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alarm : Fix the race conditions in alarm-dev.c

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There will be race conditions between alarm set and alarm clear if
set_power_on_alarm is out of the lock.But set_power_on_alarm can't
be put into spin_lock. So add it into mutex_lock.

CRs-Fixed: 639115
Change-Id: I1db4836f67174b756c7f9d231f7a39cf0377d2c2
Signed-off-by: Xiaocheng Li <lix@codeaurora.org>
This commit is contained in:
Xiaocheng Li
2014-04-28 23:26:21 -07:00
committed by Gerrit - the friendly Code Review server
parent eeb31ff78d
commit 446d682932
1 changed files with 5 additions and 0 deletions
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drivers/rtc/alarm-dev.c
+5
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@@ -49,6 +49,7 @@ module_param_named(debug_mask, debug_mask, int, S_IRUGO | S_IWUSR | S_IWGRP);
#define ANDROID_ALARM_SET_AND_WAIT_OLD _IOW('a', 3, time_t)
static int alarm_opened;
static DEFINE_MUTEX(alarm_mutex);
static DEFINE_SPINLOCK(alarm_slock);
static struct wake_lock alarm_wake_lock;
static DECLARE_WAIT_QUEUE_HEAD(alarm_wait_queue);
@@ -89,6 +90,7 @@ static long alarm_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
switch (ANDROID_ALARM_BASE_CMD(cmd)) {
case ANDROID_ALARM_CLEAR(0):
mutex_lock(&alarm_mutex);
spin_lock_irqsave(&alarm_slock, flags);
pr_alarm(IO, "alarm %d clear\n", alarm_type);
alarm_try_to_cancel(&alarms[alarm_type]);
@@ -103,6 +105,7 @@ static long alarm_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
if (!copy_from_user(&new_alarm_time,
(void __user *)arg, sizeof(new_alarm_time)))
set_power_on_alarm(new_alarm_time.tv_sec, 0);
mutex_unlock(&alarm_mutex);
break;
case ANDROID_ALARM_SET_OLD:
@@ -122,6 +125,7 @@ static long alarm_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
goto err1;
}
from_old_alarm_set:
mutex_lock(&alarm_mutex);
spin_lock_irqsave(&alarm_slock, flags);
pr_alarm(IO, "alarm %d set %ld.%09ld\n", alarm_type,
new_alarm_time.tv_sec, new_alarm_time.tv_nsec);
@@ -134,6 +138,7 @@ from_old_alarm_set:
(ANDROID_ALARM_BASE_CMD(cmd) ==
ANDROID_ALARM_SET(0)))
set_power_on_alarm(new_alarm_time.tv_sec, 1);
mutex_unlock(&alarm_mutex);
if (ANDROID_ALARM_BASE_CMD(cmd) != ANDROID_ALARM_SET_AND_WAIT(0)
&& cmd != ANDROID_ALARM_SET_AND_WAIT_OLD)
break;