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    SubjectRe: [PATCH] disable softlockup detection at boottime
    On Wed, 23 Apr 2008 15:16:13 -0500 Dimitri Sivanich wrote:

    > This patch allows softlockup detection to be disabled by specifying
    > a boottime parameter.

    Seems to be missing (a) justification/why and
    (b) entry in Documentation/kernel-parameters.txt


    > Signed-off-by: Dimitri Sivanich <sivanich@sgi.com>
    >
    > Index: linux/kernel/softlockup.c
    > ===================================================================
    > --- linux.orig/kernel/softlockup.c 2008-04-23 13:50:06.000000000 -0500
    > +++ linux/kernel/softlockup.c 2008-04-23 14:39:36.267398531 -0500
    > @@ -24,6 +24,7 @@ static DEFINE_PER_CPU(unsigned long, tou
    > static DEFINE_PER_CPU(unsigned long, print_timestamp);
    > static DEFINE_PER_CPU(struct task_struct *, watchdog_task);
    >
    > +static int __read_mostly softlockup_off;
    > static int __read_mostly did_panic;
    > unsigned long __read_mostly softlockup_thresh = 60;
    >
    > @@ -53,7 +54,8 @@ void touch_softlockup_watchdog(void)
    > {
    > int this_cpu = raw_smp_processor_id();
    >
    > - __raw_get_cpu_var(touch_timestamp) = get_timestamp(this_cpu);
    > + if (!softlockup_off)
    > + __raw_get_cpu_var(touch_timestamp) = get_timestamp(this_cpu);
    > }
    > EXPORT_SYMBOL(touch_softlockup_watchdog);
    >
    > @@ -61,6 +63,9 @@ void touch_all_softlockup_watchdogs(void
    > {
    > int cpu;
    >
    > + if (softlockup_off)
    > + return;
    > +
    > /* Cause each CPU to re-update its timestamp rather than complain */
    > for_each_online_cpu(cpu)
    > per_cpu(touch_timestamp, cpu) = 0;
    > @@ -79,6 +84,9 @@ void softlockup_tick(void)
    > struct pt_regs *regs = get_irq_regs();
    > unsigned long now;
    >
    > + if (softlockup_off)
    > + return;
    > +
    > if (touch_timestamp == 0) {
    > touch_softlockup_watchdog();
    > return;
    > @@ -306,9 +314,19 @@ __init void spawn_softlockup_task(void)
    > void *cpu = (void *)(long)smp_processor_id();
    > int err = cpu_callback(&cpu_nfb, CPU_UP_PREPARE, cpu);
    >
    > + if (softlockup_off)
    > + return;
    > +
    > BUG_ON(err == NOTIFY_BAD);
    > cpu_callback(&cpu_nfb, CPU_ONLINE, cpu);
    > register_cpu_notifier(&cpu_nfb);
    >
    > atomic_notifier_chain_register(&panic_notifier_list, &panic_block);
    > }
    > +
    > +static int __init disable_softlockup_detection(char *str)
    > +{
    > + softlockup_off = 1;
    > + return 1;
    > +}
    > +__setup("nosoftlockup", disable_softlockup_detection);
    > --

    ---
    ~Randy


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