From f213e5502d2e68f141a4e3faadffd03000224192 Mon Sep 17 00:00:00 2001 From: Heiko Carstens Date: Wed, 17 Feb 2021 07:19:09 +0100 Subject: [PATCH] s390/smp: smp_emergency_stop() - move cpumask away from stack Make "cpumask_t cpumask" a static variable to avoid a potential large stack frame. Also protect against potential concurrent callers by introducing a local lock. Note: smp_emergency_stop() gets only called with irqs and machine checks disabled, therefore a cpu local deadlock is not possible. For concurrent callers the first cpu which enters the critical section wins and will stop all other cpus. Signed-off-by: Heiko Carstens Signed-off-by: Vasily Gorbik --- arch/s390/kernel/smp.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/arch/s390/kernel/smp.c b/arch/s390/kernel/smp.c index 3d838b7..7f30d95 100644 --- a/arch/s390/kernel/smp.c +++ b/arch/s390/kernel/smp.c @@ -434,10 +434,12 @@ void notrace smp_yield_cpu(int cpu) */ void notrace smp_emergency_stop(void) { - cpumask_t cpumask; + static arch_spinlock_t lock = __ARCH_SPIN_LOCK_UNLOCKED; + static cpumask_t cpumask; u64 end; int cpu; + arch_spin_lock(&lock); cpumask_copy(&cpumask, cpu_online_mask); cpumask_clear_cpu(smp_processor_id(), &cpumask); @@ -458,6 +460,7 @@ void notrace smp_emergency_stop(void) break; cpu_relax(); } + arch_spin_unlock(&lock); } NOKPROBE_SYMBOL(smp_emergency_stop); -- 2.7.4