Use atomic_try_cmpxchg instead of cmpxchg (*ptr, old, new) == old in crash_kexec(). x86 CMPXCHG instruction returns success in ZF flag, so this change saves a compare after cmpxchg.
No functional change intended. Cc: Eric Biederman <[email protected]> Signed-off-by: Uros Bizjak <[email protected]> --- kernel/kexec_core.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/kernel/kexec_core.c b/kernel/kexec_core.c index be5642a4ec49..bc4c096ab1f3 100644 --- a/kernel/kexec_core.c +++ b/kernel/kexec_core.c @@ -1063,9 +1063,10 @@ __bpf_kfunc void crash_kexec(struct pt_regs *regs) * panic(). Otherwise parallel calls of panic() and crash_kexec() * may stop each other. To exclude them, we use panic_cpu here too. */ + 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) { + + if (atomic_try_cmpxchg(&panic_cpu, &old_cpu, this_cpu)) { /* This is the 1st CPU which comes here, so go ahead. */ __crash_kexec(regs); -- 2.41.0 _______________________________________________ kexec mailing list [email protected] http://lists.infradead.org/mailman/listinfo/kexec
