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Subject[tip:tracing/blktrace] blktrace: report EBUSY correctly
Commit-ID:  15152e448b693fa41de40f1e40ffbe717a3aab88
Gitweb: http://git.kernel.org/tip/15152e448b693fa41de40f1e40ffbe717a3aab88
Author: Li Zefan <lizf@cn.fujitsu.com>
AuthorDate: Fri, 20 Mar 2009 09:49:08 +0800
Committer: Ingo Molnar <mingo@elte.hu>
CommitDate: Sat, 21 Mar 2009 16:16:54 +0100

blktrace: report EBUSY correctly

blk_trace_remove_queue() returns EINVAL if q->blk_trace == NULL,
but blk_trace_setup_queue() doesn't return EBUSY if
q->blk_trace != NULL.

# echo 0 > sdaX/trace/enable
# echo 0 > sdaX/trace/enable
bash: echo: write error: Invalid argument
# echo 1 > sdaX/trace/enable
# echo 1 > sdaX/trace/enable
(should return EBUSY)
Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
Acked-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Acked-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Jens Axboe <jens.axboe@oracle.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
LKML-Reference: <49C2F614.2010101@cn.fujitsu.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>


---
kernel/trace/blktrace.c | 9 +++------
1 files changed, 3 insertions(+), 6 deletions(-)
diff --git a/kernel/trace/blktrace.c b/kernel/trace/blktrace.c
index 11e7c8d..14986af 100644
--- a/kernel/trace/blktrace.c
+++ b/kernel/trace/blktrace.c
@@ -1260,12 +1260,10 @@ static int blk_trace_remove_queue(struct request_queue *q)
static int blk_trace_setup_queue(struct request_queue *q, dev_t dev)
{
struct blk_trace *old_bt, *bt = NULL;
- int ret;

- ret = -ENOMEM;
bt = kzalloc(sizeof(*bt), GFP_KERNEL);
if (!bt)
- goto err;
+ return -ENOMEM;

bt->dev = dev;
bt->act_mask = (u16)-1;
@@ -1276,11 +1274,10 @@ static int blk_trace_setup_queue(struct request_queue *q, dev_t dev)
if (old_bt != NULL) {
(void)xchg(&q->blk_trace, old_bt);
kfree(bt);
- ret = -EBUSY;
+ return -EBUSY;
}
+
return 0;
-err:
- return ret;
}

/*

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