linux-kernel - [RFC PATCH v7 18/23] entry/idle: Enter and exit kernel protection during idle entry and exit

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Message-Id: <502aa2680a7ba9c796a370b66c917fd1b0f16b6f.1598643276.git.jdesfossez@digitalocean.com>
Date:   Fri, 28 Aug 2020 15:51:19 -0400
From:   Julien Desfossez <jdesfossez@...italocean.com>
To:     Peter Zijlstra <peterz@...radead.org>,
        Vineeth Pillai <viremana@...ux.microsoft.com>,
        Joel Fernandes <joelaf@...gle.com>,
        Tim Chen <tim.c.chen@...ux.intel.com>,
        Aaron Lu <aaron.lwe@...il.com>,
        Aubrey Li <aubrey.intel@...il.com>,
        Dhaval Giani <dhaval.giani@...cle.com>,
        Chris Hyser <chris.hyser@...cle.com>,
        Nishanth Aravamudan <naravamudan@...italocean.com>
Cc:     "Joel Fernandes (Google)" <joel@...lfernandes.org>,
        mingo@...nel.org, tglx@...utronix.de, pjt@...gle.com,
        torvalds@...ux-foundation.org, linux-kernel@...r.kernel.org,
        fweisbec@...il.com, keescook@...omium.org, kerrnel@...gle.com,
        Phil Auld <pauld@...hat.com>,
        Valentin Schneider <valentin.schneider@....com>,
        Mel Gorman <mgorman@...hsingularity.net>,
        Pawan Gupta <pawan.kumar.gupta@...ux.intel.com>,
        Paolo Bonzini <pbonzini@...hat.com>, vineeth@...byteword.org,
        Chen Yu <yu.c.chen@...el.com>,
        Christian Brauner <christian.brauner@...ntu.com>,
        Agata Gruza <agata.gruza@...el.com>,
        Antonio Gomez Iglesias <antonio.gomez.iglesias@...el.com>,
        graf@...zon.com, konrad.wilk@...cle.com, dfaggioli@...e.com,
        rostedt@...dmis.org, derkling@...gle.com, benbjiang@...cent.com
Subject: [RFC PATCH v7 18/23] entry/idle: Enter and exit kernel protection during idle entry and exit

From: "Joel Fernandes (Google)" <joel@...lfernandes.org>

Make use of the generic_idle_{enter,exit} helper function added in
earlier patches to enter and exit kernel protection.

On exiting idle, protection will be reenabled.

Signed-off-by: Joel Fernandes (Google) <joel@...lfernandes.org>
---
 include/linux/entry-common.h | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/include/linux/entry-common.h b/include/linux/entry-common.h
index 2ea0e09b00d5..c833f2fda542 100644
--- a/include/linux/entry-common.h
+++ b/include/linux/entry-common.h
@@ -374,6 +374,9 @@ void noinstr irqentry_exit(struct pt_regs *regs, irqentry_state_t state);
  */
 static inline void generic_idle_enter(void)
 {
+	/* Entering idle ends the protected kernel region. */
+	sched_core_unsafe_exit();
+
 	rcu_idle_enter();
 }
 
@@ -383,6 +386,9 @@ static inline void generic_idle_enter(void)
 static inline void generic_idle_exit(void)
 {
 	rcu_idle_exit();
+
+	/* Exiting idle (re)starts the protected kernel region. */
+	sched_core_unsafe_enter();
 }
 
 #endif
-- 
2.17.1