Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752331AbdFAQUK (ORCPT ); Thu, 1 Jun 2017 12:20:10 -0400 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:33416 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752088AbdFAPoy (ORCPT ); Thu, 1 Jun 2017 11:44:54 -0400 Content-Type: text/plain; charset="UTF-8" Content-Disposition: inline Content-Transfer-Encoding: 8bit MIME-Version: 1.0 From: Ben Hutchings To: linux-kernel@vger.kernel.org, stable@vger.kernel.org CC: akpm@linux-foundation.org, "Ursula Braun" , "Julian Wiedmann" , "Martin Schwidefsky" Date: Thu, 01 Jun 2017 16:43:16 +0100 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) Subject: [PATCH 3.16 094/212] s390/qdio: clear DSCI prior to scanning multiple input queues In-Reply-To: X-SA-Exim-Connect-IP: 82.70.136.246 X-SA-Exim-Mail-From: ben@decadent.org.uk X-SA-Exim-Scanned: No (on shadbolt.decadent.org.uk); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2220 Lines: 58 3.16.44-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: Julian Wiedmann commit 1e4a382fdc0ba8d1a85b758c0811de3a3631085e upstream. For devices with multiple input queues, tiqdio_call_inq_handlers() iterates over all input queues and clears the device's DSCI during each iteration. If the DSCI is re-armed during one of the later iterations, we therefore do not scan the previous queues again. The re-arming also raises a new adapter interrupt. But its handler does not trigger a rescan for the device, as the DSCI has already been erroneously cleared. This can result in queue stalls on devices with multiple input queues. Fix it by clearing the DSCI just once, prior to scanning the queues. As the code is moved in front of the loop, we also need to access the DSCI directly (ie irq->dsci) instead of going via each queue's parent pointer to the same irq. This is not a functional change, and a follow-up patch will clean up the other users. In practice, this bug only affects CQ-enabled HiperSockets devices, ie. devices with sysfs-attribute "hsuid" set. Setting a hsuid is needed for AF_IUCV socket applications that use HiperSockets communication. Fixes: 104ea556ee7f ("qdio: support asynchronous delivery of storage blocks") Reviewed-by: Ursula Braun Signed-off-by: Julian Wiedmann Signed-off-by: Martin Schwidefsky Signed-off-by: Ben Hutchings --- drivers/s390/cio/qdio_thinint.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) --- a/drivers/s390/cio/qdio_thinint.c +++ b/drivers/s390/cio/qdio_thinint.c @@ -147,11 +147,11 @@ static inline void tiqdio_call_inq_handl struct qdio_q *q; int i; - for_each_input_queue(irq, q, i) { - if (!references_shared_dsci(irq) && - has_multiple_inq_on_dsci(irq)) - xchg(q->irq_ptr->dsci, 0); + if (!references_shared_dsci(irq) && + has_multiple_inq_on_dsci(irq)) + xchg(irq->dsci, 0); + for_each_input_queue(irq, q, i) { if (q->u.in.queue_start_poll) { /* skip if polling is enabled or already in work */ if (test_and_set_bit(QDIO_QUEUE_IRQS_DISABLED,