[
Jens, you want to take this one, or do you want me to?
]
From: "Steven Rostedt (VMware)" <[email protected]>
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/[email protected]
Cc: Ingo Molnar <[email protected]>
Cc: Jens Axboe <[email protected]>
Cc: [email protected]
Cc: [email protected]
Fixes: cd649b8bb830d ("blktrace: remove sysfs_blk_trace_enable_show/store()")
Reported-by: Masami Hiramatsu <[email protected]>
Tested-by: Masami Hiramatsu <[email protected]>
Signed-off-by: Steven Rostedt (VMware) <[email protected]>
---
kernel/trace/blktrace.c | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/kernel/trace/blktrace.c b/kernel/trace/blktrace.c
index b82e546083e1..614b5f0decd6 100644
--- a/kernel/trace/blktrace.c
+++ b/kernel/trace/blktrace.c
@@ -1829,6 +1829,10 @@ 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
--
2.13.6
On 8/16/18 2:08 PM, Steven Rostedt wrote:
> [
> Jens, you want to take this one, or do you want me to?
> ]
I can queue it up - done. Thanks!
--
Jens Axboe