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authorLi Zefan <lizf@cn.fujitsu.com>2009-03-25 17:19:33 +0800
committerIngo Molnar <mingo@elte.hu>2009-03-31 17:26:59 +0200
commitb5230b56ee6caeb27cedb7753c0c319646383bb4 (patch)
treea8cb9730ba9d89346d3bd959393e72c84b36ce84 /kernel/trace
parent6c051ce0307526adec32a847f0daa1af2124f0a9 (diff)
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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@cn.fujitsu.com> Acked-by: Jens Axboe <jens.axboe@oracle.com> Cc: Arnaldo Carvalho de Melo <acme@redhat.com> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Frederic Weisbecker <fweisbec@gmail.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'kernel/trace')
-rw-r--r--kernel/trace/blktrace.c6
1 files changed, 5 insertions, 1 deletions
diff --git a/kernel/trace/blktrace.c b/kernel/trace/blktrace.c
index ee7a8bb8b1e..95f89faca73 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);