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Rafael J. Wysocki 89ab39da14 cpufreq: Avoid cpufreq_suspend() deadlock on system shutdown
commit 65650b3513 upstream.

It is incorrect to set the cpufreq syscore shutdown callback pointer
to cpufreq_suspend(), because that function cannot be run in the
syscore stage of system shutdown for two reasons: (a) it may attempt
to carry out actions depending on devices that have already been shut
down at that point and (b) the RCU synchronization carried out by it
may not be able to make progress then.

The latter issue has been present since commit 45975c7d21 ("rcu:
Define RCU-sched API in terms of RCU for Tree RCU PREEMPT builds"),
but the former one has been there since commit 90de2a4aa9 ("cpufreq:
suspend cpufreq governors on shutdown") regardless.

Fix that by dropping cpufreq_syscore_ops altogether and making
device_shutdown() call cpufreq_suspend() directly before shutting
down devices, which is along the lines of what system-wide power
management does.

Fixes: 45975c7d21 ("rcu: Define RCU-sched API in terms of RCU for Tree RCU PREEMPT builds")
Fixes: 90de2a4aa9 ("cpufreq: suspend cpufreq governors on shutdown")
Reported-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Tested-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Cc: 4.0+ <stable@vger.kernel.org> # 4.0+
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2019-10-29 09:20:08 +01:00
arch x86/apic/x2apic: Fix a NULL pointer deref when handling a dying cpu 2019-10-29 09:20:04 +01:00
block blk-wbt: fix performance regression in wbt scale_up/scale_down 2019-10-17 13:45:16 -07:00
certs
crypto crypto: skcipher - Unmap pages after an external error 2019-10-11 18:20:52 +02:00
Documentation USB: rio500: Remove Rio 500 kernel driver 2019-10-17 13:44:47 -07:00
drivers cpufreq: Avoid cpufreq_suspend() deadlock on system shutdown 2019-10-29 09:20:08 +01:00
firmware
fs Btrfs: check for the full sync flag while holding the inode lock during fsync 2019-10-29 09:20:07 +01:00
include btrfs: tracepoints: Fix bad entry members of qgroup events 2019-10-29 09:20:07 +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 race in perf_trace_buf initialization 2019-10-29 09:20:03 +01:00
lib lib: textsearch: fix escapes in example code 2019-10-29 09:19:35 +01:00
LICENSES
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 mac80211: Reject malformed SSID elements 2019-10-29 09:19:53 +01:00
samples
scripts namespace: fix namespace.pl script to support relative paths 2019-10-29 09:19:36 +01:00
security ima: fix freeing ongoing ahash_request 2019-10-11 18:21:11 +02:00
sound ASoC: rsnd: Reinitialize bit clock inversion flag for every format setting 2019-10-29 09:19:52 +01:00
tools perf inject jit: Fix JIT_CODE_MOVE filename 2019-10-17 13:45:15 -07:00
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
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.cocciconfig
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MAINTAINERS USB: rio500: Remove Rio 500 kernel driver 2019-10-17 13:44:47 -07:00
Makefile Linux 4.19.80 2019-10-17 13:45:44 -07:00
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.