Messages in this thread | | | From | Mike Snitzer <> | Date | Thu, 17 Feb 2011 22:19:52 -0500 | Subject | Re: blk_throtl_exit taking q->queue_lock is problematic |
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On Thu, Feb 17, 2011 at 9:40 PM, NeilBrown <neilb@suse.de> wrote: > On Thu, 17 Feb 2011 11:59:06 -0500 Vivek Goyal <vgoyal@redhat.com> wrote: >> So if we do this change for performance reasons, it still makes sense >> but doing this change because md provided a q->queue_lock and took away that >> lock without notifying block layer hence we do this change, is still not >> the right reason, IMHO. > > Well...I like that patch, as it makes my life easier.... > > But I agree that md is doing something wrong. Now that ->queue_lock is > always initialised, it is wrong to leave it in a state where it not defined. > > So maybe I'll apply this (after testing it a bit. The only reason for taking > the lock queue_lock in a couple of places is to silence some warnings. > > Thanks, > NeilBrown > > > diff --git a/drivers/md/raid1.c b/drivers/md/raid1.c > index a23ffa3..909282d 100644 > --- a/drivers/md/raid1.c > +++ b/drivers/md/raid1.c > @@ -959,7 +961,9 @@ static int make_request(mddev_t *mddev, struct bio * bio) > atomic_inc(&r1_bio->remaining); > spin_lock_irqsave(&conf->device_lock, flags); > bio_list_add(&conf->pending_bio_list, mbio); > + spin_lock(mddev->queue->queue_lock); > blk_plug_device(mddev->queue); > + spin_unlock(mddev->queue->queue_lock); > spin_unlock_irqrestore(&conf->device_lock, flags); > } > r1_bio_write_done(r1_bio, bio->bi_vcnt, behind_pages, behind_pages != NULL);
Noticed an inconsistency, raid10.c's additional locking also protects the bio_list_add() whereas raid1.c's doesn't. Seems the additional protection in raid10 isn't needed?
> diff --git a/drivers/md/raid10.c b/drivers/md/raid10.c > index 3b607b2..60e6cb1 100644 > --- a/drivers/md/raid10.c > +++ b/drivers/md/raid10.c > @@ -970,8 +972,10 @@ static int make_request(mddev_t *mddev, struct bio * bio) > > atomic_inc(&r10_bio->remaining); > spin_lock_irqsave(&conf->device_lock, flags); > + spin_lock(mddev->queue->queue_lock); > bio_list_add(&conf->pending_bio_list, mbio); > blk_plug_device(mddev->queue); > + spin_unlock(mddev->queue->queue_lock); > spin_unlock_irqrestore(&conf->device_lock, flags); > } > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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