From: Emanuele Giuseppe Esposito <eesposit@redhat.com>
To: Stefan Hajnoczi <stefanha@redhat.com>
Cc: qemu-block@nongnu.org, Kevin Wolf <kwolf@redhat.com>,
Hanna Reitz <hreitz@redhat.com>,
Paolo Bonzini <pbonzini@redhat.com>, John Snow <jsnow@redhat.com>,
Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>,
Wen Congyang <wencongyang2@huawei.com>,
Xie Changlong <xiechanglong.d@gmail.com>,
Markus Armbruster <armbru@redhat.com>, Fam Zheng <fam@euphon.net>,
qemu-devel@nongnu.org
Subject: Re: [PATCH v8 05/20] job.c: add job_lock/unlock while keeping job.h intact
Date: Tue, 5 Jul 2022 10:07:40 +0200 [thread overview]
Message-ID: <0c4ff18c-f12f-6955-09b8-8acd3126492e@redhat.com> (raw)
In-Reply-To: <YsPqxG4//mc5DBn4@stefanha-x1.localdomain>
Am 05/07/2022 um 09:39 schrieb Stefan Hajnoczi:
> On Wed, Jun 29, 2022 at 10:15:23AM -0400, Emanuele Giuseppe Esposito wrote:
>> +void job_ref(Job *job)
>> +{
>> + JOB_LOCK_GUARD();
>> + job_ref_locked(job);
>> +}
>
> You don't need to fix this, but just a note:
>
> This API seems dangerous. If we don't hold the lock, how can we be sure
> job won't be unreferenced before we call job_ref()? We would need to be
> sure there exists another reference that won't be released until
> job_ref() returns...
>
I guess that's a drawback of using this new serie organization :)
This function is just a temporary placeholder to avoid having _locked
functions being called without the lock held (see previous serie
suggestions from Vladimir and Kevin).
Emanuele
next prev parent reply other threads:[~2022-07-05 8:21 UTC|newest]
Thread overview: 59+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-06-29 14:15 [PATCH v8 00/20] job: replace AioContext lock with job_mutex Emanuele Giuseppe Esposito
2022-06-29 14:15 ` [PATCH v8 01/20] job.c: make job_mutex and job_lock/unlock() public Emanuele Giuseppe Esposito
2022-06-29 14:15 ` [PATCH v8 02/20] job.h: categorize fields in struct Job Emanuele Giuseppe Esposito
2022-07-05 7:29 ` Stefan Hajnoczi
2022-06-29 14:15 ` [PATCH v8 03/20] job.c: API functions not used outside should be static Emanuele Giuseppe Esposito
2022-06-29 14:15 ` [PATCH v8 04/20] aio-wait.h: introduce AIO_WAIT_WHILE_UNLOCKED Emanuele Giuseppe Esposito
2022-06-29 14:15 ` [PATCH v8 05/20] job.c: add job_lock/unlock while keeping job.h intact Emanuele Giuseppe Esposito
2022-07-05 7:39 ` Stefan Hajnoczi
2022-07-05 8:07 ` Emanuele Giuseppe Esposito [this message]
2022-07-06 10:09 ` Stefan Hajnoczi
2022-07-05 7:39 ` Stefan Hajnoczi
2022-07-05 10:23 ` Vladimir Sementsov-Ogievskiy
2022-06-29 14:15 ` [PATCH v8 06/20] job.h: define functions called without job lock held Emanuele Giuseppe Esposito
2022-07-05 7:43 ` Stefan Hajnoczi
2022-07-05 10:53 ` Vladimir Sementsov-Ogievskiy
2022-07-06 8:22 ` Emanuele Giuseppe Esposito
2022-07-06 9:48 ` Vladimir Sementsov-Ogievskiy
2022-07-05 10:54 ` Vladimir Sementsov-Ogievskiy
2022-07-06 8:23 ` Emanuele Giuseppe Esposito
2022-07-06 9:51 ` Vladimir Sementsov-Ogievskiy
2022-06-29 14:15 ` [PATCH v8 07/20] job.h: add _locked public functions Emanuele Giuseppe Esposito
2022-07-05 7:44 ` Stefan Hajnoczi
2022-07-05 10:58 ` Vladimir Sementsov-Ogievskiy
2022-06-29 14:15 ` [PATCH v8 08/20] blockjob.h: introduce block_job _locked() APIs Emanuele Giuseppe Esposito
2022-07-05 7:58 ` Stefan Hajnoczi
2022-07-05 8:12 ` Emanuele Giuseppe Esposito
2022-07-05 15:01 ` Vladimir Sementsov-Ogievskiy
2022-07-06 12:05 ` Emanuele Giuseppe Esposito
2022-07-06 12:23 ` Vladimir Sementsov-Ogievskiy
2022-07-06 12:36 ` Emanuele Giuseppe Esposito
2022-07-06 12:59 ` Emanuele Giuseppe Esposito
2022-07-06 17:23 ` Vladimir Sementsov-Ogievskiy
2022-06-29 14:15 ` [PATCH v8 09/20] blockjob: rename notifier callbacks as _locked Emanuele Giuseppe Esposito
2022-07-05 8:00 ` Stefan Hajnoczi
2022-06-29 14:15 ` [PATCH v8 10/20] jobs: add job lock in find_* functions Emanuele Giuseppe Esposito
2022-07-05 8:03 ` Stefan Hajnoczi
2022-06-29 14:15 ` [PATCH v8 11/20] jobs: use job locks also in the unit tests Emanuele Giuseppe Esposito
2022-07-05 8:04 ` Stefan Hajnoczi
2022-06-29 14:15 ` [PATCH v8 12/20] block/mirror.c: use of job helpers in drivers to avoid TOC/TOU Emanuele Giuseppe Esposito
2022-06-29 14:15 ` [PATCH v8 13/20] jobs: group together API calls under the same job lock Emanuele Giuseppe Esposito
2022-07-05 8:14 ` Stefan Hajnoczi
2022-07-05 8:17 ` Emanuele Giuseppe Esposito
2022-07-05 13:01 ` Emanuele Giuseppe Esposito
2022-07-05 13:22 ` Vladimir Sementsov-Ogievskiy
2022-07-06 10:13 ` Stefan Hajnoczi
2022-07-05 14:55 ` Vladimir Sementsov-Ogievskiy
2022-06-29 14:15 ` [PATCH v8 14/20] commit and mirror: create new nodes using bdrv_get_aio_context, and not the job aiocontext Emanuele Giuseppe Esposito
2022-06-29 14:15 ` [PATCH v8 15/20] job: detect change of aiocontext within job coroutine Emanuele Giuseppe Esposito
2022-06-29 14:15 ` [PATCH v8 16/20] jobs: protect job.aio_context with BQL and job_mutex Emanuele Giuseppe Esposito
2022-07-05 12:44 ` Stefan Hajnoczi
2022-06-29 14:15 ` [PATCH v8 17/20] job.c: enable job lock/unlock and remove Aiocontext locks Emanuele Giuseppe Esposito
2022-07-05 13:07 ` Stefan Hajnoczi
2022-07-06 21:29 ` Emanuele Giuseppe Esposito
2022-06-29 14:15 ` [PATCH v8 18/20] block_job_query: remove atomic read Emanuele Giuseppe Esposito
2022-06-29 14:15 ` [PATCH v8 19/20] blockjob: remove unused functions Emanuele Giuseppe Esposito
2022-07-05 13:10 ` Stefan Hajnoczi
2022-06-29 14:15 ` [PATCH v8 20/20] job: " Emanuele Giuseppe Esposito
2022-07-05 13:11 ` Stefan Hajnoczi
2022-07-05 13:12 ` [PATCH v8 00/20] job: replace AioContext lock with job_mutex Stefan Hajnoczi
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