On 02/09/22 at 02:57pm, Eric DeVolder wrote: > Due to use of CPUHP_AP_ONLINE_DYN, upon CPU unplug, the CPU is > still in the for_each_present_cpu() list when within the > crash_hotplug_handler(). Thus the CPU must be explicitly excluded > when building the new list of CPUs. > > This change identifies in crash_hotplug_handler() the CPU to be > excluded, and the check for excluding the CPU in > crash_prepare_elf64_headers().
This looks good to me, and the particularity of cpu hotplug can be understood well by other code reader. Thanks. Acked-by: Baoquan He <[email protected]> > > Signed-off-by: Eric DeVolder <[email protected]> > --- > kernel/crash_core.c | 10 ++++++++++ > kernel/kexec_file.c | 5 +++++ > 2 files changed, 15 insertions(+) > > diff --git a/kernel/crash_core.c b/kernel/crash_core.c > index 524470e18883..b6942e04a188 100644 > --- a/kernel/crash_core.c > +++ b/kernel/crash_core.c > @@ -550,6 +550,16 @@ static void crash_hotplug_handler(unsigned int hp_action, > /* Flag to differentiate between normal load and hotplug */ > kexec_crash_image->hotplug_event = true; > > + /* > + * Due to use of CPUHP_AP_ONLINE_DYN, upon unplug and during > + * this callback, the CPU is still in the for_each_present_cpu() > + * list. Must explicitly look to exclude this CPU when building > + * new list. > + */ > + kexec_crash_image->offlinecpu = > + (hp_action == KEXEC_CRASH_HP_REMOVE_CPU) ? > + (unsigned int)a : ~0U; > + > /* Now invoke arch-specific update handler */ > arch_crash_hotplug_handler(kexec_crash_image, hp_action, a, b); > > diff --git a/kernel/kexec_file.c b/kernel/kexec_file.c > index 93bb0c0ce66c..339995d42169 100644 > --- a/kernel/kexec_file.c > +++ b/kernel/kexec_file.c > @@ -1314,6 +1314,11 @@ int crash_prepare_elf64_headers(struct kimage *image, > struct crash_mem *mem, > > /* Prepare one phdr of type PT_NOTE for each present CPU */ > for_each_present_cpu(cpu) { > +#ifdef CONFIG_CRASH_HOTPLUG > + /* Skip the soon-to-be offlined cpu */ > + if (image->hotplug_event && (cpu == image->offlinecpu)) > + continue; > +#endif > phdr->p_type = PT_NOTE; > notes_addr = per_cpu_ptr_to_phys(per_cpu_ptr(crash_notes, cpu)); > phdr->p_offset = phdr->p_paddr = notes_addr; > -- > 2.27.0 > _______________________________________________ kexec mailing list [email protected] http://lists.infradead.org/mailman/listinfo/kexec
