+++ /dev/null
-/*
- * SPDX-License-Identifier: LGPL-2.1-only
- *
- * Copyright (C) 2009-2012 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
- *
- * 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-context.h>
-#include <ust-tid.h>
-#include <urcu/tls-compat.h>
-
-#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 DEFINE_URCU_TLS(pid_t, cached_vtid);
-
-/*
- * Upon fork or clone, the TID assigned to our thread is not the same as
- * we kept in cache. Luckily, we are the only thread surviving in the
- * child process, so we can simply clear our cached version.
- */
-void lttng_context_vtid_reset(void)
-{
- CMM_STORE_SHARED(URCU_TLS(cached_vtid), 0);
-}
-
-static
-size_t vtid_get_size(struct lttng_ust_ctx_field *field, size_t offset)
-{
- size_t size = 0;
-
- 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_ust_ctx_field *field,
- struct lttng_ust_lib_ring_buffer_ctx *ctx,
- struct lttng_ust_channel_buffer *chan)
-{
- pid_t vtid = wrapper_getvtid();
-
- chan->ops->event_write(ctx, &vtid, sizeof(vtid), lttng_ust_rb_alignof(vtid));
-}
-
-static
-void vtid_get_value(struct lttng_ust_ctx_field *field,
- struct lttng_ust_ctx_value *value)
-{
- value->u.s64 = wrapper_getvtid();
-}
-
-int lttng_add_vtid_to_ctx(struct lttng_ust_ctx **ctx)
-{
- struct lttng_ust_ctx_field *field;
- struct lttng_ust_type_common *type;
- int ret;
-
- type = lttng_ust_create_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);
- if (!type)
- return -ENOMEM;
- field = lttng_append_context(ctx);
- if (!field) {
- ret = -ENOMEM;
- goto error_context;
- }
- if (lttng_find_context(*ctx, "vtid")) {
- ret = -EEXIST;
- goto error_find_context;
- }
- field->event_field->name = strdup("vtid");
- if (!field->event_field->name) {
- ret = -ENOMEM;
- goto error_name;
- }
- field->event_field->type = type;
- field->get_size = vtid_get_size;
- field->record = vtid_record;
- field->get_value = vtid_get_value;
- lttng_context_update(*ctx);
- return 0;
-
-error_name:
-error_find_context:
- lttng_remove_context_field(ctx, field);
-error_context:
- lttng_ust_destroy_type(type);
- 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)));
-}