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Hans de Goede bcf0595789 Input: soc_button_array - partial revert of support for newer surface devices 
Commit c394159310 ("Input: soc_button_array - add support for newer
surface devices") not only added support for the MSHW0040 ACPI HID,
but for some reason it also makes changes to the error handling of the
soc_button_lookup_gpio() call in soc_button_device_create(). Note ideally
this seamingly unrelated change would have been made in a separate commit,
with a message explaining the what and why of this change.

I guess this change may have been added to deal with -EPROBE_DEFER errors,
but in case of the existing support for PNP0C40 devices, treating
-EPROBE_DEFER as any other error is deliberate, see the comment this
commit adds for why.

The actual returning of -EPROBE_DEFER to the caller of soc_button_probe()
introduced by the new error checking causes a serious regression:

On devices with so called virtual GPIOs soc_button_lookup_gpio() will
always return -EPROBE_DEFER for these fake GPIOs, when this happens
during the second call of soc_button_device_create() we already have
successfully registered our first child. This causes the kernel to think
we are making progress with probing things even though we unregister the
child before again before we return the -EPROBE_DEFER. Since we are making
progress the kernel will retry deferred-probes again immediately ending
up stuck in a loop with the following showing in dmesg:

[  124.022697] input: gpio-keys as /devices/platform/INTCFD9:00/gpio-keys.0.auto/input/input6537
[  124.040764] input: gpio-keys as /devices/platform/INTCFD9:00/gpio-keys.0.auto/input/input6538
[  124.056967] input: gpio-keys as /devices/platform/INTCFD9:00/gpio-keys.0.auto/input/input6539
[  124.072143] input: gpio-keys as /devices/platform/INTCFD9:00/gpio-keys.0.auto/input/input6540
[  124.092373] input: gpio-keys as /devices/platform/INTCFD9:00/gpio-keys.0.auto/input/input6541
[  124.108065] input: gpio-keys as /devices/platform/INTCFD9:00/gpio-keys.0.auto/input/input6542
[  124.128483] input: gpio-keys as /devices/platform/INTCFD9:00/gpio-keys.0.auto/input/input6543
[  124.147141] input: gpio-keys as /devices/platform/INTCFD9:00/gpio-keys.0.auto/input/input6544
[  124.165070] input: gpio-keys as /devices/platform/INTCFD9:00/gpio-keys.0.auto/input/input6545
[  124.179775] input: gpio-keys as /devices/platform/INTCFD9:00/gpio-keys.0.auto/input/input6546
[  124.202726] input: gpio-keys as /devices/platform/INTCFD9:00/gpio-keys.0.auto/input/input6547
<continues on and on and on>

And 1 CPU core being stuck at 100% and udev hanging since it is waiting
for the modprobe of soc_button_array to return.

This patch reverts the soc_button_lookup_gpio() error handling changes,
fixing this regression.

Fixes: c394159310 ("Input: soc_button_array - add support for newer surface devices")
BugLink: https://bugzilla.kernel.org/show_bug.cgi?id=205031
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Tested-by: Maximilian Luz <luzmaximilian@gmail.com>
Acked-by: Maximilian Luz <luzmaximilian@gmail.com>
Link: https://lore.kernel.org/r/20191005105551.353273-1-hdegoede@redhat.com
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
2019-10-08 16:45:56 -07:00
arch ARM: ux500: improve BU21013 touchpad bindings 2019-09-02 09:06:51 -07:00
block block, bfq: handle NULL return value by bfq_init_rq() 2019-08-08 07:31:50 -06:00
certs Revert "Merge tag 'keys-acl-20190703' of git://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-fs" 2019-07-10 18:43:43 -07:00
crypto USB / PHY patches for 5.3-rc1 2019-07-11 15:40:06 -07:00
Documentation Input: bu21013_ts - switch to using standard touchscreen properties 2019-09-02 09:07:38 -07:00
drivers Input: soc_button_array - partial revert of support for newer surface devices 2019-10-08 16:45:56 -07:00
fs dax fixes v5.3-rc4 2019-08-11 13:15:10 -07:00
include Merge branch 'next' into for-linus 2019-09-16 09:56:27 -07:00
init Merge branch 'work.mount0' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2019-07-19 10:42:02 -07:00
ipc Merge branch 'work.mount0' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2019-07-19 10:42:02 -07:00
kernel Merge branch 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2019-08-10 15:48:02 -07:00
lib Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2019-08-06 17:11:59 -07:00
LICENSES LICENSES: Rename other to deprecated 2019-05-03 06:34:32 -06:00
mm mm/memremap: Fix reuse of pgmap instances with internal references 2019-08-09 14:16:15 -07:00
net net: dsa: sja1105: Fix memory leak on meta state machine error path 2019-08-06 14:37:02 -07:00
samples treewide: remove SPDX "WITH Linux-syscall-note" from kernel-space headers again 2019-07-25 11:05:10 +02:00
scripts kbuild: show hint if subdir-y/m is used to visit module Makefile 2019-08-10 01:45:31 +09:00
security selinux/stable-5.3 PR 20190801 2019-08-02 18:40:49 -07:00
sound sound fixes for 5.3-rc4 2019-08-09 09:21:27 -07:00
tools Merge branch 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2019-08-10 16:19:02 -07:00
usr kbuild: enable arch/s390/include/uapi/asm/zcrypt.h for uapi header test 2019-07-23 10:45:46 +02:00
virt KVM/arm fixes for 5.3, take #2 2019-08-09 16:53:50 +02:00
.clang-format Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2019-04-17 11:26:25 -07:00
.cocciconfig
.get_maintainer.ignore Opt out of scripts/get_maintainer.pl 2019-05-16 10:53:40 -07:00
.gitattributes
.gitignore .gitignore: Add compilation database file 2019-07-27 12:18:19 +09:00
.mailmap MAINTAINERS: Update my email address 2019-07-22 14:57:50 +01:00
COPYING COPYING: use the new text with points to the license files 2018-03-23 12:41:45 -06:00
CREDITS Remove references to dead website. 2019-07-19 12:22:04 -07:00
Kbuild Kbuild updates for v5.1 2019-03-10 17:48:21 -07:00
Kconfig docs: kbuild: convert docs to ReST and rename to *.rst 2019-06-14 14:21:21 -06:00
MAINTAINERS Linux 5.3-rc4 2019-08-11 23:24:46 -07:00
Makefile Linux 5.3-rc4 2019-08-11 13:26:41 -07:00
README Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -06:00

README 

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

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.

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.