/*
- * (C) Copyright 2009-2011 -
- * Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
+ * SPDX-License-Identifier: LGPL-2.1-only
*
- * LTTng UST vtid context.
+ * Copyright (C) 2009-2012 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
*
- * Dual LGPL v2.1/GPL v2 license.
+ * LTTng UST vtid context.
*/
+#define _LGPL_SOURCE
+#include <limits.h>
+#include <stddef.h>
#include <sys/types.h>
#include <unistd.h>
#include <lttng/ust-events.h>
#include <lttng/ust-tracer.h>
-#include <lttng/ringbuffer-config.h>
+#include <lttng/ringbuffer-context.h>
+#include <ust-tid.h>
+#include <urcu/tls-compat.h>
-#ifdef __linux__
-#include <syscall.h>
-#endif
-
-#if defined(_syscall0)
-_syscall0(pid_t, gettid)
-#elif defined(__NR_gettid)
-static inline pid_t gettid(void)
-{
- return syscall(__NR_gettid);
-}
-#else
-#warning "use pid as tid"
-static inline pid_t gettid(void)
-{
- return getpid();
-}
-#endif
+#include "context-internal.h"
+#include "lttng-tracer-core.h"
/*
* We cache the result to ensure we don't trigger a system call for
* each event.
*/
-static __thread pid_t cached_vtid;
+static DEFINE_URCU_TLS(pid_t, cached_vtid);
/*
* Upon fork or clone, the TID assigned to our thread is not the same as
*/
void lttng_context_vtid_reset(void)
{
- cached_vtid = 0;
+ CMM_STORE_SHARED(URCU_TLS(cached_vtid), 0);
}
static
-size_t vtid_get_size(size_t offset)
+size_t vtid_get_size(void *priv __attribute__((unused)),
+ size_t offset)
{
size_t size = 0;
- size += lib_ring_buffer_align(offset, lttng_alignof(pid_t));
+ size += lttng_ust_lib_ring_buffer_align(offset, lttng_ust_rb_alignof(pid_t));
size += sizeof(pid_t);
return size;
}
+static inline
+pid_t wrapper_getvtid(void)
+{
+ pid_t vtid;
+
+ vtid = CMM_LOAD_SHARED(URCU_TLS(cached_vtid));
+ if (caa_unlikely(!vtid)) {
+ vtid = lttng_gettid();
+ CMM_STORE_SHARED(URCU_TLS(cached_vtid), vtid);
+ }
+ return vtid;
+}
+
static
-void vtid_record(struct lttng_ctx_field *field,
+void vtid_record(void *priv __attribute__((unused)),
struct lttng_ust_lib_ring_buffer_ctx *ctx,
- struct ltt_channel *chan)
+ struct lttng_ust_channel_buffer *chan)
{
- if (caa_unlikely(!cached_vtid))
- cached_vtid = gettid();
- lib_ring_buffer_align_ctx(ctx, lttng_alignof(cached_vtid));
- chan->ops->event_write(ctx, &cached_vtid, sizeof(cached_vtid));
+ pid_t vtid = wrapper_getvtid();
+
+ chan->ops->event_write(ctx, &vtid, sizeof(vtid), lttng_ust_rb_alignof(vtid));
}
-int lttng_add_vtid_to_ctx(struct lttng_ctx **ctx)
+static
+void vtid_get_value(void *priv __attribute__((unused)),
+ struct lttng_ust_ctx_value *value)
+{
+ value->u.s64 = wrapper_getvtid();
+}
+
+static const struct lttng_ust_ctx_field *ctx_field = lttng_ust_static_ctx_field(
+ lttng_ust_static_event_field("vtid",
+ lttng_ust_static_type_integer(sizeof(pid_t) * CHAR_BIT,
+ lttng_ust_rb_alignof(pid_t) * CHAR_BIT,
+ lttng_ust_is_signed_type(pid_t),
+ BYTE_ORDER, 10),
+ false, false),
+ vtid_get_size,
+ vtid_record,
+ vtid_get_value,
+ NULL, NULL);
+
+int lttng_add_vtid_to_ctx(struct lttng_ust_ctx **ctx)
{
- struct lttng_ctx_field *field;
-
- field = lttng_append_context(ctx);
- if (!field)
- return -ENOMEM;
- if (lttng_find_context(*ctx, "vtid")) {
- lttng_remove_context_field(ctx, field);
- return -EEXIST;
+ int ret;
+
+ if (lttng_find_context(*ctx, ctx_field->event_field->name)) {
+ ret = -EEXIST;
+ goto error_find_context;
}
- field->event_field.name = "vtid";
- field->event_field.type.atype = atype_integer;
- field->event_field.type.u.basic.integer.size = sizeof(pid_t) * CHAR_BIT;
- field->event_field.type.u.basic.integer.alignment = lttng_alignof(pid_t) * CHAR_BIT;
- field->event_field.type.u.basic.integer.signedness = lttng_is_signed_type(pid_t);
- field->event_field.type.u.basic.integer.reverse_byte_order = 0;
- field->event_field.type.u.basic.integer.base = 10;
- field->event_field.type.u.basic.integer.encoding = lttng_encode_none;
- field->get_size = vtid_get_size;
- field->record = vtid_record;
+ ret = lttng_ust_context_append(ctx, ctx_field);
+ if (ret)
+ return ret;
return 0;
+
+error_find_context:
+ return ret;
+}
+
+/*
+ * Force a read (imply TLS fixup for dlopen) of TLS variables.
+ */
+void lttng_fixup_vtid_tls(void)
+{
+ asm volatile ("" : : "m" (URCU_TLS(cached_vtid)));
}