kernel/watchdog.c: avoid races between /proc handlers and CPU hotplug

[firefly-linux-kernel-4.4.55.git] / kernel / watchdog.c

diff --git a/kernel/watchdog.c b/kernel/watchdog.c
index 7357842da933aac3afb498116c42a529d02aa4b9..13fdda1a4c91b52e14076026304b4188b49a4ad7 100644 (file)
--- a/kernel/watchdog.c
+++ b/kernel/watchdog.c
@@ -857,6 +857,7 @@ static int proc_watchdog_common(int which, struct ctl_table *table, int write,
        int err, old, new;
        int *watchdog_param = (int *)table->data;
 
+       get_online_cpus();
        mutex_lock(&watchdog_proc_mutex);
 
        if (watchdog_suspended) {
@@ -908,6 +909,7 @@ static int proc_watchdog_common(int which, struct ctl_table *table, int write,
        }
 out:
        mutex_unlock(&watchdog_proc_mutex);
+       put_online_cpus();
        return err;
 }
 
@@ -949,6 +951,7 @@ int proc_watchdog_thresh(struct ctl_table *table, int write,
 {
        int err, old;
 
+       get_online_cpus();
        mutex_lock(&watchdog_proc_mutex);
 
        if (watchdog_suspended) {
@@ -974,6 +977,7 @@ int proc_watchdog_thresh(struct ctl_table *table, int write,
        }
 out:
        mutex_unlock(&watchdog_proc_mutex);
+       put_online_cpus();
        return err;
 }
 
@@ -988,6 +992,7 @@ int proc_watchdog_cpumask(struct ctl_table *table, int write,
 {
        int err;
 
+       get_online_cpus();
        mutex_lock(&watchdog_proc_mutex);
 
        if (watchdog_suspended) {
@@ -1015,6 +1020,7 @@ int proc_watchdog_cpumask(struct ctl_table *table, int write,
        }
 out:
        mutex_unlock(&watchdog_proc_mutex);
+       put_online_cpus();
        return err;
 }