linux-kernel - [PATCH v2 14/35] rcu: limit PREEMPT_RCU to full preemption under PREEMPT

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <20240528003521.979836-15-ankur.a.arora@oracle.com>
Date: Mon, 27 May 2024 17:35:00 -0700
From: Ankur Arora <ankur.a.arora@...cle.com>
To: linux-kernel@...r.kernel.org
Cc: tglx@...utronix.de, peterz@...radead.org, torvalds@...ux-foundation.org,
        paulmck@...nel.org, rostedt@...dmis.org, mark.rutland@....com,
        juri.lelli@...hat.com, joel@...lfernandes.org, raghavendra.kt@....com,
        sshegde@...ux.ibm.com, boris.ostrovsky@...cle.com,
        konrad.wilk@...cle.com, Ankur Arora <ankur.a.arora@...cle.com>
Subject: [PATCH v2 14/35] rcu: limit PREEMPT_RCU to full preemption under PREEMPT_AUTO

Under PREEMPT_AUTO, CONFIG_PREEMPTION is enabled, and much like
PREEMPT_DYNAMIC, PREEMPT_AUTO also allows for dynamic switching
of preemption models.

The RCU model, however, is fixed at compile time.

Now, RCU typically selects PREEMPT_RCU if CONFIG_PREEMPTION is enabled.
Given the trade-offs between PREEMPT_RCU=y and PREEMPT_RCU=n, some
configurations might prefer the stronger forward-progress guarantees
of PREEMPT_RCU=n.

Accordingly, select PREEMPT_RCU=y only if the user selects
CONFIG_PREEMPT at compile time.

Suggested-by: Paul E. McKenney <paulmck@...nel.org>
Signed-off-by: Ankur Arora <ankur.a.arora@...cle.com>
---
 kernel/rcu/Kconfig | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/rcu/Kconfig b/kernel/rcu/Kconfig
index e7d2dd267593..9dedb70ac2e6 100644
--- a/kernel/rcu/Kconfig
+++ b/kernel/rcu/Kconfig
@@ -18,7 +18,7 @@ config TREE_RCU
 
 config PREEMPT_RCU
 	bool
-	default y if PREEMPTION
+	default y if (PREEMPT || PREEMPT_DYNAMIC || PREEMPT_RT)
 	select TREE_RCU
 	help
 	  This option selects the RCU implementation that is
-- 
2.31.1