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Linux kernel for uConsole
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Salil Mehta 107451b87e net: hns: Fix the stray netpoll locks causing deadlock in NAPI path 
[ Upstream commit bf5a6b4c47 ]

This patch fixes the problem of the spin locks, originally
meant for the netpoll path of hns driver, causing deadlock in
the normal NAPI poll path. The issue happened due to the presence
of the stray leftover spin lock code related to the netpoll,
whose support was earlier removed from the HNS[1], got activated
due to enabling of NET_POLL_CONTROLLER switch.

Earlier background:
The netpoll handling code originally had this bug(as identified
by Marc Zyngier[2]) of wrong spin lock API being used which did
not disable the interrupts and hence could cause locking issues.
i.e. if the lock were first acquired in context to thread like
'ip' util and this lock if ever got later acquired again in
context to the interrupt context like TX/RX (Interrupts could
always pre-empt the lock holding task and acquire the lock again)
and hence could cause deadlock.

Proposed Solution:
1. If the netpoll was enabled in the HNS driver, which is not
   right now, we could have simply used spin_[un]lock_irqsave()
2. But as netpoll is disabled, therefore, it is best to get rid
   of the existing locks and stray code for now. This should
   solve the problem reported by Marc.

[1] https://git.kernel.org/torvalds/c/4bd2c03be7
[2] https://patchwork.ozlabs.org/patch/1189139/

Fixes: 4bd2c03be7 ("net: hns: remove ndo_poll_controller")
Cc: lipeng <lipeng321@huawei.com>
Cc: Yisen Zhuang <yisen.zhuang@huawei.com>
Cc: Eric Dumazet <edumazet@google.com>
Cc: David S. Miller <davem@davemloft.net>
Reported-by: Marc Zyngier <maz@kernel.org>
Acked-by: Marc Zyngier <maz@kernel.org>
Tested-by: Marc Zyngier <maz@kernel.org>
Signed-off-by: Salil Mehta <salil.mehta@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2019-11-12 19:20:33 +01:00
arch arm64: dts: ti: k3-am65-main: Fix gic-its node unit-address 2019-11-10 11:27:56 +01:00
block blk-rq-qos: fix first node deletion of rq_qos_del() 2019-10-29 09:20:09 +01:00
certs export.h: remove VMLINUX_SYMBOL() and VMLINUX_SYMBOL_STR() 2018-08-22 23:21:44 +09:00
crypto crypto: skcipher - Unmap pages after an external error 2019-10-11 18:20:52 +02:00
Documentation x86/xen: Return from panic notifier 2019-11-06 13:05:55 +01:00
drivers net: hns: Fix the stray netpoll locks causing deadlock in NAPI path 2019-11-12 19:20:33 +01:00
firmware kbuild: remove all dummy assignments to obj- 2017-11-18 11:46:06 +09:00
fs cifs: Fix cifsInodeInfo lock_sem deadlock when reconnect occurs 2019-11-10 11:27:34 +01:00
include net: fix data-race in neigh_event_send() 2019-11-12 19:20:28 +01:00
init initramfs: don't free a non-existent initrd 2019-10-01 08:26:09 +02:00
ipc ipc/mqueue.c: only perform resource calculation if user valid 2019-08-06 19:06:52 +02:00
kernel tracing: Fix "gfp_t" format for synthetic events 2019-11-10 11:27:28 +01:00
lib lib: textsearch: fix escapes in example code 2019-10-29 09:19:35 +01:00
LICENSES LICENSES: Remove CC-BY-SA-4.0 license text 2018-10-18 11:28:50 +02:00
mm mm/memory-failure: poison read receives SIGKILL instead of SIGBUS if mmaped more than once 2019-10-29 09:19:59 +01:00
net ipv6: fixes rt6_probe() and fib6_nh->last_probe init 2019-11-12 19:20:33 +01:00
samples samples: bpf: fix: seg fault with NULL pointer arg 2019-11-06 13:05:30 +01:00
scripts scripts/setlocalversion: Improve -dirty check with git-status --no-optional-locks 2019-11-06 13:05:27 +01:00
security ima: fix freeing ongoing ahash_request 2019-10-11 18:21:11 +02:00
sound ASoC: pcm3168a: The codec does not support S32_LE 2019-11-10 11:27:56 +01:00
tools selftests/powerpc: Fix compile error on tlbie_test due to newer gcc 2019-11-10 11:27:55 +01:00
usr kbuild: clean compressed initramfs image 2019-10-07 18:57:16 +02:00
virt KVM: coalesced_mmio: add bounds checking 2019-09-21 07:16:44 +02:00
.clang-format clang-format: Set IndentWrappedFunctionNames false 2018-08-01 18:38:51 +02:00
.cocciconfig
.get_maintainer.ignore
.gitattributes .gitattributes: set git diff driver for C source code files 2016-10-07 18:46:30 -07:00
.gitignore Kbuild updates for v4.17 (2nd) 2018-04-15 17:21:30 -07:00
.mailmap libnvdimm-for-4.19_misc 2018-08-25 18:13:10 -07:00
COPYING COPYING: use the new text with points to the license files 2018-03-23 12:41:45 -06:00
CREDITS 9p: remove Ron Minnich from MAINTAINERS 2018-08-17 16:20:26 -07:00
Kbuild Kbuild updates for v4.15 2017-11-17 17:45:29 -08:00
Kconfig kconfig: move the "Executable file formats" menu to fs/Kconfig.binfmt 2018-08-02 08:06:55 +09:00
MAINTAINERS USB: rio500: Remove Rio 500 kernel driver 2019-10-17 13:44:47 -07:00
Makefile Linux 4.19.83 2019-11-10 11:27:57 +01:00
README Docs: Added a pointer to the formatted docs to README 2018-03-21 09:02:53 -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.
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.