linux-kernel - [PATCH 5.10 198/452] Revert "cpufreq: Fix possible race in cpufreq online error path"

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Message-Id: <20220607164914.464475954@linuxfoundation.org>
Date:   Tue,  7 Jun 2022 19:00:55 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Viresh Kumar <viresh.kumar@...aro.org>,
        "Rafael J. Wysocki" <rafael.j.wysocki@...el.com>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 5.10 198/452] Revert "cpufreq: Fix possible race in cpufreq online error path"

From: Viresh Kumar <viresh.kumar@...aro.org>

[ Upstream commit 85f0e42bd65d01b351d561efb38e584d4c596553 ]

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@...aro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
Signed-off-by: Sasha Levin <sashal@...nel.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 3540ea93b6f1..30dafe8fc505 100644
--- a/drivers/cpufreq/cpufreq.c
+++ b/drivers/cpufreq/cpufreq.c
@@ -1515,6 +1515,8 @@ 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);
@@ -1523,9 +1525,6 @@ 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;
-- 
2.35.1