wait: add wait_event_cmd()
Add a new API wait_event_cmd(). It's a variant of wait_even() with two
commands executed. One is executed before sleep, another after sleep.
Modified to match use wait.h approach based on suggestion by
Peter Zijlstra <peterz@infradead.org> - neilb
Signed-off-by: Shaohua Li <shli@fusionio.com>
Signed-off-by: NeilBrown <neilb@suse.de>
diff --git a/include/linux/wait.h b/include/linux/wait.h
index 61939ba..eaa00b1 100644
--- a/include/linux/wait.h
+++ b/include/linux/wait.h
@@ -278,6 +278,31 @@
__ret; \
})
+#define __wait_event_cmd(wq, condition, cmd1, cmd2) \
+ (void)___wait_event(wq, condition, TASK_UNINTERRUPTIBLE, 0, 0, \
+ cmd1; schedule(); cmd2)
+
+/**
+ * wait_event_cmd - sleep until a condition gets true
+ * @wq: the waitqueue to wait on
+ * @condition: a C expression for the event to wait for
+ * cmd1: the command will be executed before sleep
+ * cmd2: the command will be executed after sleep
+ *
+ * The process is put to sleep (TASK_UNINTERRUPTIBLE) until the
+ * @condition evaluates to true. 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.
+ */
+#define wait_event_cmd(wq, condition, cmd1, cmd2) \
+do { \
+ if (condition) \
+ break; \
+ __wait_event_cmd(wq, condition, cmd1, cmd2); \
+} while (0)
+
#define __wait_event_interruptible(wq, condition) \
___wait_event(wq, condition, TASK_INTERRUPTIBLE, 0, 0, \
schedule())