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Groups > linux.kernel > #1599095

[PATCH 4.4 07/36] s390/qdio: clear DSCI prior to scanning multiple input queues

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4.4-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Julian Wiedmann <jwi@linux.vnet.ibm.com>

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 <ubraun@linux.vnet.ibm.com>
Signed-off-by: Julian Wiedmann <jwi@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 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,

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[PATCH 4.4 00/36] 4.4.54-stable review Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-03-13 09:50 +0100
  [PATCH 4.4 18/36] ktest: Fix child exit code processing Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-03-13 09:50 +0100
  [PATCH 4.4 11/36] s390: use correct input data address for setup_randomness Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-03-13 09:50 +0100
  [PATCH 4.4 27/36] drm/ast: Call open_key before enable_mmio in POST code Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-03-13 09:50 +0100
  [PATCH 4.4 05/36] KVM: VMX: use correct vmcs_read/write for guest segment selector/base Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-03-13 09:50 +0100
  [PATCH 4.4 31/36] drm/atomic: fix an error code in mode_fixup() Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-03-13 10:20 +0100
  [PATCH 4.4 35/36] fat: fix using uninitialized fields of fat_inode/fsinfo_inode Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-03-13 10:20 +0100
  [PATCH 4.4 08/36] s390/dcssblk: fix device size calculation in dcssblk_direct_access() Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-03-13 10:20 +0100
  [PATCH 4.4 07/36] s390/qdio: clear DSCI prior to scanning multiple input queues Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-03-13 10:20 +0100
  [PATCH 4.4 04/36] KVM: s390: Disable dirty log retrieval for UCONTROL guests Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-03-13 10:20 +0100
  [PATCH 4.4 36/36] drivers: hv: Turn off write permission on the hypercall page Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-03-13 10:20 +0100
  [PATCH 4.4 34/36] libceph: use BUG() instead of BUG_ON(1) Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-03-13 10:20 +0100
  [PATCH 4.4 23/36] xtensa: move parse_tag_fdt out of #ifdef CONFIG_BLK_DEV_INITRD Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-03-13 10:30 +0100
  [PATCH 4.4 22/36] pwm: pca9685: Fix period change with same duty cycle Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-03-13 10:30 +0100
  [PATCH 4.4 19/36] ceph: remove req from unsafe list when unregistering it Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-03-13 10:30 +0100
  [PATCH 4.4 26/36] drm/ast: Fix test for VGA enabled Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-03-13 10:30 +0100
  [PATCH 4.4 17/36] IB/srp: Fix race conditions related to task management Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-03-13 10:30 +0100
  [PATCH 4.4 15/36] IB/IPoIB: Add destination address when re-queue packet Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-03-13 10:30 +0100
  [PATCH 4.4 32/36] fakelb: fix schedule while atomic Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-03-13 10:30 +0100
  [PATCH 4.4 21/36] nlm: Ensure callback code also checks that the files match Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-03-13 10:30 +0100
  [PATCH 4.4 13/36] mnt: Tuck mounts under others instead of creating shadow/side mounts. Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-03-13 10:30 +0100
  [PATCH 4.4 20/36] target: Fix NULL dereference during LUN lookup + active I/O shutdown Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-03-13 10:30 +0100
  [PATCH 4.4 24/36] mac80211: flush delayed work when entering suspend Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-03-13 10:30 +0100
  [PATCH 4.4 12/36] net: mvpp2: fix DMA address calculation in mvpp2_txq_inc_put() Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-03-13 10:30 +0100
  [PATCH 4.4 10/36] s390: make setup_randomness work Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-03-13 10:30 +0100
  Re: [PATCH 4.4 00/36] 4.4.54-stable review Guenter Roeck <linux@roeck-us.net> - 2017-03-13 23:40 +0100

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