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Johannes Berg a59a7b96dc iwlwifi: pcie: reschedule in long-running memory reads 
[ Upstream commit 3d372c4edf ]

If we spin for a long time in memory reads that (for some reason in
hardware) take a long time, then we'll eventually get messages such
as

  watchdog: BUG: soft lockup - CPU#2 stuck for 24s! [kworker/2:2:272]

This is because the reading really does take a very long time, and
we don't schedule, so we're hogging the CPU with this task, at least
if CONFIG_PREEMPT is not set, e.g. with CONFIG_PREEMPT_VOLUNTARY=y.

Previously I misinterpreted the situation and thought that this was
only going to happen if we had interrupts disabled, and then fixed
this (which is good anyway, however), but that didn't always help;
looking at it again now I realized that the spin unlock will only
reschedule if CONFIG_PREEMPT is used.

In order to avoid this issue, change the code to cond_resched() if
we've been spinning for too long here.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Fixes: 04516706bb ("iwlwifi: pcie: limit memory read spin time")
Signed-off-by: Luca Coelho <luciano.coelho@intel.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
Link: https://lore.kernel.org/r/iwlwifi.20210115130253.217a9d6a6a12.If964cb582ab0aaa94e81c4ff3b279eaafda0fd3f@changeid
Signed-off-by: Sasha Levin <sashal@kernel.org>
2021-02-03 23:28:47 +01:00
arch powerpc/64s: prevent recursive replay_soft_interrupts causing superfluous interrupt 2021-02-03 23:28:46 +01:00
block blk-mq: test QUEUE_FLAG_HCTX_ACTIVE for sbitmap_shared in hctx_may_queue 2021-02-03 23:28:44 +01:00
certs .gitignore: add SPDX License Identifier 2020-03-25 11:50:48 +01:00
crypto crypto: xor - Fix divide error in do_xor_speed() 2021-01-27 11:54:52 +01:00
Documentation KVM: Documentation: Fix spec for KVM_CAP_ENABLE_CAP_VM 2021-02-03 23:28:43 +01:00
drivers iwlwifi: pcie: reschedule in long-running memory reads 2021-02-03 23:28:47 +01:00
fs pNFS/NFSv4: Update the layout barrier when we schedule a layoutreturn 2021-02-03 23:28:47 +01:00
include ASoC: dt-bindings: lpass: Fix and common up lpass dai ids 2021-02-03 23:28:46 +01:00
init rcu-tasks: Move RCU-tasks initialization to before early_initcall() 2021-01-19 18:27:28 +01:00
ipc ipc: adjust proc_ipc_sem_dointvec definition to match prototype 2020-09-05 12:14:29 -07:00
kernel PM: hibernate: flush swap writer after marking 2021-02-03 23:28:40 +01:00
lib iov_iter: fix the uaccess area in copy_compat_iovec_from_user 2021-01-27 11:55:09 +01:00
LICENSES LICENSES/deprecated: add Zlib license text 2020-09-16 14:33:49 +02:00
mm mm: fix a race on nr_swap_pages 2021-01-30 13:55:19 +01:00
net xfrm: Fix wraparound in xfrm_policy_addr_delta() 2021-02-03 23:28:45 +01:00
samples samples/bpf: Fix possible hang in xdpsock with multiple threads 2020-12-30 11:53:49 +01:00
scripts Revert "kconfig: remove 'kvmconfig' and 'xenconfig' shorthands" 2021-01-23 16:03:57 +01:00
security dump_common_audit_data(): fix racy accesses to ->d_name 2021-01-19 18:27:29 +01:00
sound ASoC: qcom: lpass: Fix out-of-bounds DAI ID lookup 2021-02-03 23:28:47 +01:00
tools xfrm: Fix wraparound in xfrm_policy_addr_delta() 2021-02-03 23:28:45 +01:00
usr Merge branch 'work.fdpic' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2020-08-07 13:29:39 -07:00
virt KVM: Forbid the use of tagged userspace addresses for memslots 2021-02-03 23:28:41 +01:00
.clang-format RDMA 5.10 pull request 2020-10-17 11:18:18 -07:00
.cocciconfig
.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: docs: ignore sphinx_*/ directories 2020-09-10 10:44:31 -06:00
.mailmap mailmap: add two more addresses of Uwe Kleine-König 2020-12-06 10:19:07 -08:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS MAINTAINERS: Move Jason Cooper to CREDITS 2020-11-30 10:20:34 +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 Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2020-12-10 15:30:13 -08:00
Makefile Linux 5.10.12 2021-01-30 13:55:20 +01:00
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.