diff options
Diffstat (limited to 'kernel/panic.c')
| -rw-r--r-- | kernel/panic.c | 22 |
1 files changed, 13 insertions, 9 deletions
diff --git a/kernel/panic.c b/kernel/panic.c index ffa037fa77..2807639aab 100644 --- a/kernel/panic.c +++ b/kernel/panic.c @@ -192,14 +192,15 @@ atomic_t panic_cpu = ATOMIC_INIT(PANIC_CPU_INVALID); */ void nmi_panic(struct pt_regs *regs, const char *msg) { - int old_cpu, cpu; + int old_cpu, this_cpu; - cpu = raw_smp_processor_id(); - old_cpu = atomic_cmpxchg(&panic_cpu, PANIC_CPU_INVALID, cpu); + old_cpu = PANIC_CPU_INVALID; + this_cpu = raw_smp_processor_id(); - if (old_cpu == PANIC_CPU_INVALID) + /* atomic_try_cmpxchg updates old_cpu on failure */ + if (atomic_try_cmpxchg(&panic_cpu, &old_cpu, this_cpu)) panic("%s", msg); - else if (old_cpu != cpu) + else if (old_cpu != this_cpu) nmi_panic_self_stop(regs); } EXPORT_SYMBOL(nmi_panic); @@ -311,15 +312,18 @@ void panic(const char *fmt, ...) * stop themself or will wait until they are stopped by the 1st CPU * with smp_send_stop(). * - * `old_cpu == PANIC_CPU_INVALID' means this is the 1st CPU which - * comes here, so go ahead. + * cmpxchg success means this is the 1st CPU which comes here, + * so go ahead. * `old_cpu == this_cpu' means we came from nmi_panic() which sets * panic_cpu to this CPU. In this case, this is also the 1st CPU. */ + old_cpu = PANIC_CPU_INVALID; this_cpu = raw_smp_processor_id(); - old_cpu = atomic_cmpxchg(&panic_cpu, PANIC_CPU_INVALID, this_cpu); - if (old_cpu != PANIC_CPU_INVALID && old_cpu != this_cpu) + /* atomic_try_cmpxchg updates old_cpu on failure */ + if (atomic_try_cmpxchg(&panic_cpu, &old_cpu, this_cpu)) { + /* go ahead */ + } else if (old_cpu != this_cpu) panic_smp_self_stop(); console_verbose(); |