context: document and check that only last context is removed

Merge from lttng-modules:

commit 4cae220c1be2cc73008603a21152fce7643cfc35
Author: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Date:   Sat Jul 23 12:37:54 2011 -0400

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

diff --git a/libust/ltt-context.c b/libust/ltt-context.c
index 634694b968d4c06f6cf5066b684c80efc10d68d9..030a11b0908d01c2b7174ae49c3ac6ab5e446bc9 100644 (file)
--- a/libust/ltt-context.c
+++ b/libust/ltt-context.c
@@ -45,6 +45,9 @@ 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 +55,7 @@ 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);