From d8cb0365cbc724b76f680af68351aa15e20d1d3b Mon Sep 17 00:00:00 2001 From: Thomas Gleixner Date: Thu, 15 Jun 2023 22:33:54 +0200 Subject: [PATCH] UPSTREAM: x86/smp: Remove pointless wmb()s from native_stop_other_cpus() 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 Reviewed-by: Borislav Petkov (AMD) Cc: stable@vger.kernel.org Link: https://lore.kernel.org/r/20230615193330.378358382@linutronix.de Signed-off-by: Greg Kroah-Hartman Change-Id: I7541e4c7c65f9bed9b1f28d6c858473986dd50b4 (cherry-picked from commit 50a1abc67702f76968162402d8fb113dd6e22f31) Signed-off-by: Suren Baghdasaryan --- arch/x86/kernel/smp.c | 6 ------ 1 file changed, 6 deletions(-) diff --git a/arch/x86/kernel/smp.c b/arch/x86/kernel/smp.c index 935bc6562fa4..d842875f986f 100644 --- a/arch/x86/kernel/smp.c +++ b/arch/x86/kernel/smp.c @@ -184,9 +184,6 @@ static void native_stop_other_cpus(int wait) cpumask_clear_cpu(cpu, &cpus_stop_mask); if (!cpumask_empty(&cpus_stop_mask)) { - /* sync above data before sending IRQ */ - wmb(); - apic_send_IPI_allbutself(REBOOT_VECTOR); /* @@ -208,9 +205,6 @@ static void native_stop_other_cpus(int wait) * CPUs to stop. */ if (!smp_no_nmi_ipi && !register_stop_handler()) { - /* Sync above data before sending IRQ */ - wmb(); - pr_emerg("Shutting down cpus with NMI\n"); for_each_cpu(cpu, &cpus_stop_mask)