On 08/20/25 at 05:14pm, Jinchao Wang wrote:
> crash_kexec() had its own code to exclude
> parallel execution by setting panic_cpu.
> This is already handled by panic_try_start().
>
> Switch to panic_try_start() to remove the
> duplication and keep the logic consistent.
>
> Signed-off-by: Jinchao Wang <wangjinchao...@gmail.com>
> ---
> kernel/crash_core.c | 15 +++------------
> 1 file changed, 3 insertions(+), 12 deletions(-)
>
> diff --git a/kernel/crash_core.c b/kernel/crash_core.c
> index a4ef79591eb2..bb38bbaf3a26 100644
> --- a/kernel/crash_core.c
> +++ b/kernel/crash_core.c
> @@ -4,6 +4,7 @@
> * Copyright (C) 2002-2004 Eric Biederman <ebied...@xmission.com>
> */
>
> +#include "linux/panic.h"
> #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
>
> #include <linux/buildid.h>
> @@ -143,17 +144,7 @@ STACK_FRAME_NON_STANDARD(__crash_kexec);
>
> __bpf_kfunc void crash_kexec(struct pt_regs *regs)
> {
> - int old_cpu, this_cpu;
> -
> - /*
> - * Only one CPU is allowed to execute the crash_kexec() code as with
> - * 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();
> -
> - if (atomic_try_cmpxchg(&panic_cpu, &old_cpu, this_cpu)) {
> + if (panic_try_start()) {
Seriously, where can I find this panic_try_start() and the
panic_reset()?
> /* This is the 1st CPU which comes here, so go ahead. */
> __crash_kexec(regs);
>
> @@ -161,7 +152,7 @@ __bpf_kfunc void crash_kexec(struct pt_regs *regs)
> * Reset panic_cpu to allow another panic()/crash_kexec()
> * call.
> */
> - atomic_set(&panic_cpu, PANIC_CPU_INVALID);
> + panic_reset();
> }
> }
>
> --
> 2.43.0
>
