[PATCH v2 10/14] sparc/thread_info: Introduce TIF_NOTIFY_IPI flag

K Prateek Nayak
2024-06-13T18:21:27Z

Add support for TIF_NOTIFY_IPI on SPARC. 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: "David S. Miller" <davem@davemloft.net>
Cc: Andreas Larsson <andreas@gaisler.com>
Cc: "Rafael J. Wysocki" <rafael@kernel.org>
Cc: Daniel Lezcano <daniel.lezcano@linaro.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Juri Lelli <juri.lelli@redhat.com>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Cc: Dietmar Eggemann <dietmar.eggemann@arm.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Ben Segall <bsegall@google.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Daniel Bristot de Oliveira <bristot@redhat.com>
Cc: Valentin Schneider <vschneid@redhat.com>
Cc: K Prateek Nayak <kprateek.nayak@amd.com>
Cc: sparclinux@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Cc: linux-pm@vger.kernel.org
Signed-off-by: K Prateek Nayak <kprateek.nayak@amd.com>
---
v1..v2:
o No changes.
---
arch/sparc/include/asm/thread_info_32.h | 2 ++
arch/sparc/include/asm/thread_info_64.h | 2 ++
2 files changed, 4 insertions(+)

diff --git a/arch/sparc/include/asm/thread_info_32.h b/arch/sparc/include/asm/thread_info_32.h
index 45b4955b253f..f538ede526d1 100644
--- a/arch/sparc/include/asm/thread_info_32.h
+++ b/arch/sparc/include/asm/thread_info_32.h
@@ -105,6 +105,7 @@ register struct thread_info *current_thread_info_reg asm("g6");
#define TIF_NEED_RESCHED 3 /* rescheduling necessary */
#define TIF_RESTORE_SIGMASK 4 /* restore signal mask in do_signal() */
#define TIF_NOTIFY_SIGNAL 5 /* signal notifications exist */
+#define TIF_NOTIFY_IPI 6 /* Pending IPI on TIF_POLLLING idle CPU */
#define TIF_USEDFPU 8 /* FPU was used by this task
* this quantum (SMP) */
#define TIF_POLLING_NRFLAG 9 /* true if poll_idle() is polling
@@ -117,6 +118,7 @@ register struct thread_info *current_thread_info_reg asm("g6");
#define _TIF_SIGPENDING (1<<TIF_SIGPENDING)
#define _TIF_NEED_RESCHED (1<<TIF_NEED_RESCHED)
#define _TIF_NOTIFY_SIGNAL (1<<TIF_NOTIFY_SIGNAL)
+#define _TIF_NOTIFY_IPI (1<<TIF_NOTIFY_IPI)
#define _TIF_USEDFPU (1<<TIF_USEDFPU)
#define _TIF_POLLING_NRFLAG (1<<TIF_POLLING_NRFLAG)

diff --git a/arch/sparc/include/asm/thread_info_64.h b/arch/sparc/include/asm/thread_info_64.h
index 1a44372e2bc0..3558101ccdd1 100644
--- a/arch/sparc/include/asm/thread_info_64.h
+++ b/arch/sparc/include/asm/thread_info_64.h
@@ -194,6 +194,7 @@ extern struct thread_info *current_thread_info(void);
#define TIF_MCDPER 12 /* Precise MCD exception */
#define TIF_MEMDIE 13 /* is terminating due to OOM killer */
#define TIF_POLLING_NRFLAG 14
+#define TIF_NOTIFY_IPI 15 /* Pending IPI on TIF_POLLLING idle CPU */

#define _TIF_SYSCALL_TRACE (1<<TIF_SYSCALL_TRACE)
#define _TIF_NOTIFY_RESUME (1<<TIF_NOTIFY_RESUME)
@@ -208,6 +209,7 @@ extern struct thread_info *current_thread_info(void);
#define _TIF_SYSCALL_AUDIT (1<<TIF_SYSCALL_AUDIT)
#define _TIF_SYSCALL_TRACEPOINT (1<<TIF_SYSCALL_TRACEPOINT)
#define _TIF_POLLING_NRFLAG (1<<TIF_POLLING_NRFLAG)
+#define _TIF_NOTIFY_IPI (1<<TIF_NOTIFY_IPI)

#define _TIF_USER_WORK_MASK ((0xff << TI_FLAG_WSAVED_SHIFT) | \
_TIF_DO_NOTIFY_RESUME_MASK | \
--
2.34.1