From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753112AbdLGQYH (ORCPT ); Thu, 7 Dec 2017 11:24:07 -0500 Received: from omzsmtpe01.verizonbusiness.com ([199.249.25.210]:19368 "EHLO omzsmtpe01.verizonbusiness.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932814AbdLGP4s (ORCPT ); Thu, 7 Dec 2017 10:56:48 -0500 From: alexander.levin@verizon.com Cc: Mike Christie , Nicholas Bellinger , alexander.levin@verizon.com X-Host: surveyor.tdc.vzwcorp.com To: "linux-kernel@vger.kernel.org" , "stable@vger.kernel.org" Subject: [PATCH AUTOSEL for 3.18 26/59] target: Use system workqueue for ALUA transitions Thread-Topic: [PATCH AUTOSEL for 3.18 26/59] target: Use system workqueue for ALUA transitions Thread-Index: AQHTb3M+It7dBnPC2EqdZF9W6GwWbw== Date: Thu, 7 Dec 2017 15:51:29 +0000 Message-ID: <20171207155116.6013-26-alexander.levin@verizon.com> References: <20171207155116.6013-1-alexander.levin@verizon.com> In-Reply-To: <20171207155116.6013-1-alexander.levin@verizon.com> Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-ms-exchange-messagesentrepresentingtype: 1 x-ms-exchange-transport-fromentityheader: Hosted x-originating-ip: [10.144.60.250] Content-Type: text/plain; charset="iso-8859-1" MIME-Version: 1.0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: 8bit X-MIME-Autoconverted: from quoted-printable to 8bit by nfs id vB7GOCpf006321 From: Mike Christie [ Upstream commit 207ee84133c00a8a2a5bdec94df4a5b37d78881c ] If tcmu-runner is processing a STPG and needs to change the kernel's ALUA state then we cannot use the same work queue for task management requests and ALUA transitions, because we could deadlock. The problem occurs when a STPG times out before tcmu-runner is able to call into target_tg_pt_gp_alua_access_state_store-> core_alua_do_port_transition -> core_alua_do_transition_tg_pt -> queue_work. In this case, the tmr is on the work queue waiting for the STPG to complete, but the STPG transition is now queued behind the waiting tmr. Note: This bug will also be fixed by this patch: http://www.spinics.net/lists/target-devel/msg14560.html which switches the tmr code to use the system workqueues. For both, I am not sure if we need a dedicated workqueue since it is not a performance path and I do not think we need WQ_MEM_RECLAIM to make forward progress to free up memory like the block layer does. Signed-off-by: Mike Christie Signed-off-by: Nicholas Bellinger Signed-off-by: Sasha Levin --- drivers/target/target_core_alua.c | 8 +++----- 1 file changed, 3 insertions(+), 5 deletions(-) diff --git a/drivers/target/target_core_alua.c b/drivers/target/target_core_alua.c index fb87780929d2..701f94ae5eef 100644 --- a/drivers/target/target_core_alua.c +++ b/drivers/target/target_core_alua.c @@ -1126,13 +1126,11 @@ static int core_alua_do_transition_tg_pt( unsigned long transition_tmo; transition_tmo = tg_pt_gp->tg_pt_gp_implicit_trans_secs * HZ; - queue_delayed_work(tg_pt_gp->tg_pt_gp_dev->tmr_wq, - &tg_pt_gp->tg_pt_gp_transition_work, - transition_tmo); + schedule_delayed_work(&tg_pt_gp->tg_pt_gp_transition_work, + transition_tmo); } else { tg_pt_gp->tg_pt_gp_transition_complete = &wait; - queue_delayed_work(tg_pt_gp->tg_pt_gp_dev->tmr_wq, - &tg_pt_gp->tg_pt_gp_transition_work, 0); + schedule_delayed_work(&tg_pt_gp->tg_pt_gp_transition_work, 0); wait_for_completion(&wait); tg_pt_gp->tg_pt_gp_transition_complete = NULL; } -- 2.11.0