[RFC PATCH 07/14] openrisc/thread_info: Introduce TIF_NOTIFY_IPI flag

[K Prateek Nayak]

Add support for TIF_NOTIFY_IPI on OpenRISC. With TIF_NOTIFY_IPI, a
sender sending an IPI to an idle CPU in TIF_POLLING mode will set the
TIF_NOTIFY_IPI flag in the target's idle tasks's thread_info to pull the
CPU out of idle, as opposed to setting TIF_NEED_RESCHED previously. This
avoids spurious calls to schedule_idle() in cases where an IPI does not
necessarily wake up a task on the idle CPU.

Cc: Jonas Bonn <jonas@xxxxxxxxxxxx>
Cc: Stefan Kristiansson <stefan.kristiansson@xxxxxxxxxxxxx>
Cc: Stafford Horne <shorne@xxxxxxxxx>
Cc: "Rafael J. Wysocki" <rafael@xxxxxxxxxx>
Cc: Daniel Lezcano <daniel.lezcano@xxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Juri Lelli <juri.lelli@xxxxxxxxxx>
Cc: Vincent Guittot <vincent.guittot@xxxxxxxxxx>
Cc: Dietmar Eggemann <dietmar.eggemann@xxxxxxx>
Cc: Steven Rostedt <rostedt@xxxxxxxxxxx>
Cc: Ben Segall <bsegall@xxxxxxxxxx>
Cc: Mel Gorman <mgorman@xxxxxxx>
Cc: Daniel Bristot de Oliveira <bristot@xxxxxxxxxx>
Cc: Valentin Schneider <vschneid@xxxxxxxxxx>
Cc: K Prateek Nayak <kprateek.nayak@xxxxxxx>
Cc: linux-openrisc@xxxxxxxxxxxxxxx
Cc: linux-kernel@xxxxxxxxxxxxxxx
Cc: linux-pm@xxxxxxxxxxxxxxx
Signed-off-by: K Prateek Nayak <kprateek.nayak@xxxxxxx>
---
 arch/openrisc/include/asm/thread_info.h | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/arch/openrisc/include/asm/thread_info.h b/arch/openrisc/include/asm/thread_info.h
index 4af3049c34c2..6a386703bc43 100644
--- a/arch/openrisc/include/asm/thread_info.h
+++ b/arch/openrisc/include/asm/thread_info.h
@@ -92,6 +92,7 @@ register struct thread_info *current_thread_info_reg asm("r10");
 					 * mode
 					 */
 #define TIF_NOTIFY_SIGNAL	5	/* signal notifications exist */
+#define TIF_NOTIFY_IPI		6	/* Pending IPI on TIF_POLLLING idle CPU */
 #define TIF_SYSCALL_TRACEPOINT  8       /* for ftrace syscall instrumentation */
 #define TIF_RESTORE_SIGMASK     9
 #define TIF_POLLING_NRFLAG	16	/* true if poll_idle() is polling						 * TIF_NEED_RESCHED
@@ -104,6 +105,7 @@ register struct thread_info *current_thread_info_reg asm("r10");
 #define _TIF_NEED_RESCHED	(1<<TIF_NEED_RESCHED)
 #define _TIF_SINGLESTEP		(1<<TIF_SINGLESTEP)
 #define _TIF_NOTIFY_SIGNAL	(1<<TIF_NOTIFY_SIGNAL)
+#define _TIF_NOTIFY_IPI		(1<<TIF_NOTIFY_IPI)
 #define _TIF_POLLING_NRFLAG	(1<<TIF_POLLING_NRFLAG)
 
 
-- 
2.34.1