[patch V2 06/15] rcuwait: Add @state argument to rcuwait_wait_event()

Thomas Gleixner
2020-03-18T20:48:17Z

Extend rcuwait_wait_event() with a state variable so that it is not
restricted to UNINTERRUPTIBLE waits.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Davidlohr Bueso <dave@stgolabs.net>
---
include/linux/rcuwait.h | 12 ++++++++++--
kernel/locking/percpu-rwsem.c | 2 +-
2 files changed, 11 insertions(+), 3 deletions(-)

--- a/include/linux/rcuwait.h
+++ b/include/linux/rcuwait.h
@@ -3,6 +3,7 @@
#define _LINUX_RCUWAIT_H_

#include <linux/rcupdate.h>
+#include <linux/sched/signal.h>

/*
* rcuwait provides a way of blocking and waking up a single
@@ -30,23 +31,30 @@ extern void rcuwait_wake_up(struct rcuwa
* The caller is responsible for locking around rcuwait_wait_event(),
* such that writes to @task are properly serialized.
*/
-#define rcuwait_wait_event(w, condition) \
+#define rcuwait_wait_event(w, condition, state) \
({ \
+ int __ret = 0; \
rcu_assign_pointer((w)->task, current); \
for (;;) { \
/* \
* Implicit barrier (A) pairs with (B) in \
* rcuwait_wake_up(). \
*/ \
- set_current_state(TASK_UNINTERRUPTIBLE); \
+ set_current_state(state); \
if (condition) \
break; \
\
+ if (signal_pending_state(state, current)) { \
+ __ret = -EINTR; \
+ break; \
+ } \
+ \
schedule(); \
} \
\
WRITE_ONCE((w)->task, NULL); \
__set_current_state(TASK_RUNNING); \
+ __ret; \
})

#endif /* _LINUX_RCUWAIT_H_ */
--- a/kernel/locking/percpu-rwsem.c
+++ b/kernel/locking/percpu-rwsem.c
@@ -162,7 +162,7 @@ void percpu_down_write(struct percpu_rw_
*/

/* Wait for all now active readers to complete. */
- rcuwait_wait_event(&sem->writer, readers_active_check(sem));
+ rcuwait_wait_event(&sem->writer, readers_active_check(sem), TASK_UNINTERRUPTIBLE);
}
EXPORT_SYMBOL_GPL(percpu_down_write);