Add wait_event_killable
Matthew Wilcox [Thu, 6 Dec 2007 17:00:00 +0000 (12:00 -0500)]
Signed-off-by: Matthew Wilcox <willy@linux.intel.com>

include/linux/wait.h

index 0a410a4..1f4fb0a 100644 (file)
@@ -346,6 +346,47 @@ do {                                                                       \
        __ret;                                                          \
 })
 
+#define __wait_event_killable(wq, condition, ret)                      \
+do {                                                                   \
+       DEFINE_WAIT(__wait);                                            \
+                                                                       \
+       for (;;) {                                                      \
+               prepare_to_wait(&wq, &__wait, TASK_KILLABLE);           \
+               if (condition)                                          \
+                       break;                                          \
+               if (!fatal_signal_pending(current)) {                   \
+                       schedule();                                     \
+                       continue;                                       \
+               }                                                       \
+               ret = -ERESTARTSYS;                                     \
+               break;                                                  \
+       }                                                               \
+       finish_wait(&wq, &__wait);                                      \
+} while (0)
+
+/**
+ * wait_event_killable - sleep until a condition gets true
+ * @wq: the waitqueue to wait on
+ * @condition: a C expression for the event to wait for
+ *
+ * The process is put to sleep (TASK_KILLABLE) until the
+ * @condition evaluates to true or a signal is received.
+ * The @condition is checked each time the waitqueue @wq is woken up.
+ *
+ * wake_up() has to be called after changing any variable that could
+ * change the result of the wait condition.
+ *
+ * The function will return -ERESTARTSYS if it was interrupted by a
+ * signal and 0 if @condition evaluated to true.
+ */
+#define wait_event_killable(wq, condition)                             \
+({                                                                     \
+       int __ret = 0;                                                  \
+       if (!(condition))                                               \
+               __wait_event_killable(wq, condition, __ret);            \
+       __ret;                                                          \
+})
+
 /*
  * Must be called with the spinlock in the wait_queue_head_t held.
  */