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Sergey Ryazanov 01e01f5c89 usb: cdc-wdm: fix reading stuck on device close
cdc-wdm tracks whether a response reading request is in-progress and
blocks the next request from being sent until the previous request is
completed. As soon as last user closes the cdc-wdm device file, the
driver cancels any ongoing requests, resets the pending response
counter, but leaves the response reading in-progress flag
(WDM_RESPONDING) untouched.

So if the user closes the device file during the response receive
request is being performed, no more data will be obtained from the
modem. The request will be cancelled, effectively preventing the
WDM_RESPONDING flag from being reseted. Keeping the flag set will
prevent a new response receive request from being sent, permanently
blocking the read path. The read path will staying blocked until the
module will be reloaded or till the modem will be re-attached.

This stuck has been observed with a Huawei E3372 modem attached to an
OpenWrt router and using the comgt utility to set up a network
connection.

Fix this issue by clearing the WDM_RESPONDING flag on the device file
close.

Without this fix, the device reading stuck can be easily reproduced in a
few connection establishing attempts. With this fix, a load test for
modem connection re-establishing worked for several hours without any
issues.

Fixes: 922a5eadd5 ("usb: cdc-wdm: Fix race between autosuspend and reading from the device")
Signed-off-by: Sergey Ryazanov <ryazanov.s.a@gmail.com>
Cc: stable <stable@vger.kernel.org>
Acked-by: Oliver Neukum <oneukum@suse.com>
Link: https://lore.kernel.org/r/20220501175828.8185-1-ryazanov.s.a@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
History 2022-05-05 22:17:43 +02:00
arch ARM: 2022-05-01 11:49:32 -07:00
block bfq: Fix warning in bfqq_request_over_limit() 2022-04-29 06:45:37 -06:00
certs Kbuild updates for v5.18 2022-03-31 11:59:03 -07:00
crypto for-5.18/64bit-pi-2022-03-25 2022-03-26 12:01:35 -07:00
Documentation ARM: 2022-05-01 11:49:32 -07:00
drivers usb: cdc-wdm: fix reading stuck on device close 2022-05-05 22:17:43 +02:00
fs Driver core fixes for 5.18-rc5 2022-04-30 10:24:21 -07:00
include ARM: 2022-05-01 11:49:32 -07:00
init Kbuild updates for v5.18 2022-03-31 11:59:03 -07:00
ipc fs: allocate inode by using alloc_inode_sb() 2022-03-22 15:57:03 -07:00
kernel Networking fixes for 5.18-rc5, including fixes from bluetooth, bpf 2022-04-28 12:34:50 -07:00
lib - A fix to disable PCI/MSI[-X] masking for XEN_HVM guests as that is 2022-05-01 10:03:36 -07:00
LICENSES LICENSES/LGPL-2.1: Add LGPL-2.1-or-later as valid identifiers 2021-12-16 14:33:10 +01:00
mm kasan: prevent cpu_quarantine corruption when CPU offline and cache shrink occur at same time 2022-04-27 13:28:48 -07:00
net A fix for a NULL dereference that turns out to be easily triggerable 2022-04-29 14:37:35 -07:00
samples dma-mapping updates for Linux 5.18 2022-03-29 08:50:14 -07:00
scripts objtool: Enable unreachable warnings for CLANG LTO 2022-04-19 21:58:48 +02:00
security hardening updates for v5.18-rc1-fix1 2022-03-31 11:43:01 -07:00
sound ALSA: hda/realtek: Add quirk for Clevo NP70PNP 2022-04-21 21:23:47 +02:00
tools - A fix to disable PCI/MSI[-X] masking for XEN_HVM guests as that is 2022-05-01 10:03:36 -07:00
usr Kbuild updates for v5.18 2022-03-31 11:59:03 -07:00
virt Merge branch 'kvm-fixes-for-5.18-rc5' into HEAD 2022-04-29 12:39:34 -04:00
.clang-format genirq/msi: Make interrupt allocation less convoluted 2021-12-16 22:22:20 +01:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.get_maintainer.ignore Opt out of scripts/get_maintainer.pl 2019-05-16 10:53:40 -07:00
.gitattributes .gitattributes: use 'dts' diff driver for dts files 2019-12-04 19:44:11 -08:00
.gitignore .gitignore: ignore only top-level modules.builtin 2021-05-02 00:43:35 +09:00
.mailmap mailmap: update Vasily Averin's email address 2022-04-08 14:20:36 -10:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS MAINTAINERS: replace a Microchip AT91 maintainer 2022-02-09 11:30:01 +01:00
Kbuild kbuild: rename hostprogs-y/always to hostprogs/always-y 2020-02-04 01:53:07 +09:00
Kconfig kbuild: ensure full rebuild when the compiler is updated 2020-05-12 13:28:33 +09:00
MAINTAINERS - A fix to disable PCI/MSI[-X] masking for XEN_HVM guests as that is 2022-05-01 10:03:36 -07:00
Makefile Linux 5.18-rc5 2022-05-01 13:57:58 -07:00
README Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -06:00

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.