[PATCH for-6.1? v2 6/7] mirror: Check job_is_cancelled() earlier

Max Reitz posted 7 patches 4 years, 6 months ago
Maintainers: Eric Blake <eblake@redhat.com>, John Snow <jsnow@redhat.com>, Markus Armbruster <armbru@redhat.com>, Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>, Xie Changlong <xiechanglong.d@gmail.com>, Kevin Wolf <kwolf@redhat.com>, Wen Congyang <wencongyang2@huawei.com>, Max Reitz <mreitz@redhat.com>
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[PATCH for-6.1? v2 6/7] mirror: Check job_is_cancelled() earlier
Posted by Max Reitz 4 years, 6 months ago
We must check whether the job is force-cancelled early in our main loop,
most importantly before any `continue` statement.  For example, we used
to have `continue`s before our current checking location that are
triggered by `mirror_flush()` failing.  So, if `mirror_flush()` kept
failing, force-cancelling the job would not terminate it.

A job being force-cancelled should be treated the same as the job having
failed, so put the check in the same place where we check `s->ret < 0`.

Buglink: https://gitlab.com/qemu-project/qemu/-/issues/462
Signed-off-by: Max Reitz <mreitz@redhat.com>
---
 block/mirror.c | 7 +------
 1 file changed, 1 insertion(+), 6 deletions(-)

diff --git a/block/mirror.c b/block/mirror.c
index 72e02fa34e..46d1a1e5a2 100644
--- a/block/mirror.c
+++ b/block/mirror.c
@@ -993,7 +993,7 @@ static int coroutine_fn mirror_run(Job *job, Error **errp)
             mirror_wait_for_any_operation(s, true);
         }
 
-        if (s->ret < 0) {
+        if (s->ret < 0 || job_is_cancelled(&s->common.job)) {
             ret = s->ret;
             goto immediate_exit;
         }
@@ -1078,8 +1078,6 @@ static int coroutine_fn mirror_run(Job *job, Error **errp)
             break;
         }
 
-        ret = 0;
-
         if (job_is_ready(&s->common.job) && !should_complete) {
             delay_ns = (s->in_flight == 0 &&
                         cnt == 0 ? BLOCK_JOB_SLICE_TIME : 0);
@@ -1087,9 +1085,6 @@ static int coroutine_fn mirror_run(Job *job, Error **errp)
         trace_mirror_before_sleep(s, cnt, job_is_ready(&s->common.job),
                                   delay_ns);
         job_sleep_ns(&s->common.job, delay_ns);
-        if (job_is_cancelled(&s->common.job)) {
-            break;
-        }
         s->last_pause_ns = qemu_clock_get_ns(QEMU_CLOCK_REALTIME);
     }
 
-- 
2.31.1


Re: [PATCH for-6.1? v2 6/7] mirror: Check job_is_cancelled() earlier
Posted by Vladimir Sementsov-Ogievskiy 4 years, 6 months ago
26.07.2021 17:46, Max Reitz wrote:
> We must check whether the job is force-cancelled early in our main loop,
> most importantly before any `continue` statement.  For example, we used
> to have `continue`s before our current checking location that are
> triggered by `mirror_flush()` failing.  So, if `mirror_flush()` kept
> failing, force-cancelling the job would not terminate it.
> 
> A job being force-cancelled should be treated the same as the job having
> failed, so put the check in the same place where we check `s->ret < 0`.
> 
> Buglink: https://gitlab.com/qemu-project/qemu/-/issues/462
> Signed-off-by: Max Reitz <mreitz@redhat.com>
> ---
>   block/mirror.c | 7 +------
>   1 file changed, 1 insertion(+), 6 deletions(-)
> 
> diff --git a/block/mirror.c b/block/mirror.c
> index 72e02fa34e..46d1a1e5a2 100644
> --- a/block/mirror.c
> +++ b/block/mirror.c
> @@ -993,7 +993,7 @@ static int coroutine_fn mirror_run(Job *job, Error **errp)
>               mirror_wait_for_any_operation(s, true);
>           }
>   
> -        if (s->ret < 0) {
> +        if (s->ret < 0 || job_is_cancelled(&s->common.job)) {
>               ret = s->ret;
>               goto immediate_exit;
>           }
> @@ -1078,8 +1078,6 @@ static int coroutine_fn mirror_run(Job *job, Error **errp)
>               break;
>           }
>   
> -        ret = 0;
> -

That's just a cleanup, that statement is useless pre-patch, yes?

>           if (job_is_ready(&s->common.job) && !should_complete) {
>               delay_ns = (s->in_flight == 0 &&
>                           cnt == 0 ? BLOCK_JOB_SLICE_TIME : 0);
> @@ -1087,9 +1085,6 @@ static int coroutine_fn mirror_run(Job *job, Error **errp)
>           trace_mirror_before_sleep(s, cnt, job_is_ready(&s->common.job),
>                                     delay_ns);
>           job_sleep_ns(&s->common.job, delay_ns);
> -        if (job_is_cancelled(&s->common.job)) {
> -            break;
> -        }
>           s->last_pause_ns = qemu_clock_get_ns(QEMU_CLOCK_REALTIME);
>       }
>   
> 

Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>

-- 
Best regards,
Vladimir

Re: [PATCH for-6.1? v2 6/7] mirror: Check job_is_cancelled() earlier
Posted by Max Reitz 4 years, 6 months ago
On 27.07.21 15:13, Vladimir Sementsov-Ogievskiy wrote:
> 26.07.2021 17:46, Max Reitz wrote:
>> We must check whether the job is force-cancelled early in our main loop,
>> most importantly before any `continue` statement.  For example, we used
>> to have `continue`s before our current checking location that are
>> triggered by `mirror_flush()` failing.  So, if `mirror_flush()` kept
>> failing, force-cancelling the job would not terminate it.
>>
>> A job being force-cancelled should be treated the same as the job having
>> failed, so put the check in the same place where we check `s->ret < 0`.
>>
>> Buglink: https://gitlab.com/qemu-project/qemu/-/issues/462
>> Signed-off-by: Max Reitz <mreitz@redhat.com>
>> ---
>>   block/mirror.c | 7 +------
>>   1 file changed, 1 insertion(+), 6 deletions(-)
>>
>> diff --git a/block/mirror.c b/block/mirror.c
>> index 72e02fa34e..46d1a1e5a2 100644
>> --- a/block/mirror.c
>> +++ b/block/mirror.c
>> @@ -993,7 +993,7 @@ static int coroutine_fn mirror_run(Job *job, 
>> Error **errp)
>>               mirror_wait_for_any_operation(s, true);
>>           }
>>   -        if (s->ret < 0) {
>> +        if (s->ret < 0 || job_is_cancelled(&s->common.job)) {
>>               ret = s->ret;
>>               goto immediate_exit;
>>           }
>> @@ -1078,8 +1078,6 @@ static int coroutine_fn mirror_run(Job *job, 
>> Error **errp)
>>               break;
>>           }
>>   -        ret = 0;
>> -
>
> That's just a cleanup, that statement is useless pre-patch, yes?

I think it was intended for if we left this loop via the 
job_is_cancelled() condition below.  Since it’s removed, this statement 
seems meaningless, so I removed it along with the `break`.

Max

>
>>           if (job_is_ready(&s->common.job) && !should_complete) {
>>               delay_ns = (s->in_flight == 0 &&
>>                           cnt == 0 ? BLOCK_JOB_SLICE_TIME : 0);
>> @@ -1087,9 +1085,6 @@ static int coroutine_fn mirror_run(Job *job, 
>> Error **errp)
>>           trace_mirror_before_sleep(s, cnt, 
>> job_is_ready(&s->common.job),
>>                                     delay_ns);
>>           job_sleep_ns(&s->common.job, delay_ns);
>> -        if (job_is_cancelled(&s->common.job)) {
>> -            break;
>> -        }
>>           s->last_pause_ns = qemu_clock_get_ns(QEMU_CLOCK_REALTIME);
>>       }
>>
>
> Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
>