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linux/drivers/cpufreq
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Rafael J. Wysocki 559ed40752 cpufreq: Avoid attempts to create duplicate symbolic links 
After commit 87549141d5 (cpufreq: Stop migrating sysfs files on
hotplug) there is a problem with CPUs that share cpufreq policy
objects with other CPUs and are initially offline.

Say CPU1 shares a policy with CPU0 which is online and is registered
first.  As part of the registration process, cpufreq_add_dev() is
called for it.  It creates the policy object and a symbolic link
to it from the CPU1's sysfs directory.  If CPU1 is registered
subsequently and it is offline at that time, cpufreq_add_dev() will
attempt to create a symbolic link to the policy object for it, but
that link is present already, so a warning about that will be
triggered.

To avoid that warning, make cpufreq use an additional CPU mask
containing related CPUs that are actually present for each policy
object.  That mask is initialized when the policy object is populated
after its creation (for the first online CPU using it) and it includes
CPUs from the "policy CPUs" mask returned by the cpufreq driver's
->init() callback that are physically present at that time.  Symbolic
links to the policy are created only for the CPUs in that mask.

If cpufreq_add_dev() is invoked for an offline CPU, it checks the
new mask and only creates the symlink if the CPU was not in it (the
CPU is added to the mask at the same time).

In turn, cpufreq_remove_dev() drops the given CPU from the new mask,
removes its symlink to the policy object and returns, unless it is
the CPU owning the policy object.  In that case, the policy object
is moved to a new CPU's sysfs directory or deleted if the CPU being
removed was the last user of the policy.

While at it, notice that cpufreq_remove_dev() can't fail, because
its return value is ignored, so make it ignore return values from
__cpufreq_remove_dev_prepare() and __cpufreq_remove_dev_finish()
and prevent these functions from aborting on errors returned by
__cpufreq_governor().  Also drop the now unused sif argument from
them.

Fixes: 87549141d5 (cpufreq: Stop migrating sysfs files on hotplug)
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Reported-and-tested-by: Russell King <linux@arm.linux.org.uk>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
2015-07-28 17:19:26 +02:00
..
acpi-cpufreq.c acpi-cpufreq: Replace cpu_**_mask() with topology_**_cpumask() 2015-05-27 15:22:16 +02:00
amd_freq_sensitivity.c cpufreq: AMD "frequency sensitivity feedback" powersave bias for ondemand governor 2013-04-10 13:19:26 +02:00
arm_big_little_dt.c Driver core patches for 3.19-rc1 2014-12-14 16:10:09 -08:00
arm_big_little.c cpufreq: arm_big_little: remove compile-time dependency on BIG_LITTLE 2015-05-15 01:53:42 +02:00
arm_big_little.h cpufreq: arm_big_little: free OPP table created during ->init() 2014-12-02 00:01:24 +01:00
at32ap-cpufreq.c cpufreq: at32ap: don't declare local variable as static 2014-04-07 14:31:33 +02:00
blackfin-cpufreq.c cpufreq: Remove cpufreq_generic_exit() 2014-03-12 01:06:00 +01:00
cpufreq_conservative.c cpufreq: governor: Serialize governor callbacks 2015-06-15 15:42:53 +02:00
cpufreq_governor.c cpufreq: governor: Serialize governor callbacks 2015-06-15 15:42:53 +02:00
cpufreq_governor.h cpufreq: governor: Serialize governor callbacks 2015-06-15 15:42:53 +02:00
cpufreq_ondemand.c cpufreq: governor: Serialize governor callbacks 2015-06-15 15:42:53 +02:00
cpufreq_opp.c cpufreq / OPP: Fix the order of arguments for kcalloc() 2014-09-08 00:02:58 +02:00
cpufreq_performance.c cpufreq: Clean up header files included in the core 2013-08-07 23:34:09 +02:00
cpufreq_powersave.c cpufreq: Clean up header files included in the core 2013-08-07 23:34:09 +02:00
cpufreq_stats.c cpufreq: stats: drop unnecessary locking 2015-01-23 23:06:45 +01:00
cpufreq_userspace.c cpufreq / governor: Remove fossil comment 2013-10-17 23:00:20 +02:00
cpufreq-dt.c cpufreq: dt: allow driver to boot automatically 2015-06-17 00:02:34 +02:00
cpufreq-nforce2.c cpufreq: nforce2: Fix typo in comment to function nforce2_init() 2015-06-15 15:45:24 +02:00
cpufreq.c cpufreq: Avoid attempts to create duplicate symbolic links 2015-07-28 17:19:26 +02:00
cris-artpec3-cpufreq.c cpufreq: create another field .flags in cpufreq_frequency_table 2014-04-07 14:43:50 +02:00
cris-etraxfs-cpufreq.c cpufreq: create another field .flags in cpufreq_frequency_table 2014-04-07 14:43:50 +02:00
davinci-cpufreq.c cpufreq: drop owner assignment from platform_drivers 2014-10-20 16:20:24 +02:00
dbx500-cpufreq.c cpufreq: drop owner assignment from platform_drivers 2014-10-20 16:20:24 +02:00
e_powersaver.c cpufreq: add 'freq_table' in struct cpufreq_policy 2014-03-12 01:06:00 +01:00
elanfreq.c cpufreq: Use cpufreq_for_each_* macros for frequency table iteration 2014-04-30 00:06:21 +02:00
exynos4x12-cpufreq.c cpufreq: cpu0: rename driver and internals to 'cpufreq_dt' 2014-10-03 15:37:54 +02:00
exynos5250-cpufreq.c cpufreq: cpu0: rename driver and internals to 'cpufreq_dt' 2014-10-03 15:37:54 +02:00
exynos5440-cpufreq.c Driver core patches for 3.19-rc1 2014-12-14 16:10:09 -08:00
exynos-cpufreq.c Fix up implicit <module.h> users that will break later. 2015-07-02 10:25:22 -07:00
exynos-cpufreq.h cpufreq: exynos: remove Exynos4210 specific cpufreq driver support 2015-06-20 12:17:44 -07:00
freq_table.c cpufreq: Allow freq_table to be obtained for offline CPUs 2015-07-10 01:43:27 +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 Merge branch 'mailbox-for-linus' of git://git.linaro.org/landing-teams/working/fujitsu/integration 2014-10-21 11:21:19 -07:00
hisi-acpu-cpufreq.c cpufreq: hisilicon: add acpu driver 2015-04-02 02:24:54 +02:00
ia64-acpi-cpufreq.c cpufreq: use kzalloc() to allocate memory for cpufreq_frequency_table 2014-04-07 14:43:49 +02:00
imx6q-cpufreq.c Driver core patches for 3.19-rc1 2014-12-14 16:10:09 -08:00
integrator-cpufreq.c cpufreq: drop owner assignment from platform_drivers 2014-10-20 16:20:24 +02:00
intel_pstate.c intel_pstate: Add get_scaling cpu_defaults param to Knights Landing 2015-07-27 01:59:43 +02:00
Kconfig cpufreq: qoriq: rename the driver 2015-03-18 22:35:16 +01:00
Kconfig.arm The changes to the common clock framework for 4.2 are dominated by new 2015-07-01 19:22:00 -07:00
Kconfig.powerpc cpufreq: qoriq: rename the driver 2015-03-18 22:35:16 +01:00
Kconfig.x86 cpufreq: Add SFI based cpufreq driver support 2014-12-20 13:37:37 -05:00
kirkwood-cpufreq.c cpufreq: drop owner assignment from platform_drivers 2014-10-20 16:20:24 +02:00
longhaul.c Update/Remove soon-to-be-dead email address 2014-12-19 12:56:15 -08:00
longhaul.h cpufreq: delete __cpuinit usage from all cpufreq files 2013-07-14 19:36:57 -04:00
longrun.c cpufreq: add new routine cpufreq_verify_within_cpu_limits() 2013-10-16 00:50:23 +02:00
loongson2_cpufreq.c MIPS, CPUFREQ: Fix spelling of Institute. 2015-07-07 20:59:42 +02:00
ls1x-cpufreq.c MIPS: Loongson: Naming style cleanup and rework 2015-06-21 21:53:59 +02:00
Makefile cpufreq: exynos: remove Exynos4210 specific cpufreq driver support 2015-06-20 12:17:44 -07:00
maple-cpufreq.c cpufreq: create another field .flags in cpufreq_frequency_table 2014-04-07 14:43:50 +02:00
omap-cpufreq.c cpufreq: drop owner assignment from platform_drivers 2014-10-20 16:20:24 +02:00
p4-clockmod.c p4-clockmod: Replace cpu_sibling_mask() with topology_sibling_cpumask() 2015-05-27 15:22:16 +02:00
pasemi-cpufreq.c cpufreq: Use cpufreq_for_each_* macros for frequency table iteration 2014-04-30 00:06:21 +02:00
pcc-cpufreq.c cpufreq: pcc: Enable autoload of pcc-cpufreq for ACPI processors 2014-11-14 00:16:25 +01:00
pmac32-cpufreq.c powerpc: Remove powerpc specific cmd_line 2014-10-02 17:33:55 +10:00
pmac64-cpufreq.c of: Migrate of_find_node_by_name() users to for_each_node_by_name() 2014-06-26 17:12:24 +01:00
powernow-k6.c Update/Remove soon-to-be-dead email address 2014-12-19 12:56:15 -08:00
powernow-k7.c Update/Remove soon-to-be-dead email address 2014-12-19 12:56:15 -08:00
powernow-k7.h
powernow-k8.c powernow-k8: Replace cpu_core_mask() with topology_core_cpumask() 2015-05-27 15:22:16 +02:00
powernow-k8.h cpufreq: powernow-k8: Suppress checkpatch warnings 2014-05-17 01:27:01 +02:00
powernv-cpufreq.c cpufreq: powernv: Report cpu frequency throttling 2015-04-01 23:02:24 +02:00
ppc_cbe_cpufreq_pervasive.c cpufreq: powerpc/platforms/cell: move cpufreq driver to drivers/cpufreq 2013-04-10 13:19:26 +02:00
ppc_cbe_cpufreq_pmi.c cpufreq: powerpc/platforms/cell: move cpufreq driver to drivers/cpufreq 2013-04-10 13:19:26 +02:00
ppc_cbe_cpufreq.c cpufreq: Use cpufreq_for_each_* macros for frequency table iteration 2014-04-30 00:06:21 +02:00
ppc_cbe_cpufreq.h cpufreq: powerpc/platforms/cell: move cpufreq driver to drivers/cpufreq 2013-04-10 13:19:26 +02:00
pxa2xx-cpufreq.c cpufreq: pxa: make pxa_freqs arrays const 2015-05-05 00:49:38 +02:00
pxa3xx-cpufreq.c cpufreq: Remove cpufreq_generic_exit() 2014-03-12 01:06:00 +01:00
qoriq-cpufreq.c cpufreq: qoriq: optimize the CPU frequency switching time 2015-06-15 15:47:28 +02:00
s3c24xx-cpufreq-debugfs.c cpufreq: s3c24xx: move cpufreq driver to drivers/cpufreq 2013-05-20 23:04:28 +09:00
s3c24xx-cpufreq.c cpufreq: s3c: remove last use of resume_clocks callback 2015-02-19 06:36:53 +01:00
s3c64xx-cpufreq.c cpufreq: Use cpufreq_for_each_* macros for frequency table iteration 2014-04-30 00:06:21 +02:00
s3c2410-cpufreq.c cpufreq: s3c24xx: Remove some dead code 2014-07-19 04:24:59 +09:00
s3c2412-cpufreq.c cpufreq: s3c24xx: Remove some dead code 2014-07-19 04:24:59 +09:00
s3c2416-cpufreq.c cpufreq: s3c: remove incorrect __init annotations 2015-02-19 06:36:53 +01:00
s3c2440-cpufreq.c cpufreq: s3c24xx: Remove some dead code 2014-07-19 04:24:59 +09:00
s5pv210-cpufreq.c drivers/cpufreq: Convert non-modular s5pv210-cpufreq.c to use builtin_platform_driver 2015-06-16 14:12:38 -04:00
sa1100-cpufreq.c cpufreq: Mark ARM drivers with CPUFREQ_NEED_INITIAL_FREQ_CHECK flag 2014-01-06 14:17:25 +01:00
sa1110-cpufreq.c cpufreq: sa1110: set memory type for h3600 2014-07-16 14:30:17 +02:00
sc520_freq.c cpufreq: create another field .flags in cpufreq_frequency_table 2014-04-07 14:43:50 +02:00
sfi-cpufreq.c cpufreq: Add SFI based cpufreq driver support 2014-12-20 13:37:37 -05:00
sh-cpufreq.c cpufreq: Convert existing drivers to use cpufreq_freq_transition_{begin|end} 2014-03-26 16:41:41 +01:00
sparc-us2e-cpufreq.c cpufreq: add 'freq_table' in struct cpufreq_policy 2014-03-12 01:06:00 +01:00
sparc-us3-cpufreq.c cpufreq: add 'freq_table' in struct cpufreq_policy 2014-03-12 01:06:00 +01:00
spear-cpufreq.c cpufreq: drop owner assignment from platform_drivers 2014-10-20 16:20:24 +02:00
speedstep-centrino.c cpufreq: Make linux-pm@vger.kernel.org official mailing list 2014-05-01 01:15:32 +02:00
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-smi: enable interrupts when waiting 2015-02-12 02:02:52 +01:00
speedstep-lib.h
speedstep-smi.c cpufreq: speedstep-smi: enable interrupts when waiting 2015-02-12 02:02:52 +01:00
tegra-cpufreq.c cpufreq: tegra: update comment for clarity 2014-06-10 22:50:50 +02:00
unicore2-cpufreq.c cpufreq: unicore32: replace IS_ERR and PTR_ERR with PTR_ERR_OR_ZERO 2014-04-21 23:42:27 +02:00
vexpress-spc-cpufreq.c cpufreq: drop owner assignment from platform_drivers 2014-10-20 16:20:24 +02:00