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Commit 2440c01e authored by Anton Blanchard's avatar Anton Blanchard Committed by Benjamin Herrenschmidt
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powerpc/kdump: Only save CPU state first time through the secondary CPU capture code 



We might enter the secondary CPU capture code twice, eg if we have to
unstick some CPUs with a system reset. In this case we don't want to
overwrite the state on CPUs that had made it into the capture code OK,
so use the cpus_state_saved cpumask for that and make it local to
crash_ipi_callback.

For controlling progress now use atomic_t cpus_in_crash to count how
many CPUs have made it into the kdump code, and time_to_dump to tell
everyone it's time to dump.

Signed-off-by: default avatarAnton Blanchard <anton@samba.org>
Signed-off-by: default avatarBenjamin Herrenschmidt <benh@kernel.crashing.org>
parent 549e88a1

arch/powerpc/kernel/crash.c

+21 −12
Original line number Diff line number Diff line
@@ -46,7 +46,8 @@ 


/* This keeps a track of which one is the crashing cpu. */

int crashing_cpu = -1;

static cpumask_t cpus_in_crash = CPU_MASK_NONE;

static atomic_t cpus_in_crash;

static int time_to_dump;



#define CRASH_HANDLER_MAX 3

/* NULL terminated list of shutdown handles */
@@ -67,21 +68,27 @@ static int handle_fault(struct pt_regs *regs) 


void crash_ipi_callback(struct pt_regs *regs)

{

	static cpumask_t cpus_state_saved = CPU_MASK_NONE;



	int cpu = smp_processor_id();



	if (!cpu_online(cpu))

		return;



	hard_irq_disable();

	if (!cpumask_test_cpu(cpu, &cpus_in_crash))

	if (!cpumask_test_cpu(cpu, &cpus_state_saved)) {

		crash_save_cpu(regs, cpu);

	cpumask_set_cpu(cpu, &cpus_in_crash);

		cpumask_set_cpu(cpu, &cpus_state_saved);

	}



	atomic_inc(&cpus_in_crash);

	smp_mb__after_atomic_inc();



	/*

	 * Starting the kdump boot.

	 * This barrier is needed to make sure that all CPUs are stopped.

	 */

	while (!cpumask_test_cpu(crashing_cpu, &cpus_in_crash))

	while (!time_to_dump)

		cpu_relax();



	if (ppc_md.kexec_cpu_down)
@@ -115,19 +122,18 @@ static void crash_kexec_prepare_cpus(int cpu) 
	 * respond.

	 */

	msecs = IPI_TIMEOUT;

	while ((cpumask_weight(&cpus_in_crash) < ncpus) && (--msecs > 0)) {

	while ((atomic_read(&cpus_in_crash) < ncpus) && (--msecs > 0))

		mdelay(1);

	}



	/* Would it be better to replace the trap vector here? */



	if (cpumask_weight(&cpus_in_crash) >= ncpus) {

	if (atomic_read(&cpus_in_crash) >= ncpus) {

		printk(KERN_EMERG "IPI complete\n");

		return;

	}



	printk(KERN_EMERG "ERROR: %d cpu(s) not responding\n",

		ncpus - cpumask_weight(&cpus_in_crash));

		ncpus - atomic_read(&cpus_in_crash));



	/*

	 * If we have a panic timeout set then we can't wait indefinitely
@@ -155,10 +161,10 @@ static void crash_kexec_prepare_cpus(int cpu) 
		 * crash code again. We need to reset cpus_in_crash so we

		 * wait for everyone to do this.

		 */

		cpus_in_crash = CPU_MASK_NONE;

		atomic_set(&cpus_in_crash, 0);

		smp_mb();



		while (cpumask_weight(&cpus_in_crash) < ncpus)

		while (atomic_read(&cpus_in_crash) < ncpus)

			cpu_relax();

	}
@@ -316,7 +322,6 @@ void default_machine_crash_shutdown(struct pt_regs *regs) 
	 * such that another IPI will not be sent.

	 */

	crashing_cpu = smp_processor_id();

	crash_save_cpu(regs, crashing_cpu);



	/*

	 * If we came in via system reset, wait a while for the secondary
@@ -326,7 +331,11 @@ void default_machine_crash_shutdown(struct pt_regs *regs) 
		mdelay(PRIMARY_TIMEOUT);



	crash_kexec_prepare_cpus(crashing_cpu);

	cpumask_set_cpu(crashing_cpu, &cpus_in_crash);



	crash_save_cpu(regs, crashing_cpu);



	time_to_dump = 1;



	crash_kexec_wait_realmode(crashing_cpu);



	machine_kexec_mask_interrupts();