From: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Date: Thu, 14 Feb 2019 20:47:34 +0000 (-0500)
Subject: Cleanup vtid/vpid context caches
X-Git-Tag: v2.12.0-rc1~57
X-Git-Url: https://git.lttng.org./?a=commitdiff_plain;h=98357ffd0125c23387d42d4b706c56077392326d;p=lttng-ust.git

Cleanup vtid/vpid context caches

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
---

diff --git a/liblttng-ust/lttng-context-vpid.c b/liblttng-ust/lttng-context-vpid.c
index 53fb314b..11978e6e 100644
--- a/liblttng-ust/lttng-context-vpid.c
+++ b/liblttng-ust/lttng-context-vpid.c
@@ -34,11 +34,16 @@
 static pid_t cached_vpid;
 
 static inline
-pid_t wrapper_getpid(void)
+pid_t wrapper_getvpid(void)
 {
-	if (caa_unlikely(!cached_vpid))
-		cached_vpid = getpid();
-	return cached_vpid;
+	pid_t vpid;
+
+	vpid = CMM_LOAD_SHARED(cached_vpid);
+	if (caa_unlikely(!vpid)) {
+		vpid = getpid();
+		CMM_STORE_SHARED(cached_vpid, vpid);
+	}
+	return vpid;
 }
 
 /*
@@ -47,7 +52,7 @@ pid_t wrapper_getpid(void)
  */
 void lttng_context_vpid_reset(void)
 {
-	cached_vpid = 0;
+	CMM_STORE_SHARED(cached_vpid, 0);
 }
 
 static
@@ -65,21 +70,17 @@ void vpid_record(struct lttng_ctx_field *field,
 		 struct lttng_ust_lib_ring_buffer_ctx *ctx,
 		 struct lttng_channel *chan)
 {
-	pid_t pid;
+	pid_t vpid = wrapper_getvpid();
 
-	pid = wrapper_getpid();
-	lib_ring_buffer_align_ctx(ctx, lttng_alignof(pid));
-	chan->ops->event_write(ctx, &pid, sizeof(pid));
+	lib_ring_buffer_align_ctx(ctx, lttng_alignof(vpid));
+	chan->ops->event_write(ctx, &vpid, sizeof(vpid));
 }
 
 static
 void vpid_get_value(struct lttng_ctx_field *field,
 		struct lttng_ctx_value *value)
 {
-	pid_t pid;
-
-	pid = wrapper_getpid();
-	value->u.s64 = pid;
+	value->u.s64 = wrapper_getvpid();
 }
 
 int lttng_add_vpid_to_ctx(struct lttng_ctx **ctx)
diff --git a/liblttng-ust/lttng-context-vtid.c b/liblttng-ust/lttng-context-vtid.c
index f28e470a..5cefe953 100644
--- a/liblttng-ust/lttng-context-vtid.c
+++ b/liblttng-ust/lttng-context-vtid.c
@@ -43,7 +43,7 @@ static DEFINE_URCU_TLS(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 +56,35 @@ 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 = 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 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)