X-Git-Url: http://git.liburcu.org/?a=blobdiff_plain;f=liblttng-ust%2Flttng-context.c;h=7043c1571d78b00fe555bc38756fd54f992e4aa7;hb=6ba6fd60507f8e045bdc4f1be14e9d99c6a15f7f;hp=16894ec1032b722407ce578d43f47051a62bbc60;hpb=7dd08bec735b428479201f9f84d59c78deabdf57;p=lttng-ust.git

diff --git a/liblttng-ust/lttng-context.c b/liblttng-ust/lttng-context.c
index 16894ec1..7043c157 100644
--- a/liblttng-ust/lttng-context.c
+++ b/liblttng-ust/lttng-context.c
@@ -1,41 +1,86 @@
 /*
- * lttng-context.c
- *
- * LTTng UST trace/channel/event context management.
+ * SPDX-License-Identifier: LGPL-2.1-only
  *
  * Copyright (C) 2011 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
  *
- * This library is free software; you can redistribute it and/or
- * modify it under the terms of the GNU Lesser General Public
- * License as published by the Free Software Foundation; only
- * version 2.1 of the License.
- *
- * This library is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
- * Lesser General Public License for more details.
- *
- * You should have received a copy of the GNU Lesser General Public
- * License along with this library; if not, write to the Free Software
- * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ * LTTng UST trace/channel/event context management.
  */
 
-
+#define _LGPL_SOURCE
 #include <lttng/ust-events.h>
 #include <lttng/ust-tracer.h>
-#include <helper.h>
+#include <ust-context-provider.h>
+#include <lttng/urcu/pointer.h>
+#include <lttng/urcu/urcu-ust.h>
+#include <usterr-signal-safe.h>
+#include <ust-helper.h>
+#include <stddef.h>
 #include <string.h>
 #include <assert.h>
+#include <limits.h>
+#include "tracepoint-internal.h"
+
+#include "context-internal.h"
+
+/*
+ * The filter implementation requires that two consecutive "get" for the
+ * same context performed by the same thread return the same result.
+ */
+
+int lttng_find_context(struct lttng_ust_ctx *ctx, const char *name)
+{
+	unsigned int i;
+	const char *subname;
+
+	if (!ctx)
+		return 0;
+	if (strncmp(name, "$ctx.", strlen("$ctx.")) == 0) {
+		subname = name + strlen("$ctx.");
+	} else {
+		subname = name;
+	}
+	for (i = 0; i < ctx->nr_fields; i++) {
+		/* Skip allocated (but non-initialized) contexts */
+		if (!ctx->fields[i].event_field->name)
+			continue;
+		if (!strcmp(ctx->fields[i].event_field->name, subname))
+			return 1;
+	}
+	return 0;
+}
+
+int lttng_get_context_index(struct lttng_ust_ctx *ctx, const char *name)
+{
+	unsigned int i;
+	const char *subname;
 
-int lttng_find_context(struct lttng_ctx *ctx, const char *name)
+	if (!ctx)
+		return -1;
+	if (strncmp(name, "$ctx.", strlen("$ctx.")) == 0) {
+		subname = name + strlen("$ctx.");
+	} else {
+		subname = name;
+	}
+	for (i = 0; i < ctx->nr_fields; i++) {
+		/* Skip allocated (but non-initialized) contexts */
+		if (!ctx->fields[i].event_field->name)
+			continue;
+		if (!strcmp(ctx->fields[i].event_field->name, subname))
+			return i;
+	}
+	return -1;
+}
+
+static int lttng_find_context_provider(struct lttng_ust_ctx *ctx, const char *name)
 {
 	unsigned int i;
 
 	for (i = 0; i < ctx->nr_fields; i++) {
 		/* Skip allocated (but non-initialized) contexts */
-		if (!ctx->fields[i].event_field.name)
+		if (!ctx->fields[i].event_field->name)
 			continue;
-		if (!strcmp(ctx->fields[i].event_field.name, name))
+		if (!strncmp(ctx->fields[i].event_field->name, name,
+				strlen(name)))
 			return 1;
 	}
 	return 0;
@@ -43,50 +88,145 @@ int lttng_find_context(struct lttng_ctx *ctx, const char *name)
 
 /*
  * Note: as we append context information, the pointer location may change.
+ * lttng_ust_context_add_field leaves the new last context initialized to NULL.
  */
-struct lttng_ctx_field *lttng_append_context(struct lttng_ctx **ctx_p)
+static
+int lttng_ust_context_add_field(struct lttng_ust_ctx **ctx_p)
 {
-	struct lttng_ctx_field *field;
-	struct lttng_ctx *ctx;
+	struct lttng_ust_ctx *ctx;
 
 	if (!*ctx_p) {
-		*ctx_p = zmalloc(sizeof(struct lttng_ctx));
+		*ctx_p = zmalloc(sizeof(struct lttng_ust_ctx));
 		if (!*ctx_p)
-			return NULL;
+			return -ENOMEM;
+		(*ctx_p)->largest_align = 1;
 	}
 	ctx = *ctx_p;
 	if (ctx->nr_fields + 1 > ctx->allocated_fields) {
-		struct lttng_ctx_field *new_fields;
+		struct lttng_ust_ctx_field *new_fields;
 
 		ctx->allocated_fields = max_t(size_t, 1, 2 * ctx->allocated_fields);
-		new_fields = zmalloc(ctx->allocated_fields * sizeof(struct lttng_ctx_field));
+		new_fields = zmalloc(ctx->allocated_fields * sizeof(*new_fields));
 		if (!new_fields)
-			return NULL;
+			return -ENOMEM;
+		/* Copy elements */
 		if (ctx->fields)
 			memcpy(new_fields, ctx->fields, sizeof(*ctx->fields) * ctx->nr_fields);
 		free(ctx->fields);
 		ctx->fields = new_fields;
 	}
-	field = &ctx->fields[ctx->nr_fields];
 	ctx->nr_fields++;
-	return field;
+	return 0;
+}
+
+static size_t get_type_max_align(const struct lttng_ust_type_common *type)
+{
+	switch (type->type) {
+	case lttng_ust_type_integer:
+		return lttng_ust_get_type_integer(type)->alignment;
+	case lttng_ust_type_string:
+		return CHAR_BIT;
+	case lttng_ust_type_dynamic:
+		return 0;
+	case lttng_ust_type_enum:
+		return get_type_max_align(lttng_ust_get_type_enum(type)->container_type);
+	case lttng_ust_type_array:
+		return max_t(size_t, get_type_max_align(lttng_ust_get_type_array(type)->elem_type),
+				lttng_ust_get_type_array(type)->alignment);
+	case lttng_ust_type_sequence:
+		return max_t(size_t, get_type_max_align(lttng_ust_get_type_sequence(type)->elem_type),
+				lttng_ust_get_type_sequence(type)->alignment);
+	case lttng_ust_type_struct:
+	{
+		unsigned int i;
+		size_t field_align = 0;
+		const struct lttng_ust_type_struct *struct_type = lttng_ust_get_type_struct(type);
+
+		for (i = 0; i < struct_type->nr_fields; i++) {
+			field_align = max_t(size_t,
+				get_type_max_align(struct_type->fields[i]->type),
+				field_align);
+		}
+		return field_align;
+	}
+	default:
+		WARN_ON_ONCE(1);
+		return 0;
+	}
 }
 
 /*
- * Remove last context field.
+ * lttng_context_update() should be called at least once between context
+ * modification and trace start.
  */
-void lttng_remove_context_field(struct lttng_ctx **ctx_p,
-				struct lttng_ctx_field *field)
+static
+void lttng_context_update(struct lttng_ust_ctx *ctx)
 {
-	struct lttng_ctx *ctx;
+	int i;
+	size_t largest_align = 8;	/* in bits */
 
-	ctx = *ctx_p;
-	ctx->nr_fields--;
-	assert(&ctx->fields[ctx->nr_fields] == field);
-	memset(&ctx->fields[ctx->nr_fields], 0, sizeof(struct lttng_ctx_field));
+	for (i = 0; i < ctx->nr_fields; i++) {
+		size_t field_align = 8;
+
+		field_align = get_type_max_align(ctx->fields[i].event_field->type);
+		largest_align = max_t(size_t, largest_align, field_align);
+	}
+	ctx->largest_align = largest_align >> 3;	/* bits to bytes */
 }
 
-void lttng_destroy_context(struct lttng_ctx *ctx)
+int lttng_ust_context_append_rcu(struct lttng_ust_ctx **ctx_p,
+		const struct lttng_ust_ctx_field *f)
+{
+	struct lttng_ust_ctx *old_ctx = *ctx_p, *new_ctx = NULL;
+	struct lttng_ust_ctx_field *new_fields = NULL;
+	int ret;
+
+	if (old_ctx) {
+		new_ctx = zmalloc(sizeof(struct lttng_ust_ctx));
+		if (!new_ctx)
+			return -ENOMEM;
+		*new_ctx = *old_ctx;
+		new_fields = zmalloc(new_ctx->allocated_fields * sizeof(*new_fields));
+		if (!new_fields) {
+			free(new_ctx);
+			return -ENOMEM;
+		}
+		/* Copy elements */
+		memcpy(new_fields, old_ctx->fields,
+				sizeof(*old_ctx->fields) * old_ctx->nr_fields);
+		new_ctx->fields = new_fields;
+	}
+	ret = lttng_ust_context_add_field(&new_ctx);
+	if (ret) {
+		free(new_fields);
+		free(new_ctx);
+		return ret;
+	}
+	new_ctx->fields[new_ctx->nr_fields - 1] = *f;
+	lttng_context_update(new_ctx);
+	lttng_ust_rcu_assign_pointer(*ctx_p, new_ctx);
+	lttng_ust_urcu_synchronize_rcu();
+	if (old_ctx) {
+		free(old_ctx->fields);
+		free(old_ctx);
+	}
+	return 0;
+}
+
+int lttng_ust_context_append(struct lttng_ust_ctx **ctx_p,
+		const struct lttng_ust_ctx_field *f)
+{
+	int ret;
+
+	ret = lttng_ust_context_add_field(ctx_p);
+	if (ret)
+		return ret;
+	(*ctx_p)->fields[(*ctx_p)->nr_fields - 1] = *f;
+	lttng_context_update(*ctx_p);
+	return 0;
+}
+
+void lttng_destroy_context(struct lttng_ust_ctx *ctx)
 {
 	int i;
 
@@ -94,8 +234,177 @@ void lttng_destroy_context(struct lttng_ctx *ctx)
 		return;
 	for (i = 0; i < ctx->nr_fields; i++) {
 		if (ctx->fields[i].destroy)
-			ctx->fields[i].destroy(&ctx->fields[i]);
+			ctx->fields[i].destroy(ctx->fields[i].priv);
 	}
 	free(ctx->fields);
 	free(ctx);
 }
+
+/*
+ * Can be safely performed concurrently with tracing using the struct
+ * lttng_ctx. Using RCU update. Needs to match RCU read-side handling of
+ * contexts.
+ *
+ * This does not allow adding, removing, or changing typing of the
+ * contexts, since this needs to stay invariant for metadata. However,
+ * it allows updating the handlers associated with all contexts matching
+ * a provider (by name) while tracing is using it, in a way that ensures
+ * a single RCU read-side critical section see either all old, or all
+ * new handlers.
+ */
+int lttng_ust_context_set_provider_rcu(struct lttng_ust_ctx **_ctx,
+		const char *name,
+		size_t (*get_size)(void *priv, size_t offset),
+		void (*record)(void *priv, struct lttng_ust_lib_ring_buffer_ctx *ctx,
+			struct lttng_ust_channel_buffer *chan),
+		void (*get_value)(void *priv, struct lttng_ust_ctx_value *value),
+		void *priv)
+{
+	int i, ret;
+	struct lttng_ust_ctx *ctx = *_ctx, *new_ctx;
+	struct lttng_ust_ctx_field *new_fields;
+
+	if (!ctx || !lttng_find_context_provider(ctx, name))
+		return 0;
+	/*
+	 * We have at least one instance of context for the provider.
+	 */
+	new_ctx = zmalloc(sizeof(*new_ctx));
+	if (!new_ctx)
+		return -ENOMEM;
+	*new_ctx = *ctx;
+	new_fields = zmalloc(sizeof(*new_fields) * ctx->allocated_fields);
+	if (!new_fields) {
+		ret = -ENOMEM;
+		goto field_error;
+	}
+	/* Copy elements */
+	memcpy(new_fields, ctx->fields,
+		sizeof(*new_fields) * ctx->allocated_fields);
+	for (i = 0; i < ctx->nr_fields; i++) {
+		if (strncmp(new_fields[i].event_field->name,
+				name, strlen(name)) != 0)
+			continue;
+		new_fields[i].get_size = get_size;
+		new_fields[i].record = record;
+		new_fields[i].get_value = get_value;
+		new_fields[i].priv = priv;
+	}
+	new_ctx->fields = new_fields;
+	lttng_ust_rcu_assign_pointer(*_ctx, new_ctx);
+	lttng_ust_urcu_synchronize_rcu();
+	free(ctx->fields);
+	free(ctx);
+	return 0;
+
+field_error:
+	free(new_ctx);
+	return ret;
+}
+
+int lttng_context_init_all(struct lttng_ust_ctx **ctx)
+{
+	int ret;
+
+	ret = lttng_add_pthread_id_to_ctx(ctx);
+	if (ret) {
+		WARN("Cannot add context lttng_add_pthread_id_to_ctx");
+		goto error;
+	}
+	ret = lttng_add_vtid_to_ctx(ctx);
+	if (ret) {
+		WARN("Cannot add context lttng_add_vtid_to_ctx");
+		goto error;
+	}
+	ret = lttng_add_vpid_to_ctx(ctx);
+	if (ret) {
+		WARN("Cannot add context lttng_add_vpid_to_ctx");
+		goto error;
+	}
+	ret = lttng_add_procname_to_ctx(ctx);
+	if (ret) {
+		WARN("Cannot add context lttng_add_procname_to_ctx");
+		goto error;
+	}
+	ret = lttng_add_cpu_id_to_ctx(ctx);
+	if (ret) {
+		WARN("Cannot add context lttng_add_cpu_id_to_ctx");
+		goto error;
+	}
+	ret = lttng_add_cgroup_ns_to_ctx(ctx);
+	if (ret) {
+		WARN("Cannot add context lttng_add_cgroup_ns_to_ctx");
+		goto error;
+	}
+	ret = lttng_add_ipc_ns_to_ctx(ctx);
+	if (ret) {
+		WARN("Cannot add context lttng_add_ipc_ns_to_ctx");
+		goto error;
+	}
+	ret = lttng_add_mnt_ns_to_ctx(ctx);
+	if (ret) {
+		WARN("Cannot add context lttng_add_mnt_ns_to_ctx");
+		goto error;
+	}
+	ret = lttng_add_net_ns_to_ctx(ctx);
+	if (ret) {
+		WARN("Cannot add context lttng_add_net_ns_to_ctx");
+		goto error;
+	}
+	ret = lttng_add_pid_ns_to_ctx(ctx);
+	if (ret) {
+		WARN("Cannot add context lttng_add_pid_ns_to_ctx");
+		goto error;
+	}
+	ret = lttng_add_time_ns_to_ctx(ctx);
+	if (ret) {
+		WARN("Cannot add context lttng_add_time_ns_to_ctx");
+		goto error;
+	}
+	ret = lttng_add_user_ns_to_ctx(ctx);
+	if (ret) {
+		WARN("Cannot add context lttng_add_user_ns_to_ctx");
+		goto error;
+	}
+	ret = lttng_add_uts_ns_to_ctx(ctx);
+	if (ret) {
+		WARN("Cannot add context lttng_add_uts_ns_to_ctx");
+		goto error;
+	}
+	ret = lttng_add_vuid_to_ctx(ctx);
+	if (ret) {
+		WARN("Cannot add context lttng_add_vuid_to_ctx");
+		goto error;
+	}
+	ret = lttng_add_veuid_to_ctx(ctx);
+	if (ret) {
+		WARN("Cannot add context lttng_add_veuid_to_ctx");
+		goto error;
+	}
+	ret = lttng_add_vsuid_to_ctx(ctx);
+	if (ret) {
+		WARN("Cannot add context lttng_add_vsuid_to_ctx");
+		goto error;
+	}
+	ret = lttng_add_vgid_to_ctx(ctx);
+	if (ret) {
+		WARN("Cannot add context lttng_add_vgid_to_ctx");
+		goto error;
+	}
+	ret = lttng_add_vegid_to_ctx(ctx);
+	if (ret) {
+		WARN("Cannot add context lttng_add_vegid_to_ctx");
+		goto error;
+	}
+	ret = lttng_add_vsgid_to_ctx(ctx);
+	if (ret) {
+		WARN("Cannot add context lttng_add_vsgid_to_ctx");
+		goto error;
+	}
+	lttng_context_update(*ctx);
+	return 0;
+
+error:
+	lttng_destroy_context(*ctx);
+	return ret;
+}