linux-kernel - [PATCH 5.4 83/85] alpha: Send stop IPI to send to online CPUs

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]

Date:   Tue, 10 Aug 2021 19:30:56 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Prarit Bhargava <prarit@...hat.com>,
        Richard Henderson <rth@...ddle.net>,
        Ivan Kokshaysky <ink@...assic.park.msu.ru>,
        Matt Turner <mattst88@...il.com>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 5.4 83/85] alpha: Send stop IPI to send to online CPUs

From: Prarit Bhargava <prarit@...hat.com>

[ Upstream commit caace6ca4e06f09413fb8f8a63319594cfb7d47d ]

This issue was noticed while debugging a shutdown issue where some
secondary CPUs are not being shutdown correctly.  A fix for that [1] requires
that secondary cpus be offlined using the cpu_online_mask so that the
stop operation is a no-op if CPU HOTPLUG is disabled.  I, like the author in
[1] looked at the architectures and found that alpha is one of two
architectures that executes smp_send_stop() on all possible CPUs.

On alpha, smp_send_stop() sends an IPI to all possible CPUs but only needs
to send them to online CPUs.

Send the stop IPI to only the online CPUs.

[1] https://lkml.org/lkml/2020/1/10/250

Signed-off-by: Prarit Bhargava <prarit@...hat.com>
Cc: Richard Henderson <rth@...ddle.net>
Cc: Ivan Kokshaysky <ink@...assic.park.msu.ru>
Signed-off-by: Matt Turner <mattst88@...il.com>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 arch/alpha/kernel/smp.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/alpha/kernel/smp.c b/arch/alpha/kernel/smp.c
index 5f90df30be20..06fd42417aa9 100644
--- a/arch/alpha/kernel/smp.c
+++ b/arch/alpha/kernel/smp.c
@@ -585,7 +585,7 @@ void
 smp_send_stop(void)
 {
 	cpumask_t to_whom;
-	cpumask_copy(&to_whom, cpu_possible_mask);
+	cpumask_copy(&to_whom, cpu_online_mask);
 	cpumask_clear_cpu(smp_processor_id(), &to_whom);
 #ifdef DEBUG_IPI_MSG
 	if (hard_smp_processor_id() != boot_cpu_id)
-- 
2.30.2