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| author | Steven Rostedt (VMware) <rostedt@goodmis.org> | 2018-08-16 16:08:37 -0400 |
|---|---|---|
| committer | Jens Axboe <axboe@kernel.dk> | 2018-08-16 14:13:56 -0600 |
| commit | 757d9140072054528b13bbe291583d9823cde195 (patch) | |
| tree | 25f616b98243cd28586096340fc467c3aab55069 /kernel/trace/blktrace.c | |
| parent | 566484a9e84c89d9875e8d5d1aac3dbc2d8f0ff4 (diff) | |
| download | linux-stable-757d9140072054528b13bbe291583d9823cde195.tar.gz linux-stable-757d9140072054528b13bbe291583d9823cde195.tar.bz2 linux-stable-757d9140072054528b13bbe291583d9823cde195.zip | |
tracing/blktrace: Fix to allow setting same value
Masami Hiramatsu reported:
Current trace-enable attribute in sysfs returns an error
if user writes the same setting value as current one,
e.g.
# cat /sys/block/sda/trace/enable
0
# echo 0 > /sys/block/sda/trace/enable
bash: echo: write error: Invalid argument
# echo 1 > /sys/block/sda/trace/enable
# echo 1 > /sys/block/sda/trace/enable
bash: echo: write error: Device or resource busy
But this is not a preferred behavior, it should ignore
if new setting is same as current one. This fixes the
problem as below.
# cat /sys/block/sda/trace/enable
0
# echo 0 > /sys/block/sda/trace/enable
# echo 1 > /sys/block/sda/trace/enable
# echo 1 > /sys/block/sda/trace/enable
Link: http://lkml.kernel.org/r/20180816103802.08678002@gandalf.local.home
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: linux-block@vger.kernel.org
Cc: stable@vger.kernel.org
Fixes: cd649b8bb830d ("blktrace: remove sysfs_blk_trace_enable_show/store()")
Reported-by: Masami Hiramatsu <mhiramat@kernel.org>
Tested-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'kernel/trace/blktrace.c')
| -rw-r--r-- | kernel/trace/blktrace.c | 4 |
1 files changed, 4 insertions, 0 deletions
diff --git a/kernel/trace/blktrace.c b/kernel/trace/blktrace.c index b951aa1fac61..96457ad8d720 100644 --- a/kernel/trace/blktrace.c +++ b/kernel/trace/blktrace.c @@ -1841,6 +1841,10 @@ static ssize_t sysfs_blk_trace_attr_store(struct device *dev, mutex_lock(&q->blk_trace_mutex); if (attr == &dev_attr_enable) { + if (!!value == !!q->blk_trace) { + ret = 0; + goto out_unlock_bdev; + } if (value) ret = blk_trace_setup_queue(q, bdev); else |