Re: [PATCH v9 19/21] blockjob: protect iostatus field in BlockJob struct

[Emanuele Giuseppe Esposito <eesposit@redhat.com>]

Am 20/07/2022 um 15:15 schrieb Vladimir Sementsov-Ogievskiy:
> On 7/19/22 16:07, Emanuele Giuseppe Esposito wrote:
>>
>>
>> Am 11/07/2022 um 16:51 schrieb Vladimir Sementsov-Ogievskiy:
>>> On 7/6/22 23:15, Emanuele Giuseppe Esposito wrote:
>>>> iostatus is the only field (together with .job) that needs
>>>> protection using the job mutex.
>>>>
>>>> It is set in the main loop (GLOBAL_STATE functions) but read
>>>> in I/O code (block_job_error_action).
>>>>
>>>> In order to protect it, change block_job_iostatus_set_err
>>>> to block_job_iostatus_set_err_locked(), always called under
>>>> job lock.
>>>>
>>>> Signed-off-by: Emanuele Giuseppe Esposito <eesposit@redhat.com>
>>>
>>> Seems, that (and previous) patch should go before 15.
>>
>> Why?
> 
> As I understand, before patch 15 everything was protected by aio-context
> lock. After patch 15, this becomes a bug, which we fix now. If we do it
> before patch 15, we never introduce the bug.. Or what I miss?

Makes sense.

Emanuele

> 
>>
>>>
>>>> ---
>>>>    blockjob.c | 5 +++--
>>>>    1 file changed, 3 insertions(+), 2 deletions(-)
>>>>
>>>> diff --git a/blockjob.c b/blockjob.c
>>>> index a2559b97a7..893c8ff08e 100644
>>>> --- a/blockjob.c
>>>> +++ b/blockjob.c
>>>> @@ -367,7 +367,8 @@ BlockJobInfo *block_job_query(BlockJob *job, Error
>>>> **errp)
>>>>        return block_job_query_locked(job, errp);
>>>>    }
>>>>    -static void block_job_iostatus_set_err(BlockJob *job, int error)
>>>> +/* Called with job lock held */
>>>> +static void block_job_iostatus_set_err_locked(BlockJob *job, int
>>>> error)
>>>>    {
>>>>        if (job->iostatus == BLOCK_DEVICE_IO_STATUS_OK) {
>>>>            job->iostatus = error == ENOSPC ?
>>>> BLOCK_DEVICE_IO_STATUS_NOSPACE :
>>>> @@ -586,8 +587,8 @@ BlockErrorAction block_job_error_action(BlockJob
>>>> *job, BlockdevOnError on_err,
>>>>                     */
>>>>                    job->job.user_paused = true;
>>>>                }
>>>> +            block_job_iostatus_set_err_locked(job, error);
>>>>            }
>>>> -        block_job_iostatus_set_err(job, error);
>>>>        }
>>>>        return action;
>>>>    }
>>>
>>>
>>
> 
>