tracing: Handle tracing_map_alloc_elts() error path correctly

If tracing_map_elt_alloc() fails, it will return ERR_PTR() instead of
NULL, so change the check to IS_ERROR().  We also need to set the
failed entry in the map->elts array to NULL instead of ERR_PTR() so
tracing_map_free_elts() doesn't try freeing an ERR_PTR().

tracing_map_free_elts() should also zero out what it frees so a
reentrant call won't find previously freed elements.

Link: http://lkml.kernel.org/r/f29d03b00bce3aac8cf151a8a30e6c83e5fee66d.1461610073.git.tom.zanussi@linux.intel.com
Signed-off-by: Tom Zanussi <tom.zanussi@linux.intel.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

diff --git a/kernel/trace/tracing_map.c b/kernel/trace/tracing_map.c
index e7dfc5eec6698d0b9c13f08f51c14aa9d99b20dd..0a689bbb78ef4fe48d9e55cb867e836aea87a726 100644 (file)
--- a/kernel/trace/tracing_map.c
+++ b/kernel/trace/tracing_map.c
@@ -366,10 +366,13 @@ static void tracing_map_free_elts(struct tracing_map *map)
        if (!map->elts)
                return;
 
-       for (i = 0; i < map->max_elts; i++)
+       for (i = 0; i < map->max_elts; i++) {
                tracing_map_elt_free(*(TRACING_MAP_ELT(map->elts, i)));
+               *(TRACING_MAP_ELT(map->elts, i)) = NULL;
+       }
 
        tracing_map_array_free(map->elts);
+       map->elts = NULL;
 }
 
 static int tracing_map_alloc_elts(struct tracing_map *map)
@@ -383,7 +386,8 @@ static int tracing_map_alloc_elts(struct tracing_map *map)
 
        for (i = 0; i < map->max_elts; i++) {
                *(TRACING_MAP_ELT(map->elts, i)) = tracing_map_elt_alloc(map);
-               if (!(*(TRACING_MAP_ELT(map->elts, i)))) {
+               if (IS_ERR(*(TRACING_MAP_ELT(map->elts, i)))) {
+                       *(TRACING_MAP_ELT(map->elts, i)) = NULL;
                        tracing_map_free_elts(map);
 
                        return -ENOMEM;