X-Git-Url: http://git.lttng.org/?a=blobdiff_plain;f=liblttng-ust%2Flttng-context-vtid.c;h=5cefe9538486a38ffba957fe06b8601b907ff744;hb=98357ffd0125c23387d42d4b706c56077392326d;hp=d5664c951cf708ff2b7ac6e9be4ca3b61fbbe87b;hpb=e92f3e285939848f248af08f11a39a04a7fcf852;p=lttng-ust.git

diff --git a/liblttng-ust/lttng-context-vtid.c b/liblttng-ust/lttng-context-vtid.c
index d5664c95..5cefe953 100644
--- a/liblttng-ust/lttng-context-vtid.c
+++ b/liblttng-ust/lttng-context-vtid.c
@@ -20,37 +20,21 @@
  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  */
 
+#define _LGPL_SOURCE
 #include <sys/types.h>
 #include <unistd.h>
 #include <lttng/ust-events.h>
 #include <lttng/ust-tracer.h>
 #include <lttng/ringbuffer-config.h>
-#include "ltt-tracer-core.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 <lttng/ust-tid.h>
+#include <urcu/tls-compat.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
@@ -59,11 +43,11 @@ static __thread pid_t cached_vtid;
  */
 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(struct lttng_ctx_field *field, size_t offset)
 {
 	size_t size = 0;
 
@@ -72,15 +56,35 @@ size_t vtid_get_size(size_t offset)
 	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 = getpid();
+		CMM_STORE_SHARED(URCU_TLS(cached_vtid), vtid);
+	}
+	return vtid;
+}
+
 static
 void vtid_record(struct lttng_ctx_field *field,
 		 struct lttng_ust_lib_ring_buffer_ctx *ctx,
-		 struct ltt_channel *chan)
+		 struct lttng_channel *chan)
+{
+	pid_t vtid = wrapper_getvtid();
+
+	lib_ring_buffer_align_ctx(ctx, lttng_alignof(vtid));
+	chan->ops->event_write(ctx, &vtid, sizeof(vtid));
+}
+
+static
+void vtid_get_value(struct lttng_ctx_field *field,
+		struct lttng_ctx_value *value)
 {
-	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));
+	value->u.s64 = wrapper_getvtid();
 }
 
 int lttng_add_vtid_to_ctx(struct lttng_ctx **ctx)
@@ -104,6 +108,8 @@ int lttng_add_vtid_to_ctx(struct lttng_ctx **ctx)
 	field->event_field.type.u.basic.integer.encoding = lttng_encode_none;
 	field->get_size = vtid_get_size;
 	field->record = vtid_record;
+	field->get_value = vtid_get_value;
+	lttng_context_update(*ctx);
 	return 0;
 }
 
@@ -112,5 +118,5 @@ int lttng_add_vtid_to_ctx(struct lttng_ctx **ctx)
  */
 void lttng_fixup_vtid_tls(void)
 {
-	asm volatile ("" : : "m" (cached_vtid));
+	asm volatile ("" : : "m" (URCU_TLS(cached_vtid)));
 }