On Fri, Nov 19, 2010 at 11:08:30AM +0100, Per Fransson wrote:
> When kexec is used to start a crash kernel the other cores
> are notified. These non-crashing cores will save their state
> in the crash notes and then do nothing.
>
> Signed-off-by: Per Fransson <per.xx.fransson at stericsson.com>
> ---
> arch/arm/kernel/machine_kexec.c | 28 ++++++++++++++++++++++++++++
> 1 files changed, 28 insertions(+), 0 deletions(-)
>
> diff --git a/arch/arm/kernel/machine_kexec.c b/arch/arm/kernel/machine_kexec.c
> index 3a8fd51..56683db 100644
> --- a/arch/arm/kernel/machine_kexec.c
> +++ b/arch/arm/kernel/machine_kexec.c
> @@ -23,6 +23,8 @@ extern unsigned long kexec_indirection_page;
> extern unsigned long kexec_mach_type;
> extern unsigned long kexec_boot_atags;
>
> +static atomic_t waiting_for_crash_ipi;
> +
> /*
> * Provide a dummy crash_notes definition while crash dump arrives to arm.
> * This prevents breakage of crash_notes attribute in kernel/ksysfs.c.
> @@ -37,8 +39,34 @@ void machine_kexec_cleanup(struct kimage *image)
> {
> }
>
> +void machine_crash_nonpanic_core(void *unused)
> +{
> + struct pt_regs regs;
> +
> + crash_setup_regs(®s, NULL);
> + printk(KERN_EMERG "CPU %u will stop doing anything useful since another CPU has crashed\n",
> + smp_processor_id());
> + crash_save_cpu(®s, smp_processor_id());
> + flush_cache_all();
> +
> + atomic_dec(&waiting_for_crash_ipi);
> + while (1)
> + cpu_relax();
> +}
> +
> void machine_crash_shutdown(struct pt_regs *regs)
> {
> + unsigned long msecs;
> +
> + atomic_set(&waiting_for_crash_ipi, num_online_cpus() - 1);
> +
> + local_irq_enable();
I wonder whether it is good idea to enable interrupts here? What
if we came here from an interrupt handler with interrupts already
disabled?
I guess you did this because smp_call_function() needs to have
interrupts enabled, right?
As we still need to make sure that all the secondary CPUs are
stopped, should we do just something like:
smp_send_stop();
and then in ipi_cpu_stop() we check whether oops_in_progress is set
and save the cpu state before entering that never-ending loop?
Regards,
MW
> + smp_call_function(machine_crash_nonpanic_core, NULL, false);
> + msecs = 1000; /* Wait at most a second for the other cpus to stop */
> + while ((atomic_read(&waiting_for_crash_ipi) > 0) && msecs) {
> + mdelay(1);
> + msecs--;
> + }
> local_irq_disable();
> crash_save_cpu(regs, smp_processor_id());
>
> --
> 1.7.2.2
>
>
> _______________________________________________
> linux-arm-kernel mailing list
> linux-arm-kernel at lists.infradead.org
> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
