Commit-ID: a216c4acfafb28d697fe07b4137ab780131e4d60
Gitweb: http://git.kernel.org/tip/a216c4acfafb28d697fe07b4137ab780131e4d60
Author: Li Zefan <lizf@xxxxxxxxxxxxxx>
AuthorDate: Wed, 25 Mar 2009 17:19:33 +0800
Committer: Ingo Molnar <mingo@xxxxxxx>
CommitDate: Wed, 25 Mar 2009 12:05:39 +0100
blktrace: fix a race when creating blk_tree_root in debugfs
t1 t2
------ ------
do_blk_trace_setup() do_blk_trace_setup()
if (!blk_tree_root) {
if (!blk_tree_root)
blk_tree_root = create_dir()
blk_tree_root = create_dir();
(now blk_tree_root == NULL)
...
dir = create_dir(name, blk_tree_root);
Due to this race, t1 will create 'dir' in /debugfs but not /debugfs/block.
Signed-off-by: Li Zefan <lizf@xxxxxxxxxxxxxx>
Acked-by: Jens Axboe <jens.axboe@xxxxxxxxxx>
Cc: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
Cc: Steven Rostedt <rostedt@xxxxxxxxxxx>
Cc: Frederic Weisbecker <fweisbec@xxxxxxxxx>
LKML-Reference: <49C9F725.9080409@xxxxxxxxxxxxxx>
Signed-off-by: Ingo Molnar <mingo@xxxxxxx>
---
kernel/trace/blktrace.c | 6 +++++-
1 files changed, 5 insertions(+), 1 deletions(-)
diff --git a/kernel/trace/blktrace.c b/kernel/trace/blktrace.c
index ee7a8bb..95f89fa 100644
--- a/kernel/trace/blktrace.c
+++ b/kernel/trace/blktrace.c
@@ -426,11 +426,15 @@ int do_blk_trace_setup(struct request_queue *q, char *name, dev_t dev,
ret = -ENOENT;
+ mutex_lock(&blk_tree_mutex);
if (!blk_tree_root) {
blk_tree_root = debugfs_create_dir("block", NULL);
- if (!blk_tree_root)
+ if (!blk_tree_root) {
+ mutex_unlock(&blk_tree_mutex);
goto err;
+ }
}
+ mutex_unlock(&blk_tree_mutex);
dir = debugfs_create_dir(buts->name, blk_tree_root);
--
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