Commit 6fa99b7f authored Apr 27, 2012 by Will Deacon Committed by Russell King Apr 28, 2012

ARM: 7405/1: kexec: call platform_cpu_kill on the killer rather than the victim



When performing a kexec on an SMP system, the secondary cores are stopped
by calling machine_shutdown(), which in turn issues IPIs to offline the
other CPUs. Unfortunately, this isn't enough to reboot the cores into
a new kernel (since they are just executing a cpu_relax loop somewhere
in memory) so we make use of platform_cpu_kill, part of the CPU hotplug
implementation, to place the cores somewhere safe. This function expects
to be called on the killing CPU for each core that it takes out.

This patch moves the platform_cpu_kill callback out of the IPI handler
and into smp_send_stop, therefore ensuring that it executes on the
killing CPU rather than on the victim, matching what the hotplug code
requires.

Cc: stable@vger.kernel.org
Reported-by: Russell King <rmk+kernel@arm.linux.org.uk>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

parent 6a1c5312

arch/arm/kernel/smp.c

+17 −11

Original line number	Diff line number	Diff line
		@@ -510,10 +510,6 @@ static void ipi_cpu_stop(unsigned int cpu)
		local_fiq_disable();
		local_irq_disable();

		#ifdef CONFIG_HOTPLUG_CPU
		platform_cpu_kill(cpu);
		#endif

		while (1)
		cpu_relax();
		}
		@@ -576,17 +572,25 @@ void smp_send_reschedule(int cpu)
		smp_cross_call(cpumask_of(cpu), IPI_RESCHEDULE);
		}

		#ifdef CONFIG_HOTPLUG_CPU
		static void smp_kill_cpus(cpumask_t *mask)
		{
		unsigned int cpu;
		for_each_cpu(cpu, mask)
		platform_cpu_kill(cpu);
		}
		#else
		static void smp_kill_cpus(cpumask_t *mask) { }
		#endif

		void smp_send_stop(void)
		{
		unsigned long timeout;

		if (num_online_cpus() > 1) {
		struct cpumask mask;

		cpumask_copy(&mask, cpu_online_mask);
		cpumask_clear_cpu(smp_processor_id(), &mask);

		smp_cross_call(&mask, IPI_CPU_STOP);
		}

		/* Wait up to one second for other CPUs to stop */
		timeout = USEC_PER_SEC;
		@@ -595,6 +599,8 @@ void smp_send_stop(void)

		if (num_online_cpus() > 1)
		pr_warning("SMP: failed to stop secondary CPUs\n");

		smp_kill_cpus(&mask);
		}

		/*

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