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Ming Lei 7e70aa789d scsi: core: run queue if SCSI device queue isn't ready and queue is idle
Before commit 0df21c86bd ("scsi: implement .get_budget and .put_budget
for blk-mq"), we run queue after 3ms if queue is idle and SCSI device
queue isn't ready, which is done in handling BLK_STS_RESOURCE. After
commit 0df21c86bd is introduced, queue won't be run any more under
this situation.

IO hang is observed when timeout happened, and this patch fixes the IO
hang issue by running queue after delay in scsi_dev_queue_ready, just
like non-mq. This issue can be triggered by the following script[1].

There is another issue which can be covered by running idle queue: when
.get_budget() is called on request coming from hctx->dispatch_list, if
one request just completes during .get_budget(), we can't depend on
SCSI's restart to make progress any more. This patch fixes the race too.

With this patch, we basically recover to previous behaviour (before
commit 0df21c86bd) of handling idle queue when running out of
resource.

[1] script for test/verify SCSI timeout
rmmod scsi_debug
modprobe scsi_debug max_queue=1

DEVICE=`ls -d /sys/bus/pseudo/drivers/scsi_debug/adapter*/host*/target*/*/block/* | head -1 | xargs basename`
DISK_DIR=`ls -d /sys/block/$DEVICE/device/scsi_disk/*`

echo "using scsi device $DEVICE"
echo "-1" >/sys/bus/pseudo/drivers/scsi_debug/every_nth
echo "temporary write through" >$DISK_DIR/cache_type
echo "128" >/sys/bus/pseudo/drivers/scsi_debug/opts
echo none > /sys/block/$DEVICE/queue/scheduler
dd if=/dev/$DEVICE of=/dev/null bs=1M iflag=direct count=1 &
sleep 5
echo "0" >/sys/bus/pseudo/drivers/scsi_debug/opts
wait
echo "SUCCESS"

Fixes: 0df21c86bd ("scsi: implement .get_budget and .put_budget for blk-mq")
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Tested-by: Holger Hoffstätte <holger@applied-asynchrony.com>
Reviewed-by: Bart Van Assche <bart.vanassche@wdc.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
2017-12-07 19:52:55 -05:00
arch pci-v4.15-changes 2017-11-15 15:01:28 -08:00
block Merge branch 'for-next' of git://git.kernel.org/pub/scm/linux/kernel/git/shli/md 2017-11-14 16:07:26 -08:00
certs License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
crypto Merge branch 'linus' of git://git.kernel.org/pub/scm/linux/kernel/git/herbert/crypto-2.6 2017-11-14 10:52:09 -08:00
Documentation IPMI updates for 4.15 2017-11-15 15:12:28 -08:00
drivers scsi: core: run queue if SCSI device queue isn't ready and queue is idle 2017-12-07 19:52:55 -05:00
firmware License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
fs Modules updates for v4.15 2017-11-15 13:46:33 -08:00
include scsi: libsas: align sata_device's rps_resp on a cacheline 2017-11-21 23:06:32 -05:00
init pci-v4.15-changes 2017-11-15 15:01:28 -08:00
ipc License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
kernel Merge branch 'for-4.15' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup 2017-11-15 14:29:44 -08:00
lib Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next 2017-11-15 11:56:19 -08:00
mm Merge branch 'for-4.15' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/percpu 2017-11-15 14:17:11 -08:00
net Modules updates for v4.15 2017-11-15 13:46:33 -08:00
samples Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next 2017-11-15 11:56:19 -08:00
scripts Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next 2017-11-15 11:56:19 -08:00
security Modules updates for v4.15 2017-11-15 13:46:33 -08:00
sound sound updates for 4.15-rc1 2017-11-14 18:01:46 -08:00
tools Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next 2017-11-15 11:56:19 -08:00
usr initramfs: fix initramfs rebuilds w/ compression after disabling 2017-11-03 07:39:19 -07:00
virt arm64 updates for 4.15 2017-11-15 10:56:56 -08:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.get_maintainer.ignore Add hch to .get_maintainer.ignore 2015-08-21 14:30:10 -07:00
.gitattributes .gitattributes: set git diff driver for C source code files 2016-10-07 18:46:30 -07:00
.gitignore .gitignore: move *.dtb and *.dtb.S patterns to the top-level .gitignore 2017-11-08 11:20:24 -06:00
.mailmap .mailmap: Add Maciej W. Rozycki's Imagination e-mail address 2017-11-10 12:16:15 -08:00
COPYING [PATCH] update FSF address in COPYING 2005-09-10 10:06:29 -07:00
CREDITS MAINTAINERS: update TPM driver infrastructure changes 2017-11-09 17:58:40 -08:00
Kbuild License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
Kconfig License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
MAINTAINERS pci-v4.15-changes 2017-11-15 15:01:28 -08:00
Makefile RISC-V Port for Linux 4.15 v9 2017-11-15 10:49:15 -08:00
README README: add a new README file, pointing to the Documentation/ 2016-10-24 08:12:35 -02:00

Linux kernel
============

This file was moved to Documentation/admin-guide/README.rst

Please notice that there are several guides for kernel developers and users.
These guides can be rendered in a number of formats, like HTML and PDF.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
See Documentation/00-INDEX for a list of what is contained in each file.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.