CHROMIUM: usb: ehci: Only sleep for post-resume handover if devices use persist

[cascardo/linux.git] / kernel / kmod.c

diff --git a/kernel/kmod.c b/kernel/kmod.c
index 957a7aa..da7fcca 100644 (file)
--- a/kernel/kmod.c
+++ b/kernel/kmod.c
@@ -333,23 +333,74 @@ 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
  */
 #define RUNNING_HELPERS_TIMEOUT        (5 * HZ)
 
-void read_lock_usermodehelper(void)
+int usermodehelper_read_trylock(void)
 {
+       int ret = 0;
+
        down_read(&umhelper_sem);
+       if (usermodehelper_disabled) {
+               up_read(&umhelper_sem);
+               ret = -EAGAIN;
+       }
+       return ret;
 }
-EXPORT_SYMBOL_GPL(read_lock_usermodehelper);
+EXPORT_SYMBOL_GPL(usermodehelper_read_trylock);
 
-void read_unlock_usermodehelper(void)
+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);
 }
-EXPORT_SYMBOL_GPL(read_unlock_usermodehelper);
+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
@@ -374,31 +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);
-}
-
-/**
- * usermodehelper_is_disabled - check if new helpers are allowed to be started
- */
-bool usermodehelper_is_disabled(void)
-{
-       return usermodehelper_disabled;
-}
-EXPORT_SYMBOL_GPL(usermodehelper_is_disabled);
-
 static void helper_lock(void)
 {
        atomic_inc(&running_helpers);