* [PATCH] Revert "cpufreq: Fix possible race in cpufreq online error path"
@ 2022-05-09 3:57 Viresh Kumar
2022-05-09 17:08 ` Rafael J. Wysocki
0 siblings, 1 reply; 2+ messages in thread
From: Viresh Kumar @ 2022-05-09 3:57 UTC (permalink / raw)
To: Rafael Wysocki, Rafael J. Wysocki, Viresh Kumar, Schspa Shi
Cc: linux-pm, Vincent Guittot, Rafael J. Wysocki, linux-kernel
This reverts commit f346e96267cd76175d6c201b40f770c0116a8a04.
The commit tried to fix a possible real bug but it made it even worse.
The fix was simply buggy as now an error out to out_offline_policy or
out_exit_policy will try to release a semaphore which was never taken in
the first place. This works fine only if we failed late, i.e. via
out_destroy_policy.
Fixes: f346e96267cd ("cpufreq: Fix possible race in cpufreq online error path")
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
---
drivers/cpufreq/cpufreq.c | 5 ++---
1 file changed, 2 insertions(+), 3 deletions(-)
diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
index 233e8af48848..fbaa8e6c7d23 100644
--- a/drivers/cpufreq/cpufreq.c
+++ b/drivers/cpufreq/cpufreq.c
@@ -1534,6 +1534,8 @@ static int cpufreq_online(unsigned int cpu)
for_each_cpu(j, policy->real_cpus)
remove_cpu_dev_symlink(policy, get_cpu_device(j));
+ up_write(&policy->rwsem);
+
out_offline_policy:
if (cpufreq_driver->offline)
cpufreq_driver->offline(policy);
@@ -1542,9 +1544,6 @@ static int cpufreq_online(unsigned int cpu)
if (cpufreq_driver->exit)
cpufreq_driver->exit(policy);
- cpumask_clear(policy->cpus);
- up_write(&policy->rwsem);
-
out_free_policy:
cpufreq_policy_free(policy);
return ret;
--
2.31.1.272.g89b43f80a514
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH] Revert "cpufreq: Fix possible race in cpufreq online error path"
2022-05-09 3:57 [PATCH] Revert "cpufreq: Fix possible race in cpufreq online error path" Viresh Kumar
@ 2022-05-09 17:08 ` Rafael J. Wysocki
0 siblings, 0 replies; 2+ messages in thread
From: Rafael J. Wysocki @ 2022-05-09 17:08 UTC (permalink / raw)
To: Viresh Kumar
Cc: Rafael Wysocki, Rafael J. Wysocki, Schspa Shi, Linux PM,
Vincent Guittot, Rafael J. Wysocki, Linux Kernel Mailing List
On Mon, May 9, 2022 at 5:57 AM Viresh Kumar <viresh.kumar@linaro.org> wrote:
>
> This reverts commit f346e96267cd76175d6c201b40f770c0116a8a04.
>
> The commit tried to fix a possible real bug but it made it even worse.
> The fix was simply buggy as now an error out to out_offline_policy or
> out_exit_policy will try to release a semaphore which was never taken in
> the first place. This works fine only if we failed late, i.e. via
> out_destroy_policy.
>
> Fixes: f346e96267cd ("cpufreq: Fix possible race in cpufreq online error path")
> Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Applied, thanks!
I should have caught the breakage in this patch, sorry about missing it.
> ---
> drivers/cpufreq/cpufreq.c | 5 ++---
> 1 file changed, 2 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
> index 233e8af48848..fbaa8e6c7d23 100644
> --- a/drivers/cpufreq/cpufreq.c
> +++ b/drivers/cpufreq/cpufreq.c
> @@ -1534,6 +1534,8 @@ static int cpufreq_online(unsigned int cpu)
> for_each_cpu(j, policy->real_cpus)
> remove_cpu_dev_symlink(policy, get_cpu_device(j));
>
> + up_write(&policy->rwsem);
> +
> out_offline_policy:
> if (cpufreq_driver->offline)
> cpufreq_driver->offline(policy);
> @@ -1542,9 +1544,6 @@ static int cpufreq_online(unsigned int cpu)
> if (cpufreq_driver->exit)
> cpufreq_driver->exit(policy);
>
> - cpumask_clear(policy->cpus);
> - up_write(&policy->rwsem);
> -
> out_free_policy:
> cpufreq_policy_free(policy);
> return ret;
> --
> 2.31.1.272.g89b43f80a514
>
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2022-05-09 17:08 ` Rafael J. Wysocki
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