| Message ID | 20190401044247.29881-3-ming.lei@redhat.com (mailing list archive) |
|---|---|
| State | Superseded |
| Headers | show |
| Series | blk-mq: allow to run queue if queue refcount is held | expand |
On Mon, 2019-04-01 at 12:42 +0800, Ming Lei wrote: > Now freeing hw queue resource is moved to hctx's release handler, > we don't need to worry about the race between blk_cleanup_queue and > run queue any more. > > So don't drain in-progress dispatch in blk_cleanup_queue(). > > This is basically revert of c2856ae2f315 ("blk-mq: quiesce queue before > freeing queue"). > > Cc: Dongli Zhang <dongli.zhang@oracle.com> > Cc: James Smart <james.smart@broadcom.com> > Cc: Bart Van Assche <bart.vanassche@wdc.com> > Cc: linux-scsi@vger.kernel.org, > Cc: Martin K . Petersen <martin.petersen@oracle.com>, > Cc: Christoph Hellwig <hch@lst.de>, > Cc: James E . J . Bottomley <jejb@linux.vnet.ibm.com>, > Cc: jianchao wang <jianchao.w.wang@oracle.com> > Signed-off-by: Ming Lei <ming.lei@redhat.com> > --- > block/blk-core.c | 12 ------------ > 1 file changed, 12 deletions(-) > > diff --git a/block/blk-core.c b/block/blk-core.c > index b3bbf8a5110d..491dc0295778 100644 > --- a/block/blk-core.c > +++ b/block/blk-core.c > @@ -347,18 +347,6 @@ void blk_cleanup_queue(struct request_queue *q) > > blk_queue_flag_set(QUEUE_FLAG_DEAD, q); > > - /* > - * make sure all in-progress dispatch are completed because > - * blk_freeze_queue() can only complete all requests, and > - * dispatch may still be in-progress since we dispatch requests > - * from more than one contexts. > - * > - * We rely on driver to deal with the race in case that queue > - * initialization isn't done. > - */ > - if (queue_is_mq(q) && blk_queue_init_done(q)) > - blk_mq_quiesce_queue(q); > - > /* for synchronous bio-based driver finish in-flight integrity i/o */ > blk_flush_integrity(); Many block drivers clean up resources immediately after blk_cleanup_queue() returns. Not waiting for ongoing .queue_rq() calls to finish is wrong because it can cause block drivers to destroy resources that are in use by a concurrent .queue_rq() call. Bart.
On Mon, Apr 01, 2019 at 08:14:59AM -0700, Bart Van Assche wrote: > On Mon, 2019-04-01 at 12:42 +0800, Ming Lei wrote: > > Now freeing hw queue resource is moved to hctx's release handler, > > we don't need to worry about the race between blk_cleanup_queue and > > run queue any more. > > > > So don't drain in-progress dispatch in blk_cleanup_queue(). > > > > This is basically revert of c2856ae2f315 ("blk-mq: quiesce queue before > > freeing queue"). > > > > Cc: Dongli Zhang <dongli.zhang@oracle.com> > > Cc: James Smart <james.smart@broadcom.com> > > Cc: Bart Van Assche <bart.vanassche@wdc.com> > > Cc: linux-scsi@vger.kernel.org, > > Cc: Martin K . Petersen <martin.petersen@oracle.com>, > > Cc: Christoph Hellwig <hch@lst.de>, > > Cc: James E . J . Bottomley <jejb@linux.vnet.ibm.com>, > > Cc: jianchao wang <jianchao.w.wang@oracle.com> > > Signed-off-by: Ming Lei <ming.lei@redhat.com> > > --- > > block/blk-core.c | 12 ------------ > > 1 file changed, 12 deletions(-) > > > > diff --git a/block/blk-core.c b/block/blk-core.c > > index b3bbf8a5110d..491dc0295778 100644 > > --- a/block/blk-core.c > > +++ b/block/blk-core.c > > @@ -347,18 +347,6 @@ void blk_cleanup_queue(struct request_queue *q) > > > > blk_queue_flag_set(QUEUE_FLAG_DEAD, q); > > > > - /* > > - * make sure all in-progress dispatch are completed because > > - * blk_freeze_queue() can only complete all requests, and > > - * dispatch may still be in-progress since we dispatch requests > > - * from more than one contexts. > > - * > > - * We rely on driver to deal with the race in case that queue > > - * initialization isn't done. > > - */ > > - if (queue_is_mq(q) && blk_queue_init_done(q)) > > - blk_mq_quiesce_queue(q); > > - > > /* for synchronous bio-based driver finish in-flight integrity i/o */ > > blk_flush_integrity(); > > Many block drivers clean up resources immediately after blk_cleanup_queue() > returns. Not waiting for ongoing .queue_rq() calls to finish is wrong because > it can cause block drivers to destroy resources that are in use by a concurrent > .queue_rq() call. blk_freeze_queue() has returned, so there can't be any in-flight IOs and .queue_rq(), but there might be run queue activities, which do not call into driver. Thanks, Ming
diff --git a/block/blk-core.c b/block/blk-core.c index b3bbf8a5110d..491dc0295778 100644 --- a/block/blk-core.c +++ b/block/blk-core.c @@ -347,18 +347,6 @@ void blk_cleanup_queue(struct request_queue *q) blk_queue_flag_set(QUEUE_FLAG_DEAD, q); - /* - * make sure all in-progress dispatch are completed because - * blk_freeze_queue() can only complete all requests, and - * dispatch may still be in-progress since we dispatch requests - * from more than one contexts. - * - * We rely on driver to deal with the race in case that queue - * initialization isn't done. - */ - if (queue_is_mq(q) && blk_queue_init_done(q)) - blk_mq_quiesce_queue(q); - /* for synchronous bio-based driver finish in-flight integrity i/o */ blk_flush_integrity();
Now freeing hw queue resource is moved to hctx's release handler, we don't need to worry about the race between blk_cleanup_queue and run queue any more. So don't drain in-progress dispatch in blk_cleanup_queue(). This is basically revert of c2856ae2f315 ("blk-mq: quiesce queue before freeing queue"). Cc: Dongli Zhang <dongli.zhang@oracle.com> Cc: James Smart <james.smart@broadcom.com> Cc: Bart Van Assche <bart.vanassche@wdc.com> Cc: linux-scsi@vger.kernel.org, Cc: Martin K . Petersen <martin.petersen@oracle.com>, Cc: Christoph Hellwig <hch@lst.de>, Cc: James E . J . Bottomley <jejb@linux.vnet.ibm.com>, Cc: jianchao wang <jianchao.w.wang@oracle.com> Signed-off-by: Ming Lei <ming.lei@redhat.com> --- block/blk-core.c | 12 ------------ 1 file changed, 12 deletions(-)