linux/drivers/cpufreq
Viresh Kumar c443563036 cpufreq: governor: New sysfs show/store callbacks for governor tunables
The ondemand and conservative governors use the global-attr or freq-attr
structures to represent sysfs attributes corresponding to their tunables
(which of them is actually used depends on whether or not different
policy objects can use the same governor with different tunables at the
same time and, consequently, on where those attributes are located in
sysfs).

Unfortunately, in the freq-attr case, the standard cpufreq show/store
sysfs attribute callbacks are applied to the governor tunable attributes
and they always acquire the policy->rwsem lock before carrying out the
operation.  That may lead to an ABBA deadlock if governor tunable
attributes are removed under policy->rwsem while one of them is being
accessed concurrently (if sysfs attributes removal wins the race, it
will wait for the access to complete with policy->rwsem held while the
attribute callback will block on policy->rwsem indefinitely).

We attempted to address this issue by dropping policy->rwsem around
governor tunable attributes removal (that is, around invocations of the
->governor callback with the event arg equal to CPUFREQ_GOV_POLICY_EXIT)
in cpufreq_set_policy(), but that opened up race conditions that had not
been possible with policy->rwsem held all the time.  Therefore
policy->rwsem cannot be dropped in cpufreq_set_policy() at any point,
but the deadlock situation described above must be avoided too.

To that end, use the observation that in principle governor tunables may
be represented by the same data type regardless of whether the governor
is system-wide or per-policy and introduce a new structure, struct
governor_attr, for representing them and new corresponding macros for
creating show/store sysfs callbacks for them.  Also make their parent
kobject use a new kobject type whose default show/store callbacks are
not related to the standard core cpufreq ones in any way (and they don't
acquire policy->rwsem in particular).

Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Tested-by: Juri Lelli <juri.lelli@arm.com>
Tested-by: Shilpasri G Bhat <shilpa.bhat@linux.vnet.ibm.com>
[ rjw: Subject & changelog + rebase ]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2016-03-09 14:40:58 +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: Rearrange governor data structures 2016-03-09 14:40:56 +01:00
arm_big_little_dt.c PM / OPP: Prefix exported opp routines with dev_pm_opp_ 2015-09-15 02:03:16 +02:00
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
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_conservative.c cpufreq: governor: New sysfs show/store callbacks for governor tunables 2016-03-09 14:40:58 +01:00
cpufreq_governor.c cpufreq: governor: New sysfs show/store callbacks for governor tunables 2016-03-09 14:40:58 +01:00
cpufreq_governor.h cpufreq: governor: New sysfs show/store callbacks for governor tunables 2016-03-09 14:40:58 +01:00
cpufreq_ondemand.c cpufreq: governor: New sysfs show/store callbacks for governor tunables 2016-03-09 14:40:58 +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: stats: drop unnecessary locking 2015-01-23 23:06:45 +01:00
cpufreq_userspace.c cpufreq: Clean up default and fallback governor setup 2016-02-05 02:37:42 +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: Add mechanism for registering utilization update callbacks 2016-03-09 14:39:19 +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 cpufreq: hisilicon: add acpu driver 2015-04-02 02:24:54 +02:00
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 cpufreq: qoriq: rename the driver 2015-03-18 22:35:16 +01:00
Kconfig.x86 Revert "cpufreq: intel_pstate: Use ACPI perf configuration" 2015-11-19 00:20:42 +01:00
kirkwood-cpufreq.c
longhaul.c Update/Remove soon-to-be-dead email address 2014-12-19 12:56:15 -08:00
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 Update/Remove soon-to-be-dead email address 2014-12-19 12:56:15 -08:00
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_pervasive.c
ppc_cbe_cpufreq_pmi.c cpufreq: remove redundant CPUFREQ_INCOMPATIBLE notifier event 2015-09-01 15:50:38 +02:00
ppc_cbe_cpufreq.c
ppc_cbe_cpufreq.h
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 cpufreq: s3c: remove incorrect __init annotations 2015-02-19 06:36:53 +01:00
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 cpufreq: speedstep-smi: enable interrupts when waiting 2015-02-12 02:02:52 +01:00
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