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x86/smp: Remove pointless wmb()s from native_stop_other_cpus()

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commit 2affa6d6db28855e6340b060b809c23477aa546e upstream.

The wmb()s before sending the IPIs are not synchronizing anything.

If at all then the apic IPI functions have to provide or act as appropriate
barriers.

Remove these cargo cult barriers which have no explanation of what they are
synchronizing.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Borislav Petkov (AMD) <bp@alien8.de>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20230615193330.378358382@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Thomas Gleixner 2023-06-15 22:33:54 +02:00 committed by Greg Kroah-Hartman
parent e47037d28b
commit 50a1abc677
1 changed files with 0 additions and 6 deletions
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6
arch/x86/kernel/smp.c
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@ -184,9 +184,6 @@ static void native_stop_other_cpus(int wait)
cpumask_clear_cpu(cpu, &cpus_stop_mask); cpumask_clear_cpu(cpu, &cpus_stop_mask);
if (!cpumask_empty(&cpus_stop_mask)) { if (!cpumask_empty(&cpus_stop_mask)) {
/* sync above data before sending IRQ */
wmb();
apic_send_IPI_allbutself(REBOOT_VECTOR); apic_send_IPI_allbutself(REBOOT_VECTOR);
/* /*
@ -208,9 +205,6 @@ static void native_stop_other_cpus(int wait)
* CPUs to stop. * CPUs to stop.
*/ */
if (!smp_no_nmi_ipi && !register_stop_handler()) { if (!smp_no_nmi_ipi && !register_stop_handler()) {
/* Sync above data before sending IRQ */
wmb();
pr_emerg("Shutting down cpus with NMI\n"); pr_emerg("Shutting down cpus with NMI\n");
for_each_cpu(cpu, &cpus_stop_mask) for_each_cpu(cpu, &cpus_stop_mask)