linux-kernel - [PATCH v3 5/6] sched/wait: Add wait_event

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Date:   Mon, 22 Aug 2022 13:18:21 +0200
From:   Peter Zijlstra <peterz@...radead.org>
To:     rjw@...ysocki.net, oleg@...hat.com, mingo@...nel.org,
        vincent.guittot@...aro.org, dietmar.eggemann@....com,
        rostedt@...dmis.org, mgorman@...e.de, ebiederm@...ssion.com,
        bigeasy@...utronix.de, Will Deacon <will@...nel.org>
Cc:     linux-kernel@...r.kernel.org, peterz@...radead.org, tj@...nel.org,
        linux-pm@...r.kernel.org
Subject: [PATCH v3 5/6] sched/wait: Add wait_event_state()

Allows waiting with a custom @state.

Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
---
 include/linux/wait.h |   28 ++++++++++++++++++++++++++++
 1 file changed, 28 insertions(+)

--- a/include/linux/wait.h
+++ b/include/linux/wait.h
@@ -931,6 +931,34 @@ extern int do_wait_intr_irq(wait_queue_h
 	__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.  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 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,				\