> From: Peter Zijlstra [mailto:peterz at infradead.org] > > On Thu, Aug 06, 2015 at 02:45:43PM +0900, Hidehiro Kawai wrote: > > void crash_kexec(struct pt_regs *regs) > > { > > + int old_cpu, this_cpu; > > + > > + /* > > + * `old_cpu == -1' means we are the first comer and crash_kexec() > > + * was called without entering panic(). > > + * `old_cpu == this_cpu' means crash_kexec() was called from panic(). > > + */ > > + this_cpu = raw_smp_processor_id(); > > + old_cpu = atomic_cmpxchg(&panic_cpu, -1, this_cpu); > > + if (old_cpu != -1 && old_cpu != this_cpu) > > + return; > > This allows recursive calling of crash_kexec(), the Changelog did not > mention that. Is this really required? What part are you arguing? Recursive call of crash_kexec() doesn't happen. In the first place, one of the purpose of this patch is to prevent a recursive call of crash_kexec() in the following case as I stated in the description: CPU 0: oops_end() crash_kexec() mutex_trylock() // acquired <NMI> io_check_error() panic() crash_kexec() mutex_trylock() // failed to acquire infinite loop Also, the logic doesn't change form V1 (although the implementation changed), so I didn't add changelogs any more. Regards, Hidehiro Kawai Hitachi, Ltd. Research & Development Group
