[tip:,x86/core] x86/smp: Remove pointless wmb()s from native_stop_other_cpus()

Message ID 168726605177.404.10010804348087139293.tip-bot2@tip-bot2
State New
Headers
Series [tip:,x86/core] x86/smp: Remove pointless wmb()s from native_stop_other_cpus() |

Commit Message

tip-bot2 for Thomas Gleixner June 20, 2023, 1 p.m. UTC
  The following commit has been merged into the x86/core branch of tip:

Commit-ID:     2affa6d6db28855e6340b060b809c23477aa546e
Gitweb:        https://git.kernel.org/tip/2affa6d6db28855e6340b060b809c23477aa546e
Author:        Thomas Gleixner <tglx@linutronix.de>
AuthorDate:    Thu, 15 Jun 2023 22:33:54 +02:00
Committer:     Thomas Gleixner <tglx@linutronix.de>
CommitterDate: Tue, 20 Jun 2023 14:51:46 +02:00

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

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

---
 arch/x86/kernel/smp.c | 6 ------
 1 file changed, 6 deletions(-)
  

Patch

diff --git a/arch/x86/kernel/smp.c b/arch/x86/kernel/smp.c
index 935bc65..d842875 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)