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Commit 742e85fa authored by Prarit Bhargava's avatar Prarit Bhargava Committed by Greg Kroah-Hartman
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alpha: Send stop IPI to send to online CPUs 

[ 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: default avatarPrarit Bhargava <prarit@redhat.com>
Cc: Richard Henderson <rth@twiddle.net>
Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
Signed-off-by: default avatarMatt Turner <mattst88@gmail.com>
Signed-off-by: default avatarSasha Levin <sashal@kernel.org>
parent 26946d21

arch/alpha/kernel/smp.c

+1 −1
Original line number Diff line number Diff line
@@ -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)