Add ring buffer comment about shm

[lttng-ust.git] / libust / ltt-context.c

diff --git a/libust/ltt-context.c b/libust/ltt-context.c
index 634694b968d4c06f6cf5066b684c80efc10d68d9..dd526542be8f518ef4d625d8908be4e05109c1b6 100644 (file)
--- a/libust/ltt-context.c
+++ b/libust/ltt-context.c
@@ -12,10 +12,13 @@
 #include <linux/list.h>
 #include <linux/mutex.h>
 #include <linux/slab.h>
+#include <ust/lttng-events.h>
 #include "wrapper/vmalloc.h"   /* for wrapper_vmalloc_sync_all() */
-#include "ltt-events.h"
 #include "ltt-tracer.h"
 
+/*
+ * Note: as we append context information, the pointer location may change.
+ */
 struct lttng_ctx_field *lttng_append_context(struct lttng_ctx **ctx_p)
 {
        struct lttng_ctx_field *field;
@@ -45,6 +48,9 @@ struct lttng_ctx_field *lttng_append_context(struct lttng_ctx **ctx_p)
 }
 EXPORT_SYMBOL_GPL(lttng_append_context);
 
+/*
+ * Remove last context field.
+ */
 void lttng_remove_context_field(struct lttng_ctx **ctx_p,
                                struct lttng_ctx_field *field)
 {
@@ -52,6 +58,7 @@ void lttng_remove_context_field(struct lttng_ctx **ctx_p,
 
        ctx = *ctx_p;
        ctx->nr_fields--;
+       WARN_ON_ONCE(&ctx->fields[ctx->nr_fields] != field);
        memset(&ctx->fields[ctx->nr_fields], 0, sizeof(struct lttng_ctx_field));
 }
 EXPORT_SYMBOL_GPL(lttng_remove_context_field);