linux-kernel - [PATCH v5 09/19] locking/mutex: Switch to mutex handoffs for CONFIG_PROXY

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Message-ID: <20230819060915.3001568-10-jstultz@google.com>
Date:   Sat, 19 Aug 2023 06:08:43 +0000
From:   John Stultz <jstultz@...gle.com>
To:     LKML <linux-kernel@...r.kernel.org>
Cc:     Peter Zijlstra <peterz@...radead.org>,
        Joel Fernandes <joelaf@...gle.com>,
        Qais Yousef <qyousef@...gle.com>,
        Ingo Molnar <mingo@...hat.com>,
        Juri Lelli <juri.lelli@...hat.com>,
        Vincent Guittot <vincent.guittot@...aro.org>,
        Dietmar Eggemann <dietmar.eggemann@....com>,
        Valentin Schneider <vschneid@...hat.com>,
        Steven Rostedt <rostedt@...dmis.org>,
        Ben Segall <bsegall@...gle.com>,
        Zimuzo Ezeozue <zezeozue@...gle.com>,
        Youssef Esmat <youssefesmat@...gle.com>,
        Mel Gorman <mgorman@...e.de>,
        Daniel Bristot de Oliveira <bristot@...hat.com>,
        Will Deacon <will@...nel.org>,
        Waiman Long <longman@...hat.com>,
        Boqun Feng <boqun.feng@...il.com>,
        "Paul E . McKenney" <paulmck@...nel.org>, kernel-team@...roid.com,
        Valentin Schneider <valentin.schneider@....com>,
        "Connor O'Brien" <connoro@...gle.com>,
        John Stultz <jstultz@...gle.com>
Subject: [PATCH v5 09/19] locking/mutex: Switch to mutex handoffs for CONFIG_PROXY_EXEC

From: Peter Zijlstra <peterz@...radead.org>

Just the very earliest framework logic to provide
the config option and switch to using mutex
handoffs.

Cc: Joel Fernandes <joelaf@...gle.com>
Cc: Qais Yousef <qyousef@...gle.com>
Cc: Ingo Molnar <mingo@...hat.com>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Juri Lelli <juri.lelli@...hat.com>
Cc: Vincent Guittot <vincent.guittot@...aro.org>
Cc: Dietmar Eggemann <dietmar.eggemann@....com>
Cc: Valentin Schneider <vschneid@...hat.com>
Cc: Steven Rostedt <rostedt@...dmis.org>
Cc: Ben Segall <bsegall@...gle.com>
Cc: Zimuzo Ezeozue <zezeozue@...gle.com>
Cc: Youssef Esmat <youssefesmat@...gle.com>
Cc: Mel Gorman <mgorman@...e.de>
Cc: Daniel Bristot de Oliveira <bristot@...hat.com>
Cc: Will Deacon <will@...nel.org>
Cc: Waiman Long <longman@...hat.com>
Cc: Boqun Feng <boqun.feng@...il.com>
Cc: "Paul E . McKenney" <paulmck@...nel.org>
Cc: kernel-team@...roid.com
Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
[rebased, added comments and changelog]
Signed-off-by: Juri Lelli <juri.lelli@...hat.com>
[Fixed rebase conflicts]
[squashed sched: Ensure blocked_on is always guarded by blocked_lock]
Signed-off-by: Valentin Schneider <valentin.schneider@....com>
[fix rebase conflicts, various fixes & tweaks commented inline]
[squashed sched: Use rq->curr vs rq->proxy checks]
Signed-off-by: Connor O'Brien <connoro@...gle.com>
[jstultz: Split out only the very basic initial framework
 for proxy logic from a larger patch.]
Signed-off-by: John Stultz <jstultz@...gle.com>
---
v5:
Split out from core proxy patch
---
 kernel/Kconfig.locks   | 2 +-
 kernel/locking/mutex.c | 5 +++++
 2 files changed, 6 insertions(+), 1 deletion(-)

diff --git a/kernel/Kconfig.locks b/kernel/Kconfig.locks
index 4198f0273ecd..791c98f1d329 100644
--- a/kernel/Kconfig.locks
+++ b/kernel/Kconfig.locks
@@ -226,7 +226,7 @@ config ARCH_SUPPORTS_ATOMIC_RMW
 
 config MUTEX_SPIN_ON_OWNER
 	def_bool y
-	depends on SMP && ARCH_SUPPORTS_ATOMIC_RMW
+	depends on SMP && ARCH_SUPPORTS_ATOMIC_RMW && !PROXY_EXEC
 
 config RWSEM_SPIN_ON_OWNER
        def_bool y
diff --git a/kernel/locking/mutex.c b/kernel/locking/mutex.c
index 687009eca2d1..5125bbab4119 100644
--- a/kernel/locking/mutex.c
+++ b/kernel/locking/mutex.c
@@ -913,6 +913,10 @@ static noinline void __sched __mutex_unlock_slowpath(struct mutex *lock, unsigne
 
 	mutex_release(&lock->dep_map, ip);
 
+#ifdef CONFIG_PROXY_EXEC
+	/* Always force HANDOFF for Proxy Exec for now. Revisit. */
+	owner = MUTEX_FLAG_HANDOFF;
+#else /* CONFIG_PROXY_EXEC */
 	/*
 	 * Release the lock before (potentially) taking the spinlock such that
 	 * other contenders can get on with things ASAP.
@@ -935,6 +939,7 @@ static noinline void __sched __mutex_unlock_slowpath(struct mutex *lock, unsigne
 			return;
 		}
 	}
+#endif /* CONFIG_PROXY_EXEC */
 
 	raw_spin_lock_irqsave(&lock->wait_lock, flags);
 	debug_mutex_unlock(lock);
-- 
2.42.0.rc1.204.g551eb34607-goog