redonkable/alistair23-linux
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alistair23-linux/drivers/cpufreq
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Rafael J. Wysocki 27de348239 cpufreq: governor: Fix race in dbs_update_util_handler() 
There is a scenario that may lead to undesired results in
dbs_update_util_handler().  Namely, if two CPUs sharing a policy
enter the funtion at the same time, pass the sample delay check
and then one of them is stalled until dbs_work_handler() (queued
up by the other CPU) clears the work counter, it may update the
work counter and queue up another work item prematurely.

To prevent that from happening, use the observation that the CPU
queuing up a work item in dbs_update_util_handler() updates the
last sample time.  This means that if another CPU was stalling after
passing the sample delay check and now successfully updated the work
counter as a result of the race described above, it will see the new
value of the last sample time which is different from what it used in
the sample delay check before.  If that happens, the sample delay
check passed previously is not valid any more, so the CPU should not
continue.

Fixes: f17cbb53783c (cpufreq: governor: Avoid atomic operations in hot paths)
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
2016-03-09 14:41:10 +01:00
..
acpi-cpufreq.c cpufreq: Simplify core code related to boost support 2016-01-01 03:49:51 +01:00
amd_freq_sensitivity.c cpufreq: governor: Make governor private data per-policy 2016-03-09 14:41:08 +01:00
arm_big_little.c cpufreq: arm_big_little: Add support to register a cpufreq cooling device 2015-12-10 00:14:58 +01:00
arm_big_little.h PM / OPP: Prefix exported opp routines with dev_pm_opp_ 2015-09-15 02:03:16 +02:00
arm_big_little_dt.c PM / OPP: Prefix exported opp routines with dev_pm_opp_ 2015-09-15 02:03:16 +02:00
at32ap-cpufreq.c
blackfin-cpufreq.c blackfin-cpufreq: Mark cpu_set_cclk() as static 2015-12-28 01:51:36 +01:00
cppc_cpufreq.c cpufreq: CPPC: Initialize and check CPUFreq CPU co-ord type correctly 2015-11-23 22:21:18 +01:00
cpufreq-dt.c cpufreq: cpufreq-dt: avoid uninitialized variable warnings: 2016-01-27 23:23:54 +01:00
cpufreq-nforce2.c cpufreq: nforce2: Fix typo in comment to function nforce2_init() 2015-06-15 15:45:24 +02:00
cpufreq.c cpufreq: Remove cpufreq_governor_lock 2016-03-09 14:41:01 +01:00
cpufreq_conservative.c cpufreq: governor: Relocate definitions of tuners structures 2016-03-09 14:41:09 +01:00
cpufreq_governor.c cpufreq: governor: Fix race in dbs_update_util_handler() 2016-03-09 14:41:10 +01:00
cpufreq_governor.h cpufreq: governor: Make dbs_data_mutex static 2016-03-09 14:41:09 +01:00
cpufreq_ondemand.c cpufreq: governor: Move per-CPU data to the common code 2016-03-09 14:41:09 +01:00
cpufreq_ondemand.h cpufreq: governor: Relocate definitions of tuners structures 2016-03-09 14:41:09 +01:00
cpufreq_performance.c cpufreq: Clean up default and fallback governor setup 2016-02-05 02:37:42 +01:00
cpufreq_powersave.c cpufreq: Clean up default and fallback governor setup 2016-02-05 02:37:42 +01:00
cpufreq_stats.c
cpufreq_userspace.c cpufreq: Clean up default and fallback governor setup 2016-02-05 02:37:42 +01:00
cris-artpec3-cpufreq.c
cris-etraxfs-cpufreq.c
davinci-cpufreq.c
dbx500-cpufreq.c
e_powersaver.c ACPI / processor: Drop an unused argument of a cleanup routine 2015-07-22 22:11:16 +02:00
elanfreq.c
exynos5440-cpufreq.c PM / OPP: Prefix exported opp routines with dev_pm_opp_ 2015-09-15 02:03:16 +02:00
freq_table.c cpufreq: Allow drivers to enable boost support after registering driver 2015-08-07 03:25:23 +02:00
gx-suspmod.c cpufreq: gx-suspmod: Fix two typos in two comments 2015-06-15 15:46:15 +02:00
highbank-cpufreq.c
hisi-acpu-cpufreq.c
ia64-acpi-cpufreq.c cpufreq: ia64: Fix a memory leak in acpi_cpufreq_cpu_exit() 2015-07-22 22:27:40 +02:00
imx6q-cpufreq.c Merge branch 'pm-opp' 2015-11-02 00:54:37 +01:00
integrator-cpufreq.c cpufreq: integrator: Fix module autoload for OF platform driver 2015-09-25 23:29:35 +02:00
intel_pstate.c cpufreq: intel_pstate: Replace timers with utilization update callbacks 2016-03-09 14:40:52 +01:00
Kconfig cpufreq: governor: Replace timers with utilization update callbacks 2016-03-09 14:40:53 +01:00
Kconfig.arm Merge back earlier cpufreq material for v4.5. 2015-12-21 03:15:15 +01:00
Kconfig.powerpc
Kconfig.x86 Revert "cpufreq: intel_pstate: Use ACPI perf configuration" 2015-11-19 00:20:42 +01:00
kirkwood-cpufreq.c
longhaul.c
longhaul.h
longrun.c
loongson2_cpufreq.c CPUFREQ: Loongson2: Fix broken build due to incorrect include. 2015-08-03 09:24:59 +02:00
ls1x-cpufreq.c MIPS: Loongson: Naming style cleanup and rework 2015-06-21 21:53:59 +02:00
Makefile cpufreq: st: Provide runtime initialised driver for ST's platforms 2015-12-12 02:55:21 +01:00
maple-cpufreq.c
mt8173-cpufreq.c cpufreq: mt8173: migrate to use operating-points-v2 bindings 2016-01-02 00:49:33 +01:00
omap-cpufreq.c
p4-clockmod.c p4-clockmod: Replace cpu_sibling_mask() with topology_sibling_cpumask() 2015-05-27 15:22:16 +02:00
pasemi-cpufreq.c
pcc-cpufreq.c cpufreq: pcc-cpufreq: update default value of cpuinfo_transition_latency 2015-12-10 00:17:03 +01:00
pmac32-cpufreq.c
pmac64-cpufreq.c
powernow-k6.c
powernow-k7.c ACPI / processor: Drop an unused argument of a cleanup routine 2015-07-22 22:11:16 +02:00
powernow-k7.h
powernow-k8.c ACPI / processor: Drop an unused argument of a cleanup routine 2015-07-22 22:11:16 +02:00
powernow-k8.h
powernv-cpufreq.c powerpc/powernv: remove FW_FEATURE_OPALv3 and just use FW_FEATURE_OPAL 2015-12-17 22:40:54 +11:00
ppc_cbe_cpufreq.c
ppc_cbe_cpufreq.h
ppc_cbe_cpufreq_pervasive.c
ppc_cbe_cpufreq_pmi.c cpufreq: remove redundant CPUFREQ_INCOMPATIBLE notifier event 2015-09-01 15:50:38 +02:00
pxa2xx-cpufreq.c cpufreq: pxa2xx: fix pxa_cpufreq_change_voltage prototype 2016-01-27 23:22:50 +01:00
pxa3xx-cpufreq.c
qoriq-cpufreq.c cpufreq: qoriq: Register cooling device based on device tree 2015-12-10 00:19:35 +01:00
s3c24xx-cpufreq-debugfs.c
s3c24xx-cpufreq.c cpufreq: s3c24xx: Do not mark s3c2410_plls_add as __init 2015-11-27 10:10:32 +09:00
s3c64xx-cpufreq.c
s3c2410-cpufreq.c
s3c2412-cpufreq.c
s3c2416-cpufreq.c
s3c2440-cpufreq.c
s5pv210-cpufreq.c cpufreq: s5pv210-cpufreq: fix wrong do_div() usage 2015-11-05 22:50:48 +01:00
sa1100-cpufreq.c
sa1110-cpufreq.c
sc520_freq.c
scpi-cpufreq.c cpufreq: scpi-cpufreq: signedness bug in scpi_get_dvfs_info() 2015-12-24 02:11:37 +01:00
sfi-cpufreq.c cpufreq: sfi: use kmemdup rather than duplicating its implementation 2015-09-01 15:51:15 +02:00
sh-cpufreq.c
sparc-us2e-cpufreq.c
sparc-us3-cpufreq.c
spear-cpufreq.c
speedstep-centrino.c
speedstep-ich.c speedstep-ich: Replace cpu_sibling_mask() with topology_sibling_cpumask() 2015-05-27 15:22:16 +02:00
speedstep-lib.c cpufreq: speedstep-lib: Use monotonic clock 2015-09-01 15:51:43 +02:00
speedstep-lib.h
speedstep-smi.c
sti-cpufreq.c cpufreq: st: Provide runtime initialised driver for ST's platforms 2015-12-12 02:55:21 +01:00
tegra20-cpufreq.c cpufreq: tegra20: remove superfluous CONFIG_PM ifdefs 2015-09-26 03:00:57 +02:00
tegra124-cpufreq.c cpufreq: Add cpufreq driver for Tegra124 2015-07-16 09:34:09 +02:00
unicore2-cpufreq.c
vexpress-spc-cpufreq.c