* [PATCH 2/2] tracing/blktrace: Fix to allow setting same value
[not found] <153441301698.6024.1680500212551396320.stgit@devbox>
@ 2018-08-16 9:51 ` Masami Hiramatsu
2018-08-16 14:38 ` Steven Rostedt
0 siblings, 1 reply; 5+ messages in thread
From: Masami Hiramatsu @ 2018-08-16 9:51 UTC (permalink / raw)
To: Steven Rostedt
Cc: Ingo Molnar, Masami Hiramatsu, linux-kernel, Jens Axboe,
linux-block
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
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: linux-block@vger.kernel.org
---
kernel/trace/blktrace.c | 11 +++++++----
1 file changed, 7 insertions(+), 4 deletions(-)
diff --git a/kernel/trace/blktrace.c b/kernel/trace/blktrace.c
index 987d9a9ae283..e67db1e8a000 100644
--- a/kernel/trace/blktrace.c
+++ b/kernel/trace/blktrace.c
@@ -1602,11 +1602,11 @@ static int blk_trace_remove_queue(struct request_queue *q)
struct blk_trace *bt;
bt = xchg(&q->blk_trace, NULL);
- if (bt == NULL)
- return -EINVAL;
+ if (bt != NULL) {
+ put_probe_ref();
+ blk_trace_free(bt);
+ }
- put_probe_ref();
- blk_trace_free(bt);
return 0;
}
@@ -1619,6 +1619,9 @@ static int blk_trace_setup_queue(struct request_queue *q,
struct blk_trace *bt = NULL;
int ret = -ENOMEM;
+ if (q->blk_trace)
+ return 0;
+
bt = kzalloc(sizeof(*bt), GFP_KERNEL);
if (!bt)
return -ENOMEM;
^ permalink raw reply related [flat|nested] 5+ messages in thread
* Re: [PATCH 2/2] tracing/blktrace: Fix to allow setting same value
2018-08-16 9:51 ` [PATCH 2/2] tracing/blktrace: Fix to allow setting same value Masami Hiramatsu
@ 2018-08-16 14:38 ` Steven Rostedt
2018-08-16 16:38 ` Masami Hiramatsu
0 siblings, 1 reply; 5+ messages in thread
From: Steven Rostedt @ 2018-08-16 14:38 UTC (permalink / raw)
To: Masami Hiramatsu; +Cc: Ingo Molnar, linux-kernel, Jens Axboe, linux-block
On Thu, 16 Aug 2018 18:51:15 +0900
Masami Hiramatsu <mhiramat@kernel.org> wrote:
> 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
>
> Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
> Cc: Jens Axboe <axboe@kernel.dk>
> Cc: linux-block@vger.kernel.org
> ---
> kernel/trace/blktrace.c | 11 +++++++----
> 1 file changed, 7 insertions(+), 4 deletions(-)
>
> diff --git a/kernel/trace/blktrace.c b/kernel/trace/blktrace.c
> index 987d9a9ae283..e67db1e8a000 100644
> --- a/kernel/trace/blktrace.c
> +++ b/kernel/trace/blktrace.c
> @@ -1602,11 +1602,11 @@ static int blk_trace_remove_queue(struct request_queue *q)
> struct blk_trace *bt;
>
> bt = xchg(&q->blk_trace, NULL);
> - if (bt == NULL)
> - return -EINVAL;
> + if (bt != NULL) {
> + put_probe_ref();
> + blk_trace_free(bt);
> + }
>
> - put_probe_ref();
> - blk_trace_free(bt);
> return 0;
> }
>
> @@ -1619,6 +1619,9 @@ static int blk_trace_setup_queue(struct request_queue *q,
> struct blk_trace *bt = NULL;
> int ret = -ENOMEM;
>
> + if (q->blk_trace)
> + return 0;
> +
> bt = kzalloc(sizeof(*bt), GFP_KERNEL);
> if (!bt)
> return -ENOMEM;
Hmm, why not just do this? Does this fix it too?
diff --git a/kernel/trace/blktrace.c b/kernel/trace/blktrace.c
index 987d9a9ae283..10b2b9c5fd25 100644
--- a/kernel/trace/blktrace.c
+++ b/kernel/trace/blktrace.c
@@ -1841,6 +1841,8 @@ 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)
+ goto out_unlock_bdev;
if (value)
ret = blk_trace_setup_queue(q, bdev);
else
-- Steve
^ permalink raw reply related [flat|nested] 5+ messages in thread
* Re: [PATCH 2/2] tracing/blktrace: Fix to allow setting same value
2018-08-16 14:38 ` Steven Rostedt
@ 2018-08-16 16:38 ` Masami Hiramatsu
2018-08-16 16:49 ` Steven Rostedt
0 siblings, 1 reply; 5+ messages in thread
From: Masami Hiramatsu @ 2018-08-16 16:38 UTC (permalink / raw)
To: Steven Rostedt; +Cc: Ingo Molnar, linux-kernel, Jens Axboe, linux-block
On Thu, 16 Aug 2018 10:38:02 -0400
Steven Rostedt <rostedt@goodmis.org> wrote:
> On Thu, 16 Aug 2018 18:51:15 +0900
> Masami Hiramatsu <mhiramat@kernel.org> wrote:
>
> > 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
> >
> > Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
> > Cc: Jens Axboe <axboe@kernel.dk>
> > Cc: linux-block@vger.kernel.org
> > ---
> > kernel/trace/blktrace.c | 11 +++++++----
> > 1 file changed, 7 insertions(+), 4 deletions(-)
> >
> > diff --git a/kernel/trace/blktrace.c b/kernel/trace/blktrace.c
> > index 987d9a9ae283..e67db1e8a000 100644
> > --- a/kernel/trace/blktrace.c
> > +++ b/kernel/trace/blktrace.c
> > @@ -1602,11 +1602,11 @@ static int blk_trace_remove_queue(struct request_queue *q)
> > struct blk_trace *bt;
> >
> > bt = xchg(&q->blk_trace, NULL);
> > - if (bt == NULL)
> > - return -EINVAL;
> > + if (bt != NULL) {
> > + put_probe_ref();
> > + blk_trace_free(bt);
> > + }
> >
> > - put_probe_ref();
> > - blk_trace_free(bt);
> > return 0;
> > }
> >
> > @@ -1619,6 +1619,9 @@ static int blk_trace_setup_queue(struct request_queue *q,
> > struct blk_trace *bt = NULL;
> > int ret = -ENOMEM;
> >
> > + if (q->blk_trace)
> > + return 0;
> > +
> > bt = kzalloc(sizeof(*bt), GFP_KERNEL);
> > if (!bt)
> > return -ENOMEM;
>
> Hmm, why not just do this? Does this fix it too?
Ah, yes, but we need to clear "ret" in that case.
Thanks!
>
> diff --git a/kernel/trace/blktrace.c b/kernel/trace/blktrace.c
> index 987d9a9ae283..10b2b9c5fd25 100644
> --- a/kernel/trace/blktrace.c
> +++ b/kernel/trace/blktrace.c
> @@ -1841,6 +1841,8 @@ 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)
> + goto out_unlock_bdev;
> if (value)
> ret = blk_trace_setup_queue(q, bdev);
> else
>
> -- Steve
--
Masami Hiramatsu <mhiramat@kernel.org>
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH 2/2] tracing/blktrace: Fix to allow setting same value
2018-08-16 16:38 ` Masami Hiramatsu
@ 2018-08-16 16:49 ` Steven Rostedt
2018-08-16 17:07 ` Masami Hiramatsu
0 siblings, 1 reply; 5+ messages in thread
From: Steven Rostedt @ 2018-08-16 16:49 UTC (permalink / raw)
To: Masami Hiramatsu; +Cc: Ingo Molnar, linux-kernel, Jens Axboe, linux-block
On Fri, 17 Aug 2018 01:38:47 +0900
Masami Hiramatsu <mhiramat@kernel.org> wrote:
> On Thu, 16 Aug 2018 10:38:02 -0400
> Steven Rostedt <rostedt@goodmis.org> wrote:
>
> > On Thu, 16 Aug 2018 18:51:15 +0900
> > Masami Hiramatsu <mhiramat@kernel.org> wrote:
> >
> > > 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
> > >
> > > Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
> > > Cc: Jens Axboe <axboe@kernel.dk>
> > > Cc: linux-block@vger.kernel.org
> > > ---
> > > kernel/trace/blktrace.c | 11 +++++++----
> > > 1 file changed, 7 insertions(+), 4 deletions(-)
> > >
> > > diff --git a/kernel/trace/blktrace.c b/kernel/trace/blktrace.c
> > > index 987d9a9ae283..e67db1e8a000 100644
> > > --- a/kernel/trace/blktrace.c
> > > +++ b/kernel/trace/blktrace.c
> > > @@ -1602,11 +1602,11 @@ static int blk_trace_remove_queue(struct request_queue *q)
> > > struct blk_trace *bt;
> > >
> > > bt = xchg(&q->blk_trace, NULL);
> > > - if (bt == NULL)
> > > - return -EINVAL;
> > > + if (bt != NULL) {
> > > + put_probe_ref();
> > > + blk_trace_free(bt);
> > > + }
> > >
> > > - put_probe_ref();
> > > - blk_trace_free(bt);
> > > return 0;
> > > }
> > >
> > > @@ -1619,6 +1619,9 @@ static int blk_trace_setup_queue(struct request_queue *q,
> > > struct blk_trace *bt = NULL;
> > > int ret = -ENOMEM;
> > >
> > > + if (q->blk_trace)
> > > + return 0;
> > > +
> > > bt = kzalloc(sizeof(*bt), GFP_KERNEL);
> > > if (!bt)
> > > return -ENOMEM;
> >
> > Hmm, why not just do this? Does this fix it too?
>
> Ah, yes, but we need to clear "ret" in that case.
Sure.
>
> Thanks!
>
> >
> > diff --git a/kernel/trace/blktrace.c b/kernel/trace/blktrace.c
> > index 987d9a9ae283..10b2b9c5fd25 100644
> > --- a/kernel/trace/blktrace.c
> > +++ b/kernel/trace/blktrace.c
> > @@ -1841,6 +1841,8 @@ 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;
+ }
-- Steve
> > if (value)
> > ret = blk_trace_setup_queue(q, bdev);
> > else
> >
> > -- Steve
>
>
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH 2/2] tracing/blktrace: Fix to allow setting same value
2018-08-16 16:49 ` Steven Rostedt
@ 2018-08-16 17:07 ` Masami Hiramatsu
0 siblings, 0 replies; 5+ messages in thread
From: Masami Hiramatsu @ 2018-08-16 17:07 UTC (permalink / raw)
To: Steven Rostedt; +Cc: Ingo Molnar, linux-kernel, Jens Axboe, linux-block
On Thu, 16 Aug 2018 12:49:17 -0400
Steven Rostedt <rostedt@goodmis.org> wrote:
> > >
> > > Hmm, why not just do this? Does this fix it too?
> >
> > Ah, yes, but we need to clear "ret" in that case.
>
> Sure.
>
> >
> > Thanks!
> >
> > >
> > > diff --git a/kernel/trace/blktrace.c b/kernel/trace/blktrace.c
> > > index 987d9a9ae283..10b2b9c5fd25 100644
> > > --- a/kernel/trace/blktrace.c
> > > +++ b/kernel/trace/blktrace.c
> > > @@ -1841,6 +1841,8 @@ 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;
> + }
>
OK, I tested and ensured that this works.
Tested-by: Masami Hiramatsu <mhiramat@kernel.org>
Thanks!
--
Masami Hiramatsu <mhiramat@kernel.org>
^ permalink raw reply [flat|nested] 5+ messages in thread
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2018-08-16 9:51 ` [PATCH 2/2] tracing/blktrace: Fix to allow setting same value Masami Hiramatsu
2018-08-16 14:38 ` Steven Rostedt
2018-08-16 16:38 ` Masami Hiramatsu
2018-08-16 16:49 ` Steven Rostedt
2018-08-16 17:07 ` Masami Hiramatsu
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