From: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> 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" <paulmck@linux.vnet.ibm.com>, Ariel Elior <Ariel.Elior@cavium.com>, <everest-linux-l2@cavium.com>, <netdev@vger.kernel.org> 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 [thread overview] Message-ID: <1507594969-8347-3-git-send-email-paulmck@linux.vnet.ibm.com> (raw) In-Reply-To: <20171010001951.GA6476@linux.vnet.ibm.com> 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 <paulmck@linux.vnet.ibm.com> Cc: Ariel Elior <Ariel.Elior@cavium.com> Cc: <everest-linux-l2@cavium.com> Cc: <netdev@vger.kernel.org> --- 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
WARNING: multiple messages have this Message-ID (diff)
From: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> 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" <paulmck@linux.vnet.ibm.com>, Ariel Elior <Ariel.Elior@cavium.com>, everest-linux-l2@cavium.com, netdev@vger.kernel.org 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 [thread overview] Message-ID: <1507594969-8347-3-git-send-email-paulmck@linux.vnet.ibm.com> (raw) In-Reply-To: <20171010001951.GA6476@linux.vnet.ibm.com> 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 <paulmck@linux.vnet.ibm.com> Cc: Ariel Elior <Ariel.Elior@cavium.com> Cc: <everest-linux-l2@cavium.com> Cc: <netdev@vger.kernel.org> --- 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
next prev parent reply other threads:[~2017-10-10 0:23 UTC|newest] Thread overview: 70+ messages / expand[flat|nested] mbox.gz Atom feed top 2017-10-10 0:19 [PATCH RFC tip/core/rcu 0/15] Remove to-be-unneeded smp_read_barrier_depends() Paul E. McKenney 2017-10-10 0:22 ` [PATCH RFC tip/core/rcu 01/15] doc: READ_ONCE() now implies smp_barrier_depends() Paul E. McKenney 2017-10-10 0:22 ` [PATCH RFC tip/core/rcu 02/15] mn10300: READ_ONCE() now implies smp_read_barrier_depends() Paul E. McKenney 2017-10-10 0:22 ` Paul E. McKenney 2017-10-10 0:22 ` Paul E. McKenney [this message] 2017-10-10 0:22 ` [PATCH RFC tip/core/rcu 03/15] drivers/net/ethernet/qlogic/qed: Fix __qed_spq_block() ordering Paul E. McKenney 2017-10-10 0:22 ` [PATCH RFC tip/core/rcu 04/15] fs/dcache: Use release-acquire for name/length update Paul E. McKenney 2017-10-10 0:22 ` Paul E. McKenney 2017-10-10 0:22 ` [PATCH RFC tip/core/rcu 05/15] percpu: READ_ONCE() now implies smp_read_barrier_depends() Paul E. McKenney 2017-10-10 14:08 ` Tejun Heo 2017-10-10 15:30 ` Paul E. McKenney 2017-10-10 15:49 ` Tejun Heo 2017-10-10 0:22 ` [PATCH RFC tip/core/rcu 06/15] rcu: Adjust read-side accessor comments for READ_ONCE() Paul E. McKenney 2017-10-10 0:22 ` [PATCH RFC tip/core/rcu 07/15] rtnetlink: Update now-misleading smp_read_barrier_depends() comment Paul E. McKenney 2017-10-10 0:22 ` [PATCH RFC tip/core/rcu 08/15] seqlock: Remove now-redundant smp_read_barrier_depends() Paul E. McKenney 2017-10-10 0:22 ` [PATCH RFC tip/core/rcu 09/15] uprobes: " Paul E. McKenney 2017-10-10 0:22 ` [PATCH RFC tip/core/rcu 10/15] locking: Remove smp_read_barrier_depends() from queued_spin_lock_slowpath() Paul E. McKenney 2017-10-10 0:22 ` [PATCH RFC tip/core/rcu 11/15] tracepoint: Remove smp_read_barrier_depends() from comment Paul E. McKenney 2017-10-10 0:31 ` Steven Rostedt 2017-10-10 1:12 ` Mathieu Desnoyers 2017-10-10 15:32 ` Paul E. McKenney 2017-10-10 0:22 ` [PATCH RFC tip/core/rcu 12/15] lib/assoc_array: Remove smp_read_barrier_depends() Paul E. McKenney 2017-10-10 8:39 ` Peter Zijlstra 2017-10-10 9:36 ` David Howells 2017-10-10 0:22 ` [PATCH RFC tip/core/rcu 13/15] mm/ksm: Remove now-redundant smp_read_barrier_depends() Paul E. McKenney 2017-10-10 0:22 ` Paul E. McKenney 2017-10-10 0:22 ` Paul E. McKenney 2017-10-10 0:22 ` [PATCH RFC tip/core/rcu 14/15] netfilter: " Paul E. McKenney 2017-10-10 0:22 ` Paul E. McKenney 2017-10-10 8:43 ` Peter Zijlstra 2017-10-10 15:56 ` Paul E. McKenney 2017-10-10 0:22 ` [PATCH RFC tip/core/rcu 15/15] keyring: " Paul E. McKenney 2017-10-10 0:22 ` Paul E. McKenney 2017-10-10 0:22 ` Paul E. McKenney 2017-10-10 0:22 ` Paul E. McKenney 2017-10-10 9:35 ` [PATCH RFC tip/core/rcu 12/15] lib/assoc_array: Remove smp_read_barrier_depends() David Howells 2017-10-10 15:50 ` Paul E. McKenney 2017-10-10 15:54 ` Peter Zijlstra 2017-10-10 16:05 ` Paul E. McKenney 2017-10-11 12:19 ` David Howells 2017-10-11 12:22 ` Will Deacon 2017-10-11 12:54 ` Paul E. McKenney 2017-10-11 14:18 ` Will Deacon 2017-10-11 14:50 ` Paul E. McKenney 2017-10-11 12:58 ` Paul E. McKenney 2017-10-11 15:17 ` David Howells 2017-10-11 15:59 ` Paul E. McKenney 2017-10-11 16:12 ` Peter Zijlstra 2017-10-11 16:24 ` Peter Zijlstra 2017-10-11 16:47 ` Paul E. McKenney 2017-10-11 16:54 ` Peter Zijlstra 2017-10-11 17:06 ` Paul E. McKenney 2017-10-11 17:11 ` Peter Zijlstra 2017-10-11 17:34 ` Paul E. McKenney 2017-10-11 18:43 ` Dmitry Vyukov 2017-10-11 18:56 ` Linus Torvalds 2017-10-11 19:28 ` Paul E. McKenney 2017-10-11 19:59 ` Dmitry Vyukov 2017-10-11 17:14 ` Paul E. McKenney 2017-10-11 17:19 ` Mark Rutland 2017-10-11 16:50 ` Paul E. McKenney 2017-10-11 16:07 ` David Howells 2017-10-11 16:17 ` Peter Zijlstra 2017-10-11 16:19 ` Paul E. McKenney 2017-10-11 15:28 ` David Howells 2017-10-11 16:02 ` Paul E. McKenney 2017-10-10 9:59 ` David Howells 2017-10-10 15:52 ` Paul E. McKenney 2017-10-11 12:21 ` [PATCH RFC tip/core/rcu 0/15] Remove to-be-unneeded smp_read_barrier_depends() David Howells 2017-10-11 12:56 ` Paul E. McKenney
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