From: Uros Bizjak Date: Thu, 23 Nov 2023 20:34:22 +0000 (+0100) Subject: x86/smp: Move the call to smp_processor_id() after the early exit in native_stop_othe... X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=9d1c8f21533729b6ead531b676fa7d327cf00819;p=linux.git x86/smp: Move the call to smp_processor_id() after the early exit in native_stop_other_cpus() Improve code generation in native_stop_other_cpus() a tiny bit: smp_processor_id() accesses a per-CPU variable, so the compiler is not able to move the call after the early exit on its own. Also rename the "cpu" variable to a more descriptive "this_cpu", and use 'cpu' as a separate iterator variable later in the function. No functional change intended. Signed-off-by: Uros Bizjak Signed-off-by: Ingo Molnar Link: https://lore.kernel.org/r/20231123203605.3474745-1-ubizjak@gmail.com --- diff --git a/arch/x86/kernel/smp.c b/arch/x86/kernel/smp.c index 6eb06d001bcc6..65dd44e3fc1cf 100644 --- a/arch/x86/kernel/smp.c +++ b/arch/x86/kernel/smp.c @@ -148,14 +148,15 @@ static int register_stop_handler(void) static void native_stop_other_cpus(int wait) { - unsigned int cpu = smp_processor_id(); + unsigned int this_cpu; unsigned long flags, timeout; if (reboot_force) return; /* Only proceed if this is the first CPU to reach this code */ - if (atomic_cmpxchg(&stopping_cpu, -1, cpu) != -1) + this_cpu = smp_processor_id(); + if (atomic_cmpxchg(&stopping_cpu, -1, this_cpu) != -1) return; /* For kexec, ensure that offline CPUs are out of MWAIT and in HLT */ @@ -190,7 +191,7 @@ static void native_stop_other_cpus(int wait) * NMIs. */ cpumask_copy(&cpus_stop_mask, cpu_online_mask); - cpumask_clear_cpu(cpu, &cpus_stop_mask); + cpumask_clear_cpu(this_cpu, &cpus_stop_mask); if (!cpumask_empty(&cpus_stop_mask)) { apic_send_IPI_allbutself(REBOOT_VECTOR); @@ -234,6 +235,8 @@ static void native_stop_other_cpus(int wait) * CPUs to stop. */ if (!smp_no_nmi_ipi && !register_stop_handler()) { + unsigned int cpu; + pr_emerg("Shutting down cpus with NMI\n"); for_each_cpu(cpu, &cpus_stop_mask)