From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:44905) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1brUZJ-0003jr-Ua for qemu-devel@nongnu.org; Tue, 04 Oct 2016 14:36:02 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1brUZH-0006mI-Ae for qemu-devel@nongnu.org; Tue, 04 Oct 2016 14:35:56 -0400 References: <1475272849-19990-1-git-send-email-jsnow@redhat.com> <1475272849-19990-4-git-send-email-jsnow@redhat.com> <20161004005709.GB21979@localhost.localdomain> From: John Snow Message-ID: <3d3ab813-3f22-1b02-a0bb-30d16bbef89f@redhat.com> Date: Tue, 4 Oct 2016 14:35:39 -0400 MIME-Version: 1.0 In-Reply-To: <20161004005709.GB21979@localhost.localdomain> Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH v2 03/11] Blockjobs: Internalize user_pause logic List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Jeff Cody Cc: kwolf@redhat.com, vsementsov@virtuozzo.com, famz@redhat.com, qemu-block@nongnu.org, qemu-devel@nongnu.org, stefanha@redhat.com On 10/03/2016 08:57 PM, Jeff Cody wrote: > On Fri, Sep 30, 2016 at 06:00:41PM -0400, John Snow wrote: >> BlockJobs will begin hiding their state in preparation for some >> refactorings anyway, so let's internalize the user_pause mechanism >> instead of leaving it to callers to correctly manage. >> >> Signed-off-by: John Snow >> --- >> block/io.c | 2 +- >> blockdev.c | 10 ++++------ >> blockjob.c | 16 ++++++++++++---- >> include/block/blockjob.h | 11 ++++++++++- >> 4 files changed, 27 insertions(+), 12 deletions(-) >> >> diff --git a/block/io.c b/block/io.c >> index fdf7080..868b065 100644 >> --- a/block/io.c >> +++ b/block/io.c >> @@ -291,7 +291,7 @@ void bdrv_drain_all(void) >> AioContext *aio_context = blk_get_aio_context(job->blk); >> >> aio_context_acquire(aio_context); >> - block_job_pause(job); >> + block_job_pause(job, false); > > Hmm. Maybe semantically, an enum might work better here than a bool. When > I see "block_job_pause(job, false)", it reads like you just un-paused the > job, rather than paused it with some contextual info. Perhaps > JOB_USER_PAUSE and JOB_SYS_PAUSE (or just JOB_USER and JOB_SYS)? > >> aio_context_release(aio_context); >> } >> >> diff --git a/blockdev.c b/blockdev.c >> index 03200e7..268452f 100644 >> --- a/blockdev.c >> +++ b/blockdev.c >> @@ -3629,7 +3629,7 @@ void qmp_block_job_cancel(const char *device, >> force = false; >> } >> >> - if (job->user_paused && !force) { >> + if (block_job_paused(job) && !force) { >> error_setg(errp, "The block job for device '%s' is currently paused", >> device); >> goto out; >> @@ -3646,13 +3646,12 @@ void qmp_block_job_pause(const char *device, Error **errp) >> AioContext *aio_context; >> BlockJob *job = find_block_job(device, &aio_context, errp); >> >> - if (!job || job->user_paused) { >> + if (!job || block_job_paused(job)) { >> return; >> } >> >> - job->user_paused = true; >> trace_qmp_block_job_pause(job); >> - block_job_pause(job); >> + block_job_pause(job, true); >> aio_context_release(aio_context); >> } >> >> @@ -3661,11 +3660,10 @@ void qmp_block_job_resume(const char *device, Error **errp) >> AioContext *aio_context; >> BlockJob *job = find_block_job(device, &aio_context, errp); >> >> - if (!job || !job->user_paused) { >> + if (!job || !block_job_paused(job)) { >> return; >> } >> >> - job->user_paused = false; >> trace_qmp_block_job_resume(job); >> block_job_iostatus_reset(job); >> block_job_resume(job); >> diff --git a/blockjob.c b/blockjob.c >> index 6a300ba..2a35f50 100644 >> --- a/blockjob.c >> +++ b/blockjob.c >> @@ -104,7 +104,7 @@ static void block_job_detach_aio_context(void *opaque) >> /* In case the job terminates during aio_poll()... */ >> block_job_ref(job); >> >> - block_job_pause(job); >> + block_job_pause(job, false); >> >> if (!job->paused) { >> /* If job is !job->busy this kicks it into the next pause point. */ >> @@ -343,9 +343,12 @@ void block_job_complete(BlockJob *job, Error **errp) >> job->driver->complete(job, errp); >> } >> >> -void block_job_pause(BlockJob *job) >> +void block_job_pause(BlockJob *job, bool user) >> { >> job->pause_count++; >> + if (user) { >> + job->user_paused = true; >> + } >> } >> >> static bool block_job_should_pause(BlockJob *job) >> @@ -353,6 +356,11 @@ static bool block_job_should_pause(BlockJob *job) >> return job->pause_count > 0; >> } >> >> +bool block_job_paused(BlockJob *job) > > I think a more apt name for this would be "block_job_user_paused()", because > it doesn't tell if the job is paused per se, but only if it is paused by a > user. > Done. >> +{ >> + return job ? job->user_paused : 0; >> +} >> + >> void coroutine_fn block_job_pause_point(BlockJob *job) >> { >> if (!block_job_should_pause(job)) { >> @@ -386,6 +394,7 @@ void block_job_resume(BlockJob *job) >> if (job->pause_count) { >> return; >> } >> + job->user_paused = false; > > At first I was thinking block_job_resume() would need a way of knowing if it > was a user resume, similar to block_job_pause(). But I guess not... if the > user paused it, then job->pause_count should always be > 0, I think. > > But wait...could we ever get into a state where something like this happens: > > block_job_pause(job, true); /* user paused */ > > [...] > > block_job_pause(job, false); /* system paused */ > > [...] > > block_job_resume(job); /* user resumes */ > > [...] /* job->user_paused is still true, although it shouldn't be */ > > block_job_resume(job); /* system resumes */ > > /* now job->user_paused is false */ > > I decided to fix both problems by just having a block_job_user_pause() and a block_job_user_resume(). I'll wait for more reviews before I send out the v2. >> block_job_enter(job); >> } >> >> @@ -592,8 +601,7 @@ BlockErrorAction block_job_error_action(BlockJob *job, BlockdevOnError on_err, >> action, &error_abort); >> if (action == BLOCK_ERROR_ACTION_STOP) { >> /* make the pause user visible, which will be resumed from QMP. */ >> - job->user_paused = true; >> - block_job_pause(job); >> + block_job_pause(job, true); >> block_job_iostatus_set_err(job, error); >> } >> return action; >> diff --git a/include/block/blockjob.h b/include/block/blockjob.h >> index 4ddb4ae..081f6c2 100644 >> --- a/include/block/blockjob.h >> +++ b/include/block/blockjob.h >> @@ -347,10 +347,19 @@ void coroutine_fn block_job_pause_point(BlockJob *job); >> /** >> * block_job_pause: >> * @job: The job to be paused. >> + * @user: Requested explicitly via user? >> * >> * Asynchronously pause the specified job. >> */ >> -void block_job_pause(BlockJob *job); >> +void block_job_pause(BlockJob *job, bool user); >> + >> +/** >> + * block_job_paused: >> + * @job: The job to query. >> + * >> + * Returns true if the job is user-paused. >> + */ >> +bool block_job_paused(BlockJob *job); >> >> /** >> * block_job_resume: >> -- >> 2.7.4 >> > --js