linux-kernel - [PATCH v7 6/7] cgroup/cpuset: Use cpuset_mutex to protect seq

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Date:   Wed,  3 Apr 2019 10:46:49 +0200
From:   Juri Lelli <juri.lelli@...hat.com>
To:     peterz@...radead.org, mingo@...hat.com, rostedt@...dmis.org,
        tj@...nel.org
Cc:     linux-kernel@...r.kernel.org, luca.abeni@...tannapisa.it,
        claudio@...dence.eu.com, tommaso.cucinotta@...tannapisa.it,
        bristot@...hat.com, mathieu.poirier@...aro.org, lizefan@...wei.com,
        cgroups@...r.kernel.org, Juri Lelli <juri.lelli@...hat.com>
Subject: [PATCH v7 6/7] cgroup/cpuset: Use cpuset_mutex to protect seq_show operations

cpuset_common_seq_show operations atomicity is currently guarded by
callback_lock. Since these operations are initiated by userspace holding
a raw_spin_lock is not wise.

Convert the function to use cpuset_mutex to fix the problem.

Signed-off-by: Juri Lelli <juri.lelli@...hat.com>
---
 kernel/cgroup/cpuset.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/kernel/cgroup/cpuset.c b/kernel/cgroup/cpuset.c
index cb5ff6ca5d2c..91ef48bbc08d 100644
--- a/kernel/cgroup/cpuset.c
+++ b/kernel/cgroup/cpuset.c
@@ -2444,7 +2444,7 @@ static int cpuset_common_seq_show(struct seq_file *sf, void *v)
 	cpuset_filetype_t type = seq_cft(sf)->private;
 	int ret = 0;
 
-	raw_spin_lock_irq(&callback_lock);
+	mutex_lock(&cpuset_mutex);
 
 	switch (type) {
 	case FILE_CPULIST:
@@ -2466,7 +2466,7 @@ static int cpuset_common_seq_show(struct seq_file *sf, void *v)
 		ret = -EINVAL;
 	}
 
-	raw_spin_unlock_irq(&callback_lock);
+	mutex_unlock(&cpuset_mutex);
 	return ret;
 }
 
-- 
2.17.2