From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755886AbdJJAXC (ORCPT ); Mon, 9 Oct 2017 20:23:02 -0400 Received: from mx0a-001b2d01.pphosted.com ([148.163.156.1]:49402 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755720AbdJJAWy (ORCPT ); Mon, 9 Oct 2017 20:22:54 -0400 From: "Paul E. McKenney" To: linux-kernel@vger.kernel.org Cc: mingo@kernel.org, torvalds@linux-foundation.org, mark.rutland@arm.com, dhowells@redhat.com, linux-arch@vger.kernel.org, peterz@infradead.org, will.deacon@arm.com, "Paul E. McKenney" , Ariel Elior , , Subject: [PATCH RFC tip/core/rcu 03/15] drivers/net/ethernet/qlogic/qed: Fix __qed_spq_block() ordering Date: Mon, 9 Oct 2017 17:22:37 -0700 X-Mailer: git-send-email 2.5.2 In-Reply-To: <20171010001951.GA6476@linux.vnet.ibm.com> References: <20171010001951.GA6476@linux.vnet.ibm.com> X-TM-AS-GCONF: 00 x-cbid: 17101000-0008-0000-0000-0000028E2D69 X-IBM-SpamModules-Scores: X-IBM-SpamModules-Versions: BY=3.00007870; HX=3.00000241; KW=3.00000007; PH=3.00000004; SC=3.00000235; SDB=6.00928858; UDB=6.00467488; IPR=6.00709129; BA=6.00005631; NDR=6.00000001; ZLA=6.00000005; ZF=6.00000009; ZB=6.00000000; ZP=6.00000000; ZH=6.00000000; ZU=6.00000002; MB=3.00017467; XFM=3.00000015; UTC=2017-10-10 00:22:52 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 17101000-0009-0000-0000-000036F4C872 Message-Id: <1507594969-8347-3-git-send-email-paulmck@linux.vnet.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:,, definitions=2017-10-09_07:,, signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 spamscore=0 suspectscore=1 malwarescore=0 phishscore=0 adultscore=0 bulkscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1707230000 definitions=main-1710100003 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The __qed_spq_block() function expects an smp_read_barrier_depends() to order a prior READ_ONCE() against a later load that does not depend on the prior READ_ONCE(), an expectation that can fail to be met. This commit therefore replaces the READ_ONCE() with smp_load_acquire() and removes the smp_read_barrier_depends(). Signed-off-by: Paul E. McKenney Cc: Ariel Elior Cc: Cc: --- drivers/net/ethernet/qlogic/qed/qed_spq.c | 4 +--- 1 file changed, 1 insertion(+), 3 deletions(-) diff --git a/drivers/net/ethernet/qlogic/qed/qed_spq.c b/drivers/net/ethernet/qlogic/qed/qed_spq.c index be48d9abd001..c1237ec58b6c 100644 --- a/drivers/net/ethernet/qlogic/qed/qed_spq.c +++ b/drivers/net/ethernet/qlogic/qed/qed_spq.c @@ -97,9 +97,7 @@ static int __qed_spq_block(struct qed_hwfn *p_hwfn, while (iter_cnt--) { /* Validate we receive completion update */ - if (READ_ONCE(comp_done->done) == 1) { - /* Read updated FW return value */ - smp_read_barrier_depends(); + if (smp_load_acquire(&comp_done->done) == 1) { /* ^^^ */ if (p_fw_ret) *p_fw_ret = comp_done->fw_return_code; return 0; -- 2.5.2