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Groups > linux.kernel > #1257022
| From | Bálint Czobor <czoborbalint@gmail.com> |
|---|---|
| Newsgroups | linux.kernel |
| Subject | [PATCH 35/70] cpufreq: interactive: fix racy timer stopping |
| Date | 2015-10-27 18:40 +0100 |
| Message-ID | <qogo4-84h-89@gated-at.bofh.it> (permalink) |
| References | <qogo1-84h-5@gated-at.bofh.it> |
| Organization | linux.* mail to news gateway |
From: Todd Poynor <toddpoynor@google.com>
When stopping the governor, del_timer_sync() can race against an
invocation of the idle notifier callback, which has the potential
to reactivate the timer.
To fix this issue, a read-write semaphore is used. Multiple readers are
allowed as long as pcpu->governor_enabled is true. However it can be
moved to false only after taking a write semaphore which would wait for
any on-going asynchronous activities to complete and prevent any more of
those activities to be initiated.
[toddpoynor@google.com: cosmetic and commit text changes]
Change-Id: Ib51165a735d73dcf964a06754c48bdc1913e13d0
Signed-off-by: Nicolas Pitre <nicolas.pitre@linaro.org>
Signed-off-by: Bálint Czobor <czoborbalint@gmail.com>
---
drivers/cpufreq/cpufreq_interactive.c | 38 ++++++++++++++++++++++++---------
1 file changed, 28 insertions(+), 10 deletions(-)
diff --git a/drivers/cpufreq/cpufreq_interactive.c b/drivers/cpufreq/cpufreq_interactive.c
index f8e9ee9..74f5609 100644
--- a/drivers/cpufreq/cpufreq_interactive.c
+++ b/drivers/cpufreq/cpufreq_interactive.c
@@ -21,7 +21,7 @@
#include <linux/cpufreq.h>
#include <linux/module.h>
#include <linux/moduleparam.h>
-#include <linux/mutex.h>
+#include <linux/rwsem.h>
#include <linux/sched.h>
#include <linux/sched/rt.h>
#include <linux/tick.h>
@@ -29,7 +29,6 @@
#include <linux/timer.h>
#include <linux/workqueue.h>
#include <linux/kthread.h>
-#include <linux/mutex.h>
#include <linux/slab.h>
#include <asm/cputime.h>
@@ -52,6 +51,7 @@ struct cpufreq_interactive_cpuinfo {
unsigned int floor_freq;
u64 floor_validate_time;
u64 hispeed_validate_time;
+ struct rw_semaphore enable_sem;
int governor_enabled;
};
@@ -279,8 +279,8 @@ static void cpufreq_interactive_timer(unsigned long data)
unsigned long flags;
bool boosted;
- smp_rmb();
-
+ if (!down_read_trylock(&pcpu->enable_sem))
+ return;
if (!pcpu->governor_enabled)
goto exit;
@@ -387,6 +387,7 @@ rearm:
cpufreq_interactive_timer_resched(pcpu);
exit:
+ up_read(&pcpu->enable_sem);
return;
}
@@ -396,8 +397,12 @@ static void cpufreq_interactive_idle_start(void)
&per_cpu(cpuinfo, smp_processor_id());
int pending;
- if (!pcpu->governor_enabled)
+ if (!down_read_trylock(&pcpu->enable_sem))
+ return;
+ if (!pcpu->governor_enabled) {
+ up_read(&pcpu->enable_sem);
return;
+ }
pending = timer_pending(&pcpu->cpu_timer);
@@ -414,6 +419,7 @@ static void cpufreq_interactive_idle_start(void)
cpufreq_interactive_timer_resched(pcpu);
}
+ up_read(&pcpu->enable_sem);
}
static void cpufreq_interactive_idle_end(void)
@@ -421,8 +427,12 @@ static void cpufreq_interactive_idle_end(void)
struct cpufreq_interactive_cpuinfo *pcpu =
&per_cpu(cpuinfo, smp_processor_id());
- if (!pcpu->governor_enabled)
+ if (!down_read_trylock(&pcpu->enable_sem))
+ return;
+ if (!pcpu->governor_enabled) {
+ up_read(&pcpu->enable_sem);
return;
+ }
/* Arm the timer for 1-2 ticks later if not already. */
if (!timer_pending(&pcpu->cpu_timer)) {
@@ -432,6 +442,8 @@ static void cpufreq_interactive_idle_end(void)
del_timer(&pcpu->cpu_slack_timer);
cpufreq_interactive_timer(smp_processor_id());
}
+
+ up_read(&pcpu->enable_sem);
}
static int cpufreq_interactive_speedchange_task(void *data)
@@ -466,10 +478,12 @@ static int cpufreq_interactive_speedchange_task(void *data)
unsigned int max_freq = 0;
pcpu = &per_cpu(cpuinfo, cpu);
- smp_rmb();
-
- if (!pcpu->governor_enabled)
+ if (!down_read_trylock(&pcpu->enable_sem))
+ continue;
+ if (!pcpu->governor_enabled) {
+ up_read(&pcpu->enable_sem);
continue;
+ }
for_each_cpu(j, pcpu->policy->cpus) {
struct cpufreq_interactive_cpuinfo *pjcpu =
@@ -486,6 +500,8 @@ static int cpufreq_interactive_speedchange_task(void *data)
trace_cpufreq_interactive_setspeed(cpu,
pcpu->target_freq,
pcpu->policy->cur);
+
+ up_read(&pcpu->enable_sem);
}
}
@@ -936,10 +952,11 @@ static int cpufreq_governor_interactive(struct cpufreq_policy *policy,
case CPUFREQ_GOV_STOP:
for_each_cpu(j, policy->cpus) {
pcpu = &per_cpu(cpuinfo, j);
+ down_write(&pcpu->enable_sem);
pcpu->governor_enabled = 0;
- smp_wmb();
del_timer_sync(&pcpu->cpu_timer);
del_timer_sync(&pcpu->cpu_slack_timer);
+ up_write(&pcpu->enable_sem);
}
if (atomic_dec_return(&active_count) > 0)
@@ -989,6 +1006,7 @@ static int __init cpufreq_interactive_init(void)
init_timer(&pcpu->cpu_slack_timer);
pcpu->cpu_slack_timer.function = cpufreq_interactive_nop_timer;
spin_lock_init(&pcpu->load_lock);
+ init_rwsem(&pcpu->enable_sem);
}
spin_lock_init(&target_loads_lock);
--
1.7.9.5
--
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[PATCH 01/70] cpufreq: interactive: New 'interactive' governor Bálint Czobor <czoborbalint@gmail.com> - 2015-10-27 18:40 +0100
[PATCH 57/70] cpufreq: interactive: fix compiling warnings Bálint Czobor <czoborbalint@gmail.com> - 2015-10-27 18:40 +0100
[PATCH 56/70] cpufreq: interactive: delete timers for GOV_START Bálint Czobor <czoborbalint@gmail.com> - 2015-10-27 18:40 +0100
[PATCH 41/70] cpufreq: interactive: fix race on governor start/stop Bálint Czobor <czoborbalint@gmail.com> - 2015-10-27 18:40 +0100
[PATCH 32/70] cpufreq: interactive: specify duration of CPU speed boost pulse Bálint Czobor <czoborbalint@gmail.com> - 2015-10-27 18:40 +0100
[PATCH 43/70] cpufreq: interactive: add io_is_busy interface Bálint Czobor <czoborbalint@gmail.com> - 2015-10-27 18:40 +0100
[PATCH 39/70] cpufreq: interactive: don't handle transition notification if not enabled Bálint Czobor <czoborbalint@gmail.com> - 2015-10-27 18:40 +0100
[PATCH 51/70] cpufreq: interactive: resched timer if max freq raised Bálint Czobor <czoborbalint@gmail.com> - 2015-10-27 18:40 +0100
[PATCH 09/70] cpufreq: interactive: Separate speed target revalidate time and initial set time Bálint Czobor <czoborbalint@gmail.com> - 2015-10-27 18:40 +0100
[PATCH 60/70] cpufreq: interactive: hold reference on global cpufreq kobject if needed Bálint Czobor <czoborbalint@gmail.com> - 2015-10-27 18:40 +0100
[PATCH 24/70] cpufreq: interactive: use deferrable timer by default Bálint Czobor <czoborbalint@gmail.com> - 2015-10-27 18:40 +0100
[PATCH 61/70] cpufreq: interactive: restructure CPUFREQ_GOV_LIMITS Bálint Czobor <czoborbalint@gmail.com> - 2015-10-27 18:40 +0100
[PATCH 27/70] cpufreq: interactive: change speed according to current speed and target load Bálint Czobor <czoborbalint@gmail.com> - 2015-10-27 18:40 +0100
[PATCH 07/70] cpufreq: interactive: adjust code and documentation to match Bálint Czobor <czoborbalint@gmail.com> - 2015-10-27 18:40 +0100
[PATCH 29/70] cpufreq: interactive: allow arbitrary speed / target load mappings Bálint Czobor <czoborbalint@gmail.com> - 2015-10-27 18:40 +0100
[PATCH 48/70] cpufreq: interactive: reduce chance of zero time delta on load eval Bálint Czobor <czoborbalint@gmail.com> - 2015-10-27 18:40 +0100
[PATCH 64/70] cpufreq: interactive: prevents the frequency to directly raise above the hispeed_freq from a lower frequency. Bálint Czobor <czoborbalint@gmail.com> - 2015-10-27 18:40 +0100
[PATCH 65/70] cpufreq: interactive: make common_tunables static Bálint Czobor <czoborbalint@gmail.com> - 2015-10-27 18:40 +0100
[PATCH 69/70] cpufreq: interactive: Don't set floor_validate_time during boost Bálint Czobor <czoborbalint@gmail.com> - 2015-10-27 18:40 +0100
[PATCH 37/70] cpufreq: interactive: default go_hispeed_load 99%, doc updates Bálint Czobor <czoborbalint@gmail.com> - 2015-10-27 18:40 +0100
[PATCH 58/70] cpufreq: interactive: fix NULL pointer dereference at sysfs ops Bálint Czobor <czoborbalint@gmail.com> - 2015-10-27 18:40 +0100
[PATCH 66/70] cpufreq: interactive: Fix compile errors in accordance with changes from 3.14 to 3.18 Bálint Czobor <czoborbalint@gmail.com> - 2015-10-27 18:40 +0100
[PATCH 17/70] cpufreq: interactive: take idle notifications only when active Bálint Czobor <czoborbalint@gmail.com> - 2015-10-27 18:40 +0100
[PATCH 35/70] cpufreq: interactive: fix racy timer stopping Bálint Czobor <czoborbalint@gmail.com> - 2015-10-27 18:40 +0100
[PATCH 67/70] cpufreq: interactive: Put global cpufreq kobject on failure Bálint Czobor <czoborbalint@gmail.com> - 2015-10-27 18:40 +0100
[PATCH 70/70] cpufreq: interactive: Round up timer_rate to match jiffy Bálint Czobor <czoborbalint@gmail.com> - 2015-10-27 18:40 +0100
[PATCH 20/70] cpufreq: interactive: remove input_boost handling Bálint Czobor <czoborbalint@gmail.com> - 2015-10-27 18:40 +0100
[PATCH 12/70] cpufreq: interactive: Add sysfs boost interface for hints from userspace Bálint Czobor <czoborbalint@gmail.com> - 2015-10-27 18:40 +0100
[PATCH 22/70] cpufreq: interactive: run at fraction of hispeed_freq when load is low Bálint Czobor <czoborbalint@gmail.com> - 2015-10-27 18:40 +0100
[PATCH 68/70] subsystem: CPU FREQUENCY DRIVERS- Set cpu_load calculation on current frequency Bálint Czobor <czoborbalint@gmail.com> - 2015-10-27 18:40 +0100
[PATCH 13/70] cpufreq: interactive: set floor for boosted speed Bálint Czobor <czoborbalint@gmail.com> - 2015-10-27 18:40 +0100
[PATCH 55/70] cpufreq: Interactive: Implement per policy instances of governor Bálint Czobor <czoborbalint@gmail.com> - 2015-10-27 18:40 +0100
[PATCH 52/70] cpufreq: interactive: fix show_target_loads and show_above_hispeed_delay Bálint Czobor <czoborbalint@gmail.com> - 2015-10-27 18:40 +0100
[PATCH 10/70] cpufreq: interactive: Boost frequency on touchscreen input Bálint Czobor <czoborbalint@gmail.com> - 2015-10-27 18:40 +0100
[PATCH 62/70] cpufreq: interactive: turn boost_pulse off on boost off Bálint Czobor <czoborbalint@gmail.com> - 2015-10-27 18:50 +0100
[PATCH 59/70] cpufreq: interactive: Use generic get_cpu_idle_time() from cpufreq.c Bálint Czobor <czoborbalint@gmail.com> - 2015-10-27 18:50 +0100
[PATCH 54/70] cpufreq: interactive: Move definition of cpufreq_gov_interactive downwards Bálint Czobor <czoborbalint@gmail.com> - 2015-10-27 18:50 +0100
[PATCH 53/70] cpufreq: interactive: Remove unnecessary cpu_online() check Bálint Czobor <czoborbalint@gmail.com> - 2015-10-27 18:50 +0100
[PATCH 25/70] cpufreq: interactive: kick timer on idle exit past expiry Bálint Czobor <czoborbalint@gmail.com> - 2015-10-27 18:50 +0100
[PATCH 47/70] cpufreq: interactive: handle errors from cpufreq_frequency_table_target Bálint Czobor <czoborbalint@gmail.com> - 2015-10-27 18:50 +0100
[PATCH 63/70] cpufreq: interactive: remove compilation error from commit 49cc72365fb7ee87762a7ccc6a32ef68627216c5 Bálint Czobor <czoborbalint@gmail.com> - 2015-10-27 18:50 +0100
[PATCH 44/70] cpufreq: interactive: fix crash on error paths in get_tokenized_data Bálint Czobor <czoborbalint@gmail.com> - 2015-10-27 18:50 +0100
[PATCH 50/70] cpufreq: interactive: fix race on cpufreq TRANSITION notifier Bálint Czobor <czoborbalint@gmail.com> - 2015-10-27 18:50 +0100
[PATCH 49/70] cpufreq: interactive: avoid underflow on active time calculation Bálint Czobor <czoborbalint@gmail.com> - 2015-10-27 18:50 +0100
[PATCH 45/70] cpufreq: interactive: base above_hispeed_delay on target freq, not current Bálint Czobor <czoborbalint@gmail.com> - 2015-10-27 18:50 +0100
[PATCH 46/70] cpufreq: interactive: fix uninitialized spinlock Bálint Czobor <czoborbalint@gmail.com> - 2015-10-27 18:50 +0100
[PATCH 34/70] cpufreq: interactive: fix boosting logic Bálint Czobor <czoborbalint@gmail.com> - 2015-10-27 19:00 +0100
[PATCH 38/70] cpufreq: interactive: init default values at compile time Bálint Czobor <czoborbalint@gmail.com> - 2015-10-27 19:00 +0100
[PATCH 16/70] cpufreq: interactive: restart above_hispeed_delay at each hispeed load Bálint Czobor <czoborbalint@gmail.com> - 2015-10-27 19:00 +0100
[PATCH 28/70] cpufreq: interactive: apply above_hispeed_delay to each step above hispeed Bálint Czobor <czoborbalint@gmail.com> - 2015-10-27 19:00 +0100
[PATCH 23/70] cpufreq: interactive: pin timers to associated CPU Bálint Czobor <czoborbalint@gmail.com> - 2015-10-27 19:00 +0100
[PATCH 18/70] cpufreq: interactive: keep freezer happy when not current governor Bálint Czobor <czoborbalint@gmail.com> - 2015-10-27 19:00 +0100
[PATCH 21/70] cpufreq: interactive: always limit initial speed bump to hispeed Bálint Czobor <czoborbalint@gmail.com> - 2015-10-27 19:00 +0100
[PATCH 36/70] cpufreq: interactive: fix race on timer restart on governor start Bálint Czobor <czoborbalint@gmail.com> - 2015-10-27 19:00 +0100
[PATCH 19/70] cpufreq: interactive: handle speed up and down in the realtime task Bálint Czobor <czoborbalint@gmail.com> - 2015-10-27 19:00 +0100
[PATCH 42/70] cpufreq: interactive: allow arbitrary speed / delay mappings Bálint Czobor <czoborbalint@gmail.com> - 2015-10-27 19:00 +0100
[PATCH 26/70] cpufreq: interactive: trace actual speed in target speed decisions Bálint Czobor <czoborbalint@gmail.com> - 2015-10-27 19:00 +0100
[PATCH 30/70] cpufreq: interactive: remove load since last speed change Bálint Czobor <czoborbalint@gmail.com> - 2015-10-27 19:00 +0100
[PATCH 40/70] cpufreq: interactive: fix deadlock on spinlock in timer Bálint Czobor <czoborbalint@gmail.com> - 2015-10-27 19:00 +0100
[PATCH 33/70] cpufreq: interactive: add timer slack to limit idle at speed > min Bálint Czobor <czoborbalint@gmail.com> - 2015-10-27 19:00 +0100
[PATCH 31/70] cpufreq: interactive: adjust load for changes in speed Bálint Czobor <czoborbalint@gmail.com> - 2015-10-27 19:00 +0100
[PATCH 04/70] cpufreq: interactive: set at least hispeed when above hispeed load Bálint Czobor <czoborbalint@gmail.com> - 2015-10-27 19:10 +0100
[PATCH 02/70] cpufreq interactive governor: event tracing Bálint Czobor <czoborbalint@gmail.com> - 2015-10-27 19:10 +0100
[PATCH 11/70] cpufreq: interactive: remove unused target_validate_time_in_idle Bálint Czobor <czoborbalint@gmail.com> - 2015-10-27 19:10 +0100
[PATCH 05/70] cpufreq: interactive: don't drop speed if recently at higher load Bálint Czobor <czoborbalint@gmail.com> - 2015-10-27 19:10 +0100
[PATCH 06/70] cpufreq: interactive: configurable delay before raising above hispeed Bálint Czobor <czoborbalint@gmail.com> - 2015-10-27 19:10 +0100
[PATCH 08/70] cpufreq: interactive: base hispeed bump on target freq, not actual Bálint Czobor <czoborbalint@gmail.com> - 2015-10-27 19:10 +0100
[PATCH 15/70] cpufreq-interactive: Compile fixup Bálint Czobor <czoborbalint@gmail.com> - 2015-10-27 19:10 +0100
[PATCH 14/70] cpufreq: interactive: add boost pulse interface Bálint Czobor <czoborbalint@gmail.com> - 2015-10-27 19:10 +0100
Re: [PATCH 01/70] cpufreq: interactive: New 'interactive' governor "Rafael J. Wysocki" <rjw@rjwysocki.net> - 2015-10-28 01:40 +0100
Re: [PATCH 01/70] cpufreq: interactive: New 'interactive' governor Viresh Kumar <viresh.kumar@linaro.org> - 2015-10-28 04:10 +0100
Re: [PATCH 01/70] cpufreq: interactive: New 'interactive' governor Viresh Kumar <viresh.kumar@linaro.org> - 2015-10-29 02:50 +0100
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