From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Paul E. McKenney" 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 Message-ID: <1507594969-8347-3-git-send-email-paulmck@linux.vnet.ibm.com> References: <20171010001951.GA6476@linux.vnet.ibm.com> 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 , , To: linux-kernel@vger.kernel.org Return-path: In-Reply-To: <20171010001951.GA6476@linux.vnet.ibm.com> Sender: linux-kernel-owner@vger.kernel.org List-Id: netdev.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