Re: [PATCH v8 08/20] blockjob.h: introduce block_job _locked() APIs

[Vladimir Sementsov-Ogievskiy]

On 7/6/22 15:05, Emanuele Giuseppe Esposito wrote:
> Am 05/07/2022 um 17:01 schrieb Vladimir Sementsov-Ogievskiy:
> > On 6/29/22 17:15, Emanuele Giuseppe Esposito wrote:
> > > Just as done with job.h, create _locked() functions in blockjob.h
> >
> > We modify not only blockjob.h, I'd s/blockjob.h/blockjob/ in subject.
> >
> > Also, we start to introduce _locked block_job_* APIs.
> >
> > Does it mean that BlockJob and Job share the global mutex to protect
> > themselves? Than I think we should document in BlockJob struct what is
> > protected by job_mutex.
>
> There is nothing in the struct (apart from Job) that is protected by the
> job lock. I can add a comment "Protected by job mutex" on top of Job job
> field?

Yes, I think that's worth doing.

Other fields doesn't need the lock?

> > And please, let's be consistent on whether we add or not add "with mutex
> > held" / "with mutex not held" comments. For job API you mostly add it
> > for each function.. Let's do same here? Same for "temporary unlock"
> > comments.
>
> Where did I miss the mutex lock/unlock comments? Yes I forgot the
> "temporary unlock" thing but apart from that all functions have a
> comment saying if they take the lock or not.

Probably that's my impression because you add some comments in separate 
patches. OK.

> > > These functions will be later useful when caller has already taken
> > > the lock. All blockjob _locked functions call job _locked functions.
> > >
> > > Note: at this stage, job_{lock/unlock} and job lock guard macros
> > > are *nop*.
> > >
> > > Signed-off-by: Emanuele Giuseppe Esposito <eesposit@redhat.com>
> > > ---
> > >    blockjob.c               | 52 ++++++++++++++++++++++++++++++++--------
> > >    include/block/blockjob.h | 15 ++++++++++++
> > >    2 files changed, 57 insertions(+), 10 deletions(-)
> > >
> > > diff --git a/blockjob.c b/blockjob.c
> > > index 7da59a1f1c..0d59aba439 100644
> > > --- a/blockjob.c
> > > +++ b/blockjob.c
> > > @@ -44,21 +44,27 @@ static bool is_block_job(Job *job)
> > >               job_type(job) == JOB_TYPE_STREAM;
> > >    }
> > >    -BlockJob *block_job_next(BlockJob *bjob)
> > > +BlockJob *block_job_next_locked(BlockJob *bjob)
> > >    {
> > >        Job *job = bjob ? &bjob->job : NULL;
> > >        GLOBAL_STATE_CODE();
> > >          do {
> > > -        job = job_next(job);
> > > +        job = job_next_locked(job);
> > >        } while (job && !is_block_job(job));
> > >          return job ? container_of(job, BlockJob, job) : NULL;
> > >    }
> > >    -BlockJob *block_job_get(const char *id)
> > > +BlockJob *block_job_next(BlockJob *bjob)
> > >    {
> > > -    Job *job = job_get(id);
> > > +    JOB_LOCK_GUARD();
> > > +    return block_job_next_locked(bjob);
> > > +}
> > > +
> > > +BlockJob *block_job_get_locked(const char *id)
> > > +{
> > > +    Job *job = job_get_locked(id);
> > >        GLOBAL_STATE_CODE();
> > >          if (job && is_block_job(job)) {
> > > @@ -68,6 +74,12 @@ BlockJob *block_job_get(const char *id)
> > >        }
> > >    }
> > >    +BlockJob *block_job_get(const char *id)
> > > +{
> > > +    JOB_LOCK_GUARD();
> > > +    return block_job_get_locked(id);
> > > +}
> > > +
> > >    void block_job_free(Job *job)
> > >    {
> > >        BlockJob *bjob = container_of(job, BlockJob, job);
> > > @@ -256,14 +268,14 @@ static bool job_timer_pending(Job *job)
> > >        return timer_pending(&job->sleep_timer);
> > >    }
> > >    -bool block_job_set_speed(BlockJob *job, int64_t speed, Error **errp)
> > > +bool block_job_set_speed_locked(BlockJob *job, int64_t speed, Error
> > > **errp)
> > >    {
> > >        const BlockJobDriver *drv = block_job_driver(job);
> > >        int64_t old_speed = job->speed;
> > >          GLOBAL_STATE_CODE();
> > >    -    if (job_apply_verb(&job->job, JOB_VERB_SET_SPEED, errp) < 0) {
> > > +    if (job_apply_verb_locked(&job->job, JOB_VERB_SET_SPEED, errp) <
> > > 0) {
> > >            return false;
> > >        }
> > >        if (speed < 0) {
> > > @@ -277,7 +289,9 @@ bool block_job_set_speed(BlockJob *job, int64_t
> > > speed, Error **errp)
> > >        job->speed = speed;
> > >          if (drv->set_speed) {
> > > +        job_unlock();
> > >            drv->set_speed(job, speed);
> > > +        job_lock();
> > >        }
> > >          if (speed && speed <= old_speed) {
> > > @@ -285,18 +299,24 @@ bool block_job_set_speed(BlockJob *job, int64_t
> > > speed, Error **errp)
> > >        }
> > >          /* kick only if a timer is pending */
> > > -    job_enter_cond(&job->job, job_timer_pending);
> > > +    job_enter_cond_locked(&job->job, job_timer_pending);
> > >          return true;
> > >    }
> > >    +bool block_job_set_speed(BlockJob *job, int64_t speed, Error **errp)
> > > +{
> > > +    JOB_LOCK_GUARD();
> > > +    return block_job_set_speed_locked(job, speed, errp);
> > > +}
> > > +
> > >    int64_t block_job_ratelimit_get_delay(BlockJob *job, uint64_t n)
> > >    {
> > >        IO_CODE();
> > >        return ratelimit_calculate_delay(&job->limit, n);
> > >    }
> > >    -BlockJobInfo *block_job_query(BlockJob *job, Error **errp)
> > > +BlockJobInfo *block_job_query_locked(BlockJob *job, Error **errp)
> > >    {
> > >        BlockJobInfo *info;
> > >        uint64_t progress_current, progress_total;
> > > @@ -320,7 +340,7 @@ BlockJobInfo *block_job_query(BlockJob *job, Error
> > > **errp)
> > >        info->len       = progress_total;
> > >        info->speed     = job->speed;
> > >        info->io_status = job->iostatus;
> > > -    info->ready     = job_is_ready(&job->job),
> > > +    info->ready     = job_is_ready_locked(&job->job),
> > >        info->status    = job->job.status;
> > >        info->auto_finalize = job->job.auto_finalize;
> > >        info->auto_dismiss  = job->job.auto_dismiss;
> > > @@ -333,6 +353,12 @@ BlockJobInfo *block_job_query(BlockJob *job,
> > > Error **errp)
> > >        return info;
> > >    }
> > >    +BlockJobInfo *block_job_query(BlockJob *job, Error **errp)
> > > +{
> > > +    JOB_LOCK_GUARD();
> > > +    return block_job_query_locked(job, errp);
> > > +}
> > > +
> > >    static void block_job_iostatus_set_err(BlockJob *job, int error)
> > >    {
> > >        if (job->iostatus == BLOCK_DEVICE_IO_STATUS_OK) {
> > > @@ -478,7 +504,7 @@ fail:
> > >        return NULL;
> > >    }
> > >    -void block_job_iostatus_reset(BlockJob *job)
> > > +void block_job_iostatus_reset_locked(BlockJob *job)
> > >    {
> > >        GLOBAL_STATE_CODE();
> > >        if (job->iostatus == BLOCK_DEVICE_IO_STATUS_OK) {
> > > @@ -488,6 +514,12 @@ void block_job_iostatus_reset(BlockJob *job)
> > >        job->iostatus = BLOCK_DEVICE_IO_STATUS_OK;
> > >    }
> > >    +void block_job_iostatus_reset(BlockJob *job)
> > > +{
> > > +    JOB_LOCK_GUARD();
> > > +    block_job_iostatus_reset_locked(job);
> > > +}
> > > +
> > >    void block_job_user_resume(Job *job)
> > >    {
> > >        BlockJob *bjob = container_of(job, BlockJob, job);
> > > diff --git a/include/block/blockjob.h b/include/block/blockjob.h
> > > index 6525e16fd5..3959a98612 100644
> > > --- a/include/block/blockjob.h
> > > +++ b/include/block/blockjob.h
> > > @@ -92,6 +92,9 @@ typedef struct BlockJob {
> > >     */
> > >    BlockJob *block_job_next(BlockJob *job);
> > >    +/* Same as block_job_next(), but called with job lock held. */
> > > +BlockJob *block_job_next_locked(BlockJob *job);
> > > +
> > >    /**
> > >     * block_job_get:
> > >     * @id: The id of the block job.
> > > @@ -102,6 +105,9 @@ BlockJob *block_job_next(BlockJob *job);
> > >     */
> > >    BlockJob *block_job_get(const char *id);
> > >    +/* Same as block_job_get(), but called with job lock held. */
> > > +BlockJob *block_job_get_locked(const char *id);
> > > +
> > >    /**
> > >     * block_job_add_bdrv:
> > >     * @job: A block job
> > > @@ -145,6 +151,9 @@ bool block_job_has_bdrv(BlockJob *job,
> > > BlockDriverState *bs);
> > >     */
> > >    bool block_job_set_speed(BlockJob *job, int64_t speed, Error **errp);
> > >    +/* Same as block_job_set_speed(), but called with job lock held. */
> > > +bool block_job_set_speed_locked(BlockJob *job, int64_t speed, Error
> > > **errp);
> > > +
> > >    /**
> > >     * block_job_query:
> > >     * @job: The job to get information about.
> > > @@ -153,6 +162,9 @@ bool block_job_set_speed(BlockJob *job, int64_t
> > > speed, Error **errp);
> > >     */
> > >    BlockJobInfo *block_job_query(BlockJob *job, Error **errp);
> > >    +/* Same as block_job_query(), but called with job lock held. */
> > > +BlockJobInfo *block_job_query_locked(BlockJob *job, Error **errp);
> > > +
> > >    /**
> > >     * block_job_iostatus_reset:
> > >     * @job: The job whose I/O status should be reset.
> > > @@ -162,6 +174,9 @@ BlockJobInfo *block_job_query(BlockJob *job, Error
> > > **errp);
> > >     */
> > >    void block_job_iostatus_reset(BlockJob *job);
> > >    +/* Same as block_job_iostatus_reset(), but called with job lock
> > > held. */
> > > +void block_job_iostatus_reset_locked(BlockJob *job);
> > > +
> > >    /*
> > >     * block_job_get_aio_context:
> > >     *


--
Best regards,
Vladimir