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-rw-r--r--kernel/kmod.c58
1 files changed, 45 insertions, 13 deletions
diff --git a/kernel/kmod.c b/kernel/kmod.c
index 4079ac1d5e79..da7fcca279f9 100644
--- a/kernel/kmod.c
+++ b/kernel/kmod.c
@@ -334,6 +334,12 @@ static atomic_t running_helpers = ATOMIC_INIT(0);
static DECLARE_WAIT_QUEUE_HEAD(running_helpers_waitq);
/*
+ * Used by usermodehelper_read_lock_wait() to wait for usermodehelper_disabled
+ * to become 'false'.
+ */
+static DECLARE_WAIT_QUEUE_HEAD(usermodehelper_disabled_waitq);
+
+/*
* Time to wait for running_helpers to become zero before the setting of
* usermodehelper_disabled in usermodehelper_disable() fails
*/
@@ -352,6 +358,33 @@ int usermodehelper_read_trylock(void)
}
EXPORT_SYMBOL_GPL(usermodehelper_read_trylock);
+long usermodehelper_read_lock_wait(long timeout)
+{
+ DEFINE_WAIT(wait);
+
+ if (timeout < 0)
+ return -EINVAL;
+
+ down_read(&umhelper_sem);
+ for (;;) {
+ prepare_to_wait(&usermodehelper_disabled_waitq, &wait,
+ TASK_UNINTERRUPTIBLE);
+ if (!usermodehelper_disabled)
+ break;
+
+ up_read(&umhelper_sem);
+
+ timeout = schedule_timeout(timeout);
+ if (!timeout)
+ break;
+
+ down_read(&umhelper_sem);
+ }
+ finish_wait(&usermodehelper_disabled_waitq, &wait);
+ return timeout;
+}
+EXPORT_SYMBOL_GPL(usermodehelper_read_lock_wait);
+
void usermodehelper_read_unlock(void)
{
up_read(&umhelper_sem);
@@ -359,6 +392,17 @@ void usermodehelper_read_unlock(void)
EXPORT_SYMBOL_GPL(usermodehelper_read_unlock);
/**
+ * usermodehelper_enable - allow new helpers to be started again
+ */
+void usermodehelper_enable(void)
+{
+ down_write(&umhelper_sem);
+ usermodehelper_disabled = 0;
+ wake_up(&usermodehelper_disabled_waitq);
+ up_write(&umhelper_sem);
+}
+
+/**
* usermodehelper_disable - prevent new helpers from being started
*/
int usermodehelper_disable(void)
@@ -381,22 +425,10 @@ int usermodehelper_disable(void)
if (retval)
return 0;
- down_write(&umhelper_sem);
- usermodehelper_disabled = 0;
- up_write(&umhelper_sem);
+ usermodehelper_enable();
return -EAGAIN;
}
-/**
- * usermodehelper_enable - allow new helpers to be started again
- */
-void usermodehelper_enable(void)
-{
- down_write(&umhelper_sem);
- usermodehelper_disabled = 0;
- up_write(&umhelper_sem);
-}
-
static void helper_lock(void)
{
atomic_inc(&running_helpers);