Cleanup vtid/vpid context caches

[lttng-ust.git] / liblttng-ust / lttng-context-vpid.c

diff --git a/liblttng-ust/lttng-context-vpid.c b/liblttng-ust/lttng-context-vpid.c
index 53fb314b8c0da1bdf353f00c59c953879b4ed150..11978e6e33d8e0f93ac4fb0bd34e12495790d7e4 100644 (file)
--- 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)