X-Git-Url: http://git.liburcu.org/?a=blobdiff_plain;f=liblttng-ust%2Flttng-context-vtid.c;h=0a29021d4b104b3f4cb94deea5d72069dddc7145;hb=75026e9f596aa057bd3499a7be43a7fc8aa0b783;hp=8c9bbec56e67324bdaeeca71893197a58b571f38;hpb=553bbf7f38652084ed7966c7817b8ccb372b14e1;p=lttng-ust.git

diff --git a/liblttng-ust/lttng-context-vtid.c b/liblttng-ust/lttng-context-vtid.c
index 8c9bbec5..0a29021d 100644
--- a/liblttng-ust/lttng-context-vtid.c
+++ b/liblttng-ust/lttng-context-vtid.c
@@ -21,6 +21,7 @@
  */
 
 #define _LGPL_SOURCE
+#include <stddef.h>
 #include <sys/types.h>
 #include <unistd.h>
 #include <lttng/ust-events.h>
@@ -34,7 +35,7 @@
  * We cache the result to ensure we don't trigger a system call for
  * each event.
  */
-static DEFINE_URCU_TLS_IE(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
@@ -43,7 +44,7 @@ static DEFINE_URCU_TLS_IE(pid_t, cached_vtid);
  */
 void lttng_context_vtid_reset(void)
 {
-	URCU_TLS(cached_vtid) = 0;
+	CMM_STORE_SHARED(URCU_TLS(cached_vtid), 0);
 }
 
 static
@@ -56,25 +57,35 @@ size_t vtid_get_size(struct lttng_ctx_field *field, 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 = lttng_gettid();
+		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 lttng_channel *chan)
 {
-	if (caa_unlikely(!URCU_TLS(cached_vtid)))
-		URCU_TLS(cached_vtid) = gettid();
-	lib_ring_buffer_align_ctx(ctx, lttng_alignof(URCU_TLS(cached_vtid)));
-	chan->ops->event_write(ctx, &URCU_TLS(cached_vtid),
-		sizeof(URCU_TLS(cached_vtid)));
+	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(!URCU_TLS(cached_vtid)))
-		URCU_TLS(cached_vtid) = gettid();
-	value->u.s64 = URCU_TLS(cached_vtid);
+	value->u.s64 = wrapper_getvtid();
 }
 
 int lttng_add_vtid_to_ctx(struct lttng_ctx **ctx)