On 03/16/23 at 09:44am, Eric DeVolder wrote: > > > On 3/16/23 05:11, Baoquan He wrote: > > On 03/06/23 at 11:22am, Eric DeVolder wrote: > > ...... > > > +static void crash_handle_hotplug_event(unsigned int hp_action, unsigned int cpu) > > > +{ > > > + /* Obtain lock while changing crash information */ > > > + if (kexec_trylock()) { > > > + > > > + /* Check kdump is loaded */ > > > + if (kexec_crash_image) { > > > + struct kimage *image = kexec_crash_image; > > > + > > > + if (hp_action == KEXEC_CRASH_HP_ADD_CPU || > > > + hp_action == KEXEC_CRASH_HP_REMOVE_CPU) > > > + pr_debug("hp_action %u, cpu %u\n", hp_action, cpu); > > > + else > > > + pr_debug("hp_action %u\n", hp_action); > > > + > > > + /* > > > + * When the struct kimage is allocated, the elfcorehdr_index > > > + * is set to -1. Find the segment containing the elfcorehdr, > > > + * if not already found. This works for both the kexec_load > > > + * and kexec_file_load paths. > > > + */ > > > + if (image->elfcorehdr_index < 0) { > > > + unsigned long mem; > > > + unsigned char *ptr; > > > + unsigned int n; > > > + > > > + for (n = 0; n < image->nr_segments; n++) { > > > + mem = image->segment[n].mem; > > > + ptr = kmap_local_page(pfn_to_page(mem >> PAGE_SHIFT)); > > > + if (ptr) { > > > + /* The segment containing elfcorehdr */ > > > + if (memcmp(ptr, ELFMAG, SELFMAG) == 0) { > > > + image->elfcorehdr_index = (int)n; > > > + } > > > + kunmap_local(ptr); > > > + } > > > + } > > > + } > > > + > > > + if (image->elfcorehdr_index < 0) { > > > + pr_err("unable to locate elfcorehdr segment"); > > > + goto out; > > > + } > > > + > > > + /* Needed in order for the segments to be updated */ > > > + arch_kexec_unprotect_crashkres(); > > > + > > > + /* Differentiate between normal load and hotplug update */ > > > + image->hp_action = hp_action; > > > + > > > + /* Now invoke arch-specific update handler */ > > > + arch_crash_handle_hotplug_event(image); > > > + > > > + /* No longer handling a hotplug event */ > > > + image->hp_action = KEXEC_CRASH_HP_NONE; > > > + image->elfcorehdr_updated = true; > > > > It's good to initialize the image->hp_action here, however where do > > you check it? Do you plan to add some check somewhere? > > Hi Baoquan, > The hp_action member is initialized to 0 in do_image_alloc_init(). I've > mapped KEXEC_CRASH_HP_NONE onto 0 on purpose. > > But the use of image->hp_action = KEXEC_CRASH_HP_NONE is to actually > delineate that a hotplug event handling has completed. You can see > imae->hp_action set to hp_action to capture what the triggering event > was, as passed into this function. > > I will go ahead and set image->hp_action = KEXEC_CRASH_HP_NONE; explicitly > in do_kimage_alloc_init(), as that is done for the other crash hotplug members. Yeah, setting image->hp_action = KEXEC_CRASH_HP_NONE in do_kimage_alloc_init() will make code clearer. While I am wondering if we don't initialie image->hp_action to KEXEC_CRASH_HP_NONE, and don't set image->hp_action to KEXEC_CRASH_HP_NONE to actually delineate that a hotplug event handling has completed, what will happen? I mean you set image->hp_action to KEXEC_CRASH_HP_NONE explicitly, where do you check if it should not be KEXEC_CRASH_HP_NONE? In crash_handle_hotplug_event(), we took __kexec_lock and assign the passed hp_action anyway. _______________________________________________ kexec mailing list kexec@xxxxxxxxxxxxxxxxxxx http://lists.infradead.org/mailman/listinfo/kexec