[PATCH v2] timer/sysclt: Restrict timer migration sysctl values to 0 and 1

[Myungho Jung <mhjungk@gmail.com>]

timer_migration sysctl acts as a boolean switch, so the allowed values
should be restricted to 0 and 1.

Add the necessary extra fields to the sysctl table entry to enforce
that.

Testcase is ltp/runpwtests06.

Signed-off-by: Myungho Jung <mhjungk@gmail.com>
---
Changes in v2:
 - Correct commit log

 kernel/sysctl.c     | 2 ++
 kernel/time/timer.c | 2 +-
 2 files changed, 3 insertions(+), 1 deletion(-)

diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index 8c8714f..21343d1 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -1176,6 +1176,8 @@ static struct ctl_table kern_table[] = {
 		.maxlen		= sizeof(unsigned int),
 		.mode		= 0644,
 		.proc_handler	= timer_migration_handler,
+		.extra1		= &zero,
+		.extra2		= &one,
 	},
 #endif
 #ifdef CONFIG_BPF_SYSCALL
diff --git a/kernel/time/timer.c b/kernel/time/timer.c
index 1dc0256..cc6b6bd 100644
--- a/kernel/time/timer.c
+++ b/kernel/time/timer.c
@@ -241,7 +241,7 @@ int timer_migration_handler(struct ctl_table *table, int write,
 	int ret;
 
 	mutex_lock(&mutex);
-	ret = proc_dointvec(table, write, buffer, lenp, ppos);
+	ret = proc_dointvec_minmax(table, write, buffer, lenp, ppos);
 	if (!ret && write)
 		timers_update_migration(false);
 	mutex_unlock(&mutex);
-- 
2.7.4