Commit 82c08c3e authored Nov 02, 2018 by Yufen Wang Committed by Russell King Nov 08, 2018

ARM: 8808/1: kexec:offline panic_smp_self_stop CPU



In case panic() and panic() called at the same time on different CPUS.
For example:
CPU 0:
  panic()
     __crash_kexec
       machine_crash_shutdown
         crash_smp_send_stop
       machine_kexec
         BUG_ON(num_online_cpus() > 1);

CPU 1:
  panic()
    local_irq_disable
    panic_smp_self_stop

If CPU 1 calls panic_smp_self_stop() before crash_smp_send_stop(), kdump
fails. CPU1 can't receive the ipi irq, CPU1 will be always online.
To fix this problem, this patch split out the panic_smp_self_stop()
and add set_cpu_online(smp_processor_id(), false).

Signed-off-by: Yufen Wang <wangyufen@huawei.com>
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>

parent e2b85f70

arch/arm/kernel/smp.c

+15 −0

Original line number	Diff line number	Diff line
		@@ -693,6 +693,21 @@ void smp_send_stop(void)
		pr_warn("SMP: failed to stop secondary CPUs\n");
		}

		/* In case panic() and panic() called at the same time on CPU1 and CPU2,
		* and CPU 1 calls panic_smp_self_stop() before crash_smp_send_stop()
		* CPU1 can't receive the ipi irqs from CPU2, CPU1 will be always online,
		* kdump fails. So split out the panic_smp_self_stop() and add
		* set_cpu_online(smp_processor_id(), false).
		*/
		void panic_smp_self_stop(void)
		{
		pr_debug("CPU %u will stop doing anything useful since another CPU has paniced\n",
		smp_processor_id());
		set_cpu_online(smp_processor_id(), false);
		while (1)
		cpu_relax();
		}

		/*
		* not supported here
		*/

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