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| author | Uros Bizjak <ubizjak@gmail.com> | 2023-11-14 17:12:01 +0100 |
|---|---|---|
| committer | Andrew Morton <akpm@linux-foundation.org> | 2023-12-10 17:21:33 -0800 |
| commit | 0311d8272406b2ec47f485bef887723cc352a489 (patch) | |
| tree | 0938025c927835f78755743039c308cf598bd3fc /kernel/kexec_core.c | |
| parent | 1ee918ffa6d4776a69708b013fd7e7006619158a (diff) | |
| download | lwn-0311d8272406b2ec47f485bef887723cc352a489.tar.gz lwn-0311d8272406b2ec47f485bef887723cc352a489.zip | |
kexec: use atomic_try_cmpxchg in crash_kexec
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.
Link: https://lkml.kernel.org/r/20231114161228.108516-1-ubizjak@gmail.com
Signed-off-by: Uros Bizjak <ubizjak@gmail.com>
Acked-by: Baoquan He <bhe@redhat.com>
Cc: Eric Biederman <ebiederm@xmission.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Diffstat (limited to 'kernel/kexec_core.c')
| -rw-r--r-- | kernel/kexec_core.c | 5 |
1 files 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); |