From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754438AbaIXRU7 (ORCPT ); Wed, 24 Sep 2014 13:20:59 -0400 Received: from mail-vc0-f171.google.com ([209.85.220.171]:42868 "EHLO mail-vc0-f171.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753917AbaIXRUz (ORCPT ); Wed, 24 Sep 2014 13:20:55 -0400 Date: Wed, 24 Sep 2014 13:20:51 -0400 From: Tejun Heo To: Jens Axboe Cc: Christoph Hellwig , linux-kernel@vger.kernel.org, linux-scsi@vger.kernel.org, Kent Overstreet Subject: [PATCH percpu/for-3.18] Revert "blk-mq, percpu_ref: implement a kludge for SCSI blk-mq stall during probe" Message-ID: <20140924172051.GA29067@mtj.dyndns.org> References: <20140923055924.GA10295@lst.de> <20140923060141.GF11740@mtj.dyndns.org> <20140923060906.GA10547@lst.de> <20140923061152.GI11740@mtj.dyndns.org> <5421968B.7080309@kernel.dk> <20140923192432.GA24441@mtj.dyndns.org> <20140924082348.GB8894@lst.de> <5422D589.5070009@kernel.dk> <20140924143320.GG16555@htj.dyndns.org> <5422D656.7020006@kernel.dk> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <5422D656.7020006@kernel.dk> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org >>From 9eca80461a45177e456219a9cd944c27675d6512 Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Wed, 24 Sep 2014 13:07:33 -0400 This reverts commit 0a30288da1aec914e158c2d7a3482a85f632750f, which was a temporary fix for SCSI blk-mq stall issue. The following patches will fix the issue properly by introducing atomic mode to percpu_ref. Signed-off-by: Tejun Heo Cc: Kent Overstreet Cc: Jens Axboe Cc: Christoph Hellwig --- Hello, I pulled in block/for-linus into percpu/for-3.18 and reverted the temp fix. Will apply the patchset to implement the proper fix on top of it. Thanks. block/blk-mq.c | 11 +---------- include/linux/percpu-refcount.h | 1 - lib/percpu-refcount.c | 16 ---------------- 3 files changed, 1 insertion(+), 27 deletions(-) diff --git a/block/blk-mq.c b/block/blk-mq.c index 255d79c..44a78ae 100644 --- a/block/blk-mq.c +++ b/block/blk-mq.c @@ -119,16 +119,7 @@ void blk_mq_freeze_queue(struct request_queue *q) spin_unlock_irq(q->queue_lock); if (freeze) { - /* - * XXX: Temporary kludge to work around SCSI blk-mq stall. - * SCSI synchronously creates and destroys many queues - * back-to-back during probe leading to lengthy stalls. - * This will be fixed by keeping ->mq_usage_counter in - * atomic mode until genhd registration, but, for now, - * let's work around using expedited synchronization. - */ - __percpu_ref_kill_expedited(&q->mq_usage_counter); - + percpu_ref_kill(&q->mq_usage_counter); blk_mq_run_queues(q, false); } wait_event(q->mq_freeze_wq, percpu_ref_is_zero(&q->mq_usage_counter)); diff --git a/include/linux/percpu-refcount.h b/include/linux/percpu-refcount.h index 11b38ce..5df6784 100644 --- a/include/linux/percpu-refcount.h +++ b/include/linux/percpu-refcount.h @@ -72,7 +72,6 @@ void percpu_ref_reinit(struct percpu_ref *ref); void percpu_ref_exit(struct percpu_ref *ref); void percpu_ref_kill_and_confirm(struct percpu_ref *ref, percpu_ref_func_t *confirm_kill); -void __percpu_ref_kill_expedited(struct percpu_ref *ref); /** * percpu_ref_kill - drop the initial ref diff --git a/lib/percpu-refcount.c b/lib/percpu-refcount.c index c6c31e2..559ee0b 100644 --- a/lib/percpu-refcount.c +++ b/lib/percpu-refcount.c @@ -189,19 +189,3 @@ void percpu_ref_kill_and_confirm(struct percpu_ref *ref, call_rcu_sched(&ref->rcu, percpu_ref_kill_rcu); } EXPORT_SYMBOL_GPL(percpu_ref_kill_and_confirm); - -/* - * XXX: Temporary kludge to work around SCSI blk-mq stall. Used only by - * block/blk-mq.c::blk_mq_freeze_queue(). Will be removed during v3.18 - * devel cycle. Do not use anywhere else. - */ -void __percpu_ref_kill_expedited(struct percpu_ref *ref) -{ - WARN_ONCE(ref->pcpu_count_ptr & PCPU_REF_DEAD, - "percpu_ref_kill() called more than once on %pf!", - ref->release); - - ref->pcpu_count_ptr |= PCPU_REF_DEAD; - synchronize_sched_expedited(); - percpu_ref_kill_rcu(&ref->rcu); -} -- 1.9.3