buf_offset = offsets.begin + offsets.pre_header_padding;
+	ctx_private->slot_size = offsets.size;
+	ctx_private->pre_offset = offsets.begin;
+	ctx_private->buf_offset = offsets.begin + offsets.pre_header_padding;
 	return 0;
 }
 
diff --git a/libringbuffer/ringbuffer-config.h b/libringbuffer/ringbuffer-config.h
index f0871811..a0eddc8b 100644
--- a/libringbuffer/ringbuffer-config.h
+++ b/libringbuffer/ringbuffer-config.h
@@ -23,7 +23,7 @@
 struct lttng_ust_lib_ring_buffer;
 struct lttng_ust_lib_ring_buffer_channel;
 struct lttng_ust_lib_ring_buffer_config;
-struct lttng_ust_lib_ring_buffer_ctx;
+struct lttng_ust_lib_ring_buffer_ctx_private;
 struct lttng_ust_shm_handle;
 
 /*
diff --git a/tests/compile/test-app-ctx/hello.c b/tests/compile/test-app-ctx/hello.c
index d1cbca4c..6e16b12f 100644
--- a/tests/compile/test-app-ctx/hello.c
+++ b/tests/compile/test-app-ctx/hello.c
@@ -109,8 +109,7 @@ void test_record(struct lttng_ust_ctx_field *field,
 	int sel = test_count % _NR_LTTNG_UST_DYNAMIC_TYPES;
 	char sel_char = (char) sel;
 
-	lttng_ust_lib_ring_buffer_align_ctx(ctx, lttng_ust_rb_alignof(char));
-	lttng_chan_buf->ops->event_write(ctx, &sel_char, sizeof(sel_char));
+	lttng_chan_buf->ops->event_write(ctx, &sel_char, sizeof(sel_char), lttng_ust_rb_alignof(char));
 	switch (sel) {
 	case LTTNG_UST_DYNAMIC_TYPE_NONE:
 		break;
@@ -118,86 +117,76 @@ void test_record(struct lttng_ust_ctx_field *field,
 	{
 		int8_t v = -8;
 
-		lttng_ust_lib_ring_buffer_align_ctx(ctx, lttng_ust_rb_alignof(v));
-		lttng_chan_buf->ops->event_write(ctx, &v, sizeof(v));
+		lttng_chan_buf->ops->event_write(ctx, &v, sizeof(v), lttng_ust_rb_alignof(v));
 		break;
 	}
 	case LTTNG_UST_DYNAMIC_TYPE_S16:
 	{
 		int16_t v = -16;
 
-		lttng_ust_lib_ring_buffer_align_ctx(ctx, lttng_ust_rb_alignof(v));
-		lttng_chan_buf->ops->event_write(ctx, &v, sizeof(v));
+		lttng_chan_buf->ops->event_write(ctx, &v, sizeof(v), lttng_ust_rb_alignof(v));
 		break;
 	}
 	case LTTNG_UST_DYNAMIC_TYPE_S32:
 	{
 		int32_t v = -32;
 
-		lttng_ust_lib_ring_buffer_align_ctx(ctx, lttng_ust_rb_alignof(v));
-		lttng_chan_buf->ops->event_write(ctx, &v, sizeof(v));
+		lttng_chan_buf->ops->event_write(ctx, &v, sizeof(v), lttng_ust_rb_alignof(v));
 		break;
 	}
 	case LTTNG_UST_DYNAMIC_TYPE_S64:
 	{
 		int64_t v = -64;
 
-		lttng_ust_lib_ring_buffer_align_ctx(ctx, lttng_ust_rb_alignof(v));
-		lttng_chan_buf->ops->event_write(ctx, &v, sizeof(v));
+		lttng_chan_buf->ops->event_write(ctx, &v, sizeof(v), lttng_ust_rb_alignof(v));
 		break;
 	}
 	case LTTNG_UST_DYNAMIC_TYPE_U8:
 	{
 		uint8_t v = 8;
 
-		lttng_ust_lib_ring_buffer_align_ctx(ctx, lttng_ust_rb_alignof(v));
-		lttng_chan_buf->ops->event_write(ctx, &v, sizeof(v));
+		lttng_chan_buf->ops->event_write(ctx, &v, sizeof(v), lttng_ust_rb_alignof(v));
 		break;
 	}
 	case LTTNG_UST_DYNAMIC_TYPE_U16:
 	{
 		uint16_t v = 16;
 
-		lttng_ust_lib_ring_buffer_align_ctx(ctx, lttng_ust_rb_alignof(v));
-		lttng_chan_buf->ops->event_write(ctx, &v, sizeof(v));
+		lttng_chan_buf->ops->event_write(ctx, &v, sizeof(v), lttng_ust_rb_alignof(v));
 		break;
 	}
 	case LTTNG_UST_DYNAMIC_TYPE_U32:
 	{
 		uint32_t v = 32;
 
-		lttng_ust_lib_ring_buffer_align_ctx(ctx, lttng_ust_rb_alignof(v));
-		lttng_chan_buf->ops->event_write(ctx, &v, sizeof(v));
+		lttng_chan_buf->ops->event_write(ctx, &v, sizeof(v), lttng_ust_rb_alignof(v));
 		break;
 	}
 	case LTTNG_UST_DYNAMIC_TYPE_U64:
 	{
 		uint64_t v = 64;
 
-		lttng_ust_lib_ring_buffer_align_ctx(ctx, lttng_ust_rb_alignof(v));
-		lttng_chan_buf->ops->event_write(ctx, &v, sizeof(v));
+		lttng_chan_buf->ops->event_write(ctx, &v, sizeof(v), lttng_ust_rb_alignof(v));
 		break;
 	}
 	case LTTNG_UST_DYNAMIC_TYPE_FLOAT:
 	{
 		float f = 22322.0;
 
-		lttng_ust_lib_ring_buffer_align_ctx(ctx, lttng_ust_rb_alignof(f));
-		lttng_chan_buf->ops->event_write(ctx, &f, sizeof(f));
+		lttng_chan_buf->ops->event_write(ctx, &f, sizeof(f), lttng_ust_rb_alignof(f));
 		break;
 	}
 	case LTTNG_UST_DYNAMIC_TYPE_DOUBLE:
 	{
 		double d = 2.0;
 
-		lttng_ust_lib_ring_buffer_align_ctx(ctx, lttng_ust_rb_alignof(d));
-		lttng_chan_buf->ops->event_write(ctx, &d, sizeof(d));
+		lttng_chan_buf->ops->event_write(ctx, &d, sizeof(d), lttng_ust_rb_alignof(d));
 		break;
 	}
 	case LTTNG_UST_DYNAMIC_TYPE_STRING:
 	{
 		const char *str = "teststr";
-		lttng_chan_buf->ops->event_write(ctx, str, strlen(str) + 1);
+		lttng_chan_buf->ops->event_write(ctx, str, strlen(str) + 1, 1);
 		break;
 	}
 	default: