[tip: sched/core] sched/wait: Add wait_event_state()

[tip-bot2 for Peter Zijlstra]

The following commit has been merged into the sched/core branch of tip:

Commit-ID:     3f884a10ab41efe2d495bf8ec8d443d70c500a60
Gitweb:        https://git.kernel.org/tip/3f884a10ab41efe2d495bf8ec8d443d70c500a60
Author:        Peter Zijlstra <peterz@xxxxxxxxxxxxx>
AuthorDate:    Mon, 22 Aug 2022 13:18:21 +02:00
Committer:     Peter Zijlstra <peterz@xxxxxxxxxxxxx>
CommitterDate: Wed, 07 Sep 2022 21:53:49 +02:00

sched/wait: Add wait_event_state()

Allows waiting with a custom @state.

Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Reviewed-by: Ingo Molnar <mingo@xxxxxxxxxx>
Link: https://lore.kernel.org/r/20220822114648.989212021@xxxxxxxxxxxxx
---
 include/linux/wait.h | 28 ++++++++++++++++++++++++++++
 1 file changed, 28 insertions(+)

diff --git a/include/linux/wait.h b/include/linux/wait.h
index 58cfbf8..b926eb9 100644
--- a/include/linux/wait.h
+++ b/include/linux/wait.h
@@ -932,6 +932,34 @@ extern int do_wait_intr_irq(wait_queue_head_t *, wait_queue_entry_t *);
 	__ret;									\
 })
 
+#define __wait_event_state(wq, condition, state)				\
+	___wait_event(wq, condition, state, 0, 0, schedule())
+
+/**
+ * wait_event_state - sleep until a condition gets true
+ * @wq_head: the waitqueue to wait on
+ * @condition: a C expression for the event to wait for
+ * @state: state to sleep in
+ *
+ * The process is put to sleep (@state) until the @condition evaluates to true
+ * or a signal is received (when allowed by @state).  The @condition is checked
+ * each time the waitqueue @wq_head 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
+ * (when allowed by @state) and 0 if @condition evaluated to true.
+ */
+#define wait_event_state(wq_head, condition, state)				\
+({										\
+	int __ret = 0;								\
+	might_sleep();								\
+	if (!(condition))							\
+		__ret = __wait_event_state(wq_head, condition, state);		\
+	__ret;									\
+})
+
 #define __wait_event_killable_timeout(wq_head, condition, timeout)		\
 	___wait_event(wq_head, ___wait_cond_timeout(condition),			\
 		      TASK_KILLABLE, 0, timeout,				\