context: document and check that only last context is removed

[deliverable/lttng-modules.git] / ltt-context.c

diff --git a/ltt-context.c b/ltt-context.c
index 634694b968d4c06f6cf5066b684c80efc10d68d9..154e9966e861073e694bd9e95bb21368d90cefa2 100644 (file)
--- a/ltt-context.c
+++ b/ltt-context.c
@@ -16,6 +16,21 @@
 #include "ltt-events.h"
 #include "ltt-tracer.h"
 
+int lttng_find_context(struct lttng_ctx *ctx, const char *name)
+{
+       unsigned int i;
+
+       for (i = 0; i < ctx->nr_fields; i++) {
+               /* Skip allocated (but non-initialized) contexts */
+               if (!ctx->fields[i].event_field.name)
+                       continue;
+               if (!strcmp(ctx->fields[i].event_field.name, name))
+                       return 1;
+       }
+       return 0;
+}
+EXPORT_SYMBOL_GPL(lttng_find_context);
+
 struct lttng_ctx_field *lttng_append_context(struct lttng_ctx **ctx_p)
 {
        struct lttng_ctx_field *field;
@@ -45,6 +60,9 @@ 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 +70,7 @@ 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);