linux-kernel - [PATCH 02/21] rcu: Tag rcu_irq_*

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Date:   Thu, 19 May 2022 16:58:04 +0200
From:   Frederic Weisbecker <frederic@...nel.org>
To:     LKML <linux-kernel@...r.kernel.org>
Cc:     Frederic Weisbecker <frederic@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Phil Auld <pauld@...hat.com>,
        Alex Belits <abelits@...vell.com>,
        Nicolas Saenz Julienne <nsaenz@...nel.org>,
        Xiongfeng Wang <wangxiongfeng2@...wei.com>,
        Neeraj Upadhyay <quic_neeraju@...cinc.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Yu Liao <liaoyu15@...wei.com>,
        Boqun Feng <boqun.feng@...il.com>,
        "Paul E . McKenney" <paulmck@...nel.org>,
        Marcelo Tosatti <mtosatti@...hat.com>,
        Paul Gortmaker <paul.gortmaker@...driver.com>,
        Uladzislau Rezki <uladzislau.rezki@...y.com>,
        Joel Fernandes <joel@...lfernandes.org>,
        Mark Rutland <mark.rutland@....com>
Subject: [PATCH 02/21] rcu: Tag rcu_irq_*_irqson() as noinstr

rcu_irq_*_irqson() functions can't be safely instrumented. Since they
enter/exit to/from RCU idle mode, those functions must be tagged as
"noinstr".

Unfortunately this involves converting the instrumentable
local_irq_save()/local_irq_restore() to their raw counterparts. Precious
debugging informations might be lost on the way until a better way out
is found.

Signed-off-by: Frederic Weisbecker <frederic@...nel.org>
Cc: Paul E. McKenney <paulmck@...nel.org>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: Neeraj Upadhyay <quic_neeraju@...cinc.com>
Cc: Uladzislau Rezki <uladzislau.rezki@...y.com>
Cc: Joel Fernandes <joel@...lfernandes.org>
Cc: Boqun Feng <boqun.feng@...il.com>
Cc: Nicolas Saenz Julienne <nsaenz@...nel.org>
Cc: Marcelo Tosatti <mtosatti@...hat.com>
Cc: Xiongfeng Wang <wangxiongfeng2@...wei.com>
Cc: Yu Liao<liaoyu15@...wei.com>
Cc: Phil Auld <pauld@...hat.com>
Cc: Paul Gortmaker<paul.gortmaker@...driver.com>
Cc: Alex Belits <abelits@...vell.com>
---
 kernel/rcu/tree.c | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index 02233b17cce0..ff97264d8077 100644
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -843,13 +843,13 @@ void rcu_irq_exit_check_preempt(void)
  * If you add or remove a call to rcu_irq_exit_irqson(), be sure to test
  * with CONFIG_RCU_EQS_DEBUG=y.
  */
-void rcu_irq_exit_irqson(void)
+void noinstr rcu_irq_exit_irqson(void)
 {
 	unsigned long flags;
 
-	local_irq_save(flags);
+	raw_local_irq_save(flags);
 	rcu_irq_exit();
-	local_irq_restore(flags);
+	raw_local_irq_restore(flags);
 }
 
 /*
@@ -1081,13 +1081,13 @@ noinstr void rcu_irq_enter(void)
  * If you add or remove a call to rcu_irq_enter_irqson(), be sure to test
  * with CONFIG_RCU_EQS_DEBUG=y.
  */
-void rcu_irq_enter_irqson(void)
+void noinstr rcu_irq_enter_irqson(void)
 {
 	unsigned long flags;
 
-	local_irq_save(flags);
+	raw_local_irq_save(flags);
 	rcu_irq_enter();
-	local_irq_restore(flags);
+	raw_local_irq_restore(flags);
 }
 
 /*
-- 
2.25.1