On 08/20/25 at 09:35pm, Baoquan He wrote:
> 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()?
Ok, just found it's in a patch series. Grabbed the patchset and will
have a look.
>
> > /* 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
> >
>
