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.
Signed-off-by: Shaohua Li <shli@xxxxxxxxxxxx>
---
include/linux/wait.h | 36 ++++++++++++++++++++++++++++++++++++
1 file changed, 36 insertions(+)
Index: linux/include/linux/wait.h
===================================================================
--- linux.orig/include/linux/wait.h 2013-08-12 09:13:45.972639924 +0800
+++ linux/include/linux/wait.h 2013-08-12 10:02:20.031998428 +0800
@@ -253,6 +253,42 @@ do { \
__ret; \
})
+#define __wait_event_cmd(wq, condition, cmd1, cmd2) \
+do { \
+ DEFINE_WAIT(__wait); \
+ \
+ for (;;) { \
+ prepare_to_wait(&wq, &__wait, TASK_UNINTERRUPTIBLE); \
+ if (condition) \
+ break; \
+ cmd1; \
+ schedule(); \
+ cmd2; \
+ } \
+ finish_wait(&wq, &__wait); \
+} while (0)
+
+/**
+ * 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, ret) \
do { \
DEFINE_WAIT(__wait); \
--
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