Commit f213e550 authored by Heiko Carstens's avatar Heiko Carstens Committed by Vasily Gorbik
Browse files

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: default avatarHeiko Carstens <hca@linux.ibm.com>
Signed-off-by: default avatarVasily Gorbik <gor@linux.ibm.com>
parent 62c8dca9

arch/s390/kernel/smp.c

+4 −1
Original line number Diff line number Diff line
@@ -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);