lkml.org 
[lkml]   [2022]   [Apr]   [25]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    Patch in this message
    /
    Date
    From
    SubjectRe: [PATCH v7 2/8] x86/crash: Introduce new options to support cpu and memory hotplug
    On Tue, Apr 19, 2022 at 04:58:47PM -0500, Eric DeVolder wrote:
    > So in taking this concept and looking at, in particular, patch 4/8
    > "crash: add generic infrastructure for crash hotplug support", I'm not
    > exactly sure how to apply this technique.

    So I took your patch 4 and maimed into what I think it should look like,
    see below.

    Now there's a single ifdef there and the registration routines are
    wrapped in IS_ENABLED() so that you register a callback only when the
    respective stuff - HOTPLUG_CPU or MEMORY_HOTPLUG - is enabled. Otherwise
    the couple of functions are unused but that's not that big of a deal.

    I've also fixed up some other issues I've encountered along the way.

    Holler if there are questions.

    HTH.

    ---
    diff --git a/include/linux/crash_core.h b/include/linux/crash_core.h
    index de62a722431e..b3c32e04d3f0 100644
    --- a/include/linux/crash_core.h
    +++ b/include/linux/crash_core.h
    @@ -84,4 +84,12 @@ int parse_crashkernel_high(char *cmdline, unsigned long long system_ram,
    int parse_crashkernel_low(char *cmdline, unsigned long long system_ram,
    unsigned long long *crash_size, unsigned long long *crash_base);

    +#define KEXEC_CRASH_HP_REMOVE_CPU 0
    +#define KEXEC_CRASH_HP_ADD_CPU 1
    +#define KEXEC_CRASH_HP_REMOVE_MEMORY 2
    +#define KEXEC_CRASH_HP_ADD_MEMORY 3
    +
    +struct kimage;
    +void arch_crash_handle_hotplug_event(struct kimage *image, unsigned int hp_action,
    + unsigned int cpu);
    #endif /* LINUX_CRASH_CORE_H */
    diff --git a/include/linux/kexec.h b/include/linux/kexec.h
    index 02daff1f47dd..d907a1f0d3da 100644
    --- a/include/linux/kexec.h
    +++ b/include/linux/kexec.h
    @@ -307,13 +307,11 @@ struct kimage {
    /* Information for loading purgatory */
    struct purgatory_info purgatory_info;

    -#ifdef CONFIG_CRASH_HOTPLUG
    bool hotplug_event;
    unsigned int offlinecpu;
    bool elfcorehdr_index_valid;
    int elfcorehdr_index;
    #endif
    -#endif

    #ifdef CONFIG_IMA_KEXEC
    /* Virtual address of IMA measurement buffer for kexec syscall */
    @@ -329,15 +327,6 @@ struct kimage {
    unsigned long elf_load_addr;
    };

    -#ifdef CONFIG_CRASH_HOTPLUG
    -void arch_crash_hotplug_handler(struct kimage *image,
    - unsigned int hp_action, unsigned int cpu);
    -#define KEXEC_CRASH_HP_REMOVE_CPU 0
    -#define KEXEC_CRASH_HP_ADD_CPU 1
    -#define KEXEC_CRASH_HP_REMOVE_MEMORY 2
    -#define KEXEC_CRASH_HP_ADD_MEMORY 3
    -#endif /* CONFIG_CRASH_HOTPLUG */
    -
    /* kexec interface functions */
    extern void machine_kexec(struct kimage *image);
    extern int machine_kexec_prepare(struct kimage *image);
    diff --git a/kernel/crash_core.c b/kernel/crash_core.c
    index ecf746243ab2..a6c4ee1d5c86 100644
    --- a/kernel/crash_core.c
    +++ b/kernel/crash_core.c
    @@ -497,57 +497,50 @@ static int __init crash_save_vmcoreinfo_init(void)

    subsys_initcall(crash_save_vmcoreinfo_init);

    -#ifdef CONFIG_CRASH_HOTPLUG
    -void __weak arch_crash_hotplug_handler(struct kimage *image,
    - unsigned int hp_action, unsigned int cpu)
    +void __weak arch_crash_handle_hotplug_event(struct kimage *image, unsigned int hp_action,
    + unsigned int cpu)
    {
    - pr_warn("crash hp: %s not implemented", __func__);
    + WARN(1, "crash hotplug handler not implemented");
    }

    -static void crash_hotplug_handler(unsigned int hp_action,
    - unsigned int cpu)
    +#if defined(CONFIG_HOTPLUG_CPU) || defined(CONFIG_MEMORY_HOTPLUG)
    +static void handle_hotplug_event(unsigned int hp_action, unsigned int cpu)
    {
    - /* Obtain lock while changing crash information */
    - if (!mutex_trylock(&kexec_mutex))
    + if (!kexec_crash_image)
    return;

    - /* Check kdump is loaded */
    - if (kexec_crash_image) {
    - pr_debug("crash hp: hp_action %u, cpu %u", hp_action, cpu);
    + mutex_lock(&kexec_mutex);

    - /* Needed in order for the segments to be updated */
    - arch_kexec_unprotect_crashkres();
    + pr_debug("crash hotplug: hp_action %u, cpu %u", hp_action, cpu);

    - /* Flag to differentiate between normal load and hotplug */
    - kexec_crash_image->hotplug_event = true;
    + /* Needed in order for the segments to be updated */
    + arch_kexec_unprotect_crashkres();

    - /* Now invoke arch-specific update handler */
    - arch_crash_hotplug_handler(kexec_crash_image, hp_action, cpu);
    + /* Flag to differentiate between normal load and hotplug */
    + kexec_crash_image->hotplug_event = true;

    - /* No longer handling a hotplug event */
    - kexec_crash_image->hotplug_event = false;
    + /* Now invoke arch-specific update handler */
    + arch_crash_handle_hotplug_event(kexec_crash_image, hp_action, cpu);

    - /* Change back to read-only */
    - arch_kexec_protect_crashkres();
    - }
    + /* No longer handling a hotplug event */
    + kexec_crash_image->hotplug_event = false;
    +
    + /* Change back to read-only */
    + arch_kexec_protect_crashkres();

    /* Release lock now that update complete */
    mutex_unlock(&kexec_mutex);
    }

    -#if defined(CONFIG_MEMORY_HOTPLUG)
    -static int crash_memhp_notifier(struct notifier_block *nb,
    - unsigned long val, void *v)
    +static int crash_memhp_notifier(struct notifier_block *nb, unsigned long val, void *v)
    {
    - struct memory_notify *mhp = v;
    -
    switch (val) {
    case MEM_ONLINE:
    - crash_hotplug_handler(KEXEC_CRASH_HP_ADD_MEMORY, -1U);
    + handle_hotplug_event(KEXEC_CRASH_HP_ADD_MEMORY, -1U);
    break;

    case MEM_OFFLINE:
    - crash_hotplug_handler(KEXEC_CRASH_HP_REMOVE_MEMORY, -1U);
    + handle_hotplug_event(KEXEC_CRASH_HP_REMOVE_MEMORY, -1U);
    break;
    }
    return NOTIFY_OK;
    @@ -557,38 +550,33 @@ static struct notifier_block crash_memhp_nb = {
    .notifier_call = crash_memhp_notifier,
    .priority = 0
    };
    -#endif

    -#if defined(CONFIG_HOTPLUG_CPU)
    static int crash_cpuhp_online(unsigned int cpu)
    {
    - crash_hotplug_handler(KEXEC_CRASH_HP_ADD_CPU, cpu);
    + handle_hotplug_event(KEXEC_CRASH_HP_ADD_CPU, cpu);
    return 0;
    }

    static int crash_cpuhp_offline(unsigned int cpu)
    {
    - crash_hotplug_handler(KEXEC_CRASH_HP_REMOVE_CPU, cpu);
    + handle_hotplug_event(KEXEC_CRASH_HP_REMOVE_CPU, cpu);
    return 0;
    }
    -#endif

    static int __init crash_hotplug_init(void)
    {
    int result = 0;

    -#if defined(CONFIG_MEMORY_HOTPLUG)
    - register_memory_notifier(&crash_memhp_nb);
    -#endif
    + if (IS_ENABLED(CONFIG_MEMORY_HOTPLUG))
    + register_memory_notifier(&crash_memhp_nb);

    -#if defined(CONFIG_HOTPLUG_CPU)
    - result = cpuhp_setup_state_nocalls(CPUHP_AP_ONLINE_DYN,
    - "crash/cpuhp",
    - crash_cpuhp_online, crash_cpuhp_offline);
    -#endif
    + if (IS_ENABLED(CONFIG_HOTPLUG_CPU))
    + result = cpuhp_setup_state_nocalls(CPUHP_AP_ONLINE_DYN,
    + "crash/cpuhp",
    + crash_cpuhp_online,
    + crash_cpuhp_offline);

    return result;
    }
    -
    subsys_initcall(crash_hotplug_init);
    -#endif /* CONFIG_CRASH_HOTPLUG */
    +#endif
    --
    Regards/Gruss,
    Boris.

    https://people.kernel.org/tglx/notes-about-netiquette

    \
     
     \ /
      Last update: 2022-04-25 21:27    [W:4.159 / U:0.376 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site