Messages in this thread | | | Date | Wed, 24 Jul 2002 16:46:30 +0200 | From | Marcin Dalecki <> | Subject | Re: cpqarray broken since 2.5.19 |
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Bartlomiej Zolnierkiewicz wrote: > On Wed, 24 Jul 2002, Jens Axboe wrote: > > >>On Wed, Jul 24 2002, Marcin Dalecki wrote: >> >>>>Jens, the same is in cciss.c. >>>>Please remove locking from blk_stop_queue() (as you suggested) or intrduce >>>>unlocking in request_functions. >>>> >>> >>>Bartek I think the removal is just for reassertion that the >>>locking is the problem. You can't remove it easly from >>>blk_stop_queue() unless you make it mandatory that blk_stop_queue >>>has to be run with the lock already held. Or in other words >>>basically -> Don't use blk_stop_queue() outside of ->request_fn. >> >>Of couse Bart is advocating just making sure that every caller of >>blk_stop_queue() _has_ the queue_lock before calling it, not removing >>the locking there. >> >>-- >>Jens Axboe > > > And I'm also advocating for __blk_start_queue() ideal for usage in > ata_end_request(). And moving spin_lock scope to cover test_and_set_bit() > in blk_start_queue() (for coherency and avoiding spurious calls to > q->request_fn() )
You mean this:
void blk_start_queue(request_queue_t *q) { if (test_bit(QUEUE_FLAG_STOPPED, &q->queue_flags)) { unsigned long flags;
spin_lock_irqsave(q->queue_lock, flags); if (!test_bit(QUEUE_FLAG_STOPPED, &q->queue_flags)) { spin_unlock_irqrestore(q->queue_lock, flags); return; } clear_bit(QUEUE_FLAG_STOPPED, &q->queue_flags); if (!elv_queue_empty(q)) q->request_fn(q); spin_unlock_irqrestore(q->queue_lock, flags); } }
Becouse this is avoiding checking for spinlock in the case the queue is not stopped.
The spinlock free variant isn't needed right.
> However IDE_BUSY -> QUEUE_STOPPED_FLAG is braindamaged idea.
You should never see it. Think of it as a mind bridge between IDE_BUSY and queue plug and unplug please. Becouse the purpose of IDE_BUSY *is* to effectively stall queue processing for the time of internally issued request. OK?
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