Commit f3aca3d0 authored by Aaron Tomlin's avatar Aaron Tomlin Committed by Linus Torvalds
Browse files

nmi: provide the option to issue an NMI back trace to every cpu but current 



Sometimes it is preferred not to use the trigger_all_cpu_backtrace()
routine when one wants to avoid capturing a back trace for current.  For
instance if one was previously captured recently.

This patch provides a new routine namely
trigger_allbutself_cpu_backtrace() which offers the flexibility to issue
an NMI to every cpu but current and capture a back trace accordingly.

Patch x86 and sparc to support new routine.

[dzickus@redhat.com: add stub in #else clause]
[dzickus@redhat.com: don't print message in single processor case, wrap with get/put_cpu based on Oleg's suggestion]
[sfr@canb.auug.org.au: undo C99ism]
Signed-off-by: default avatarAaron Tomlin <atomlin@redhat.com>
Signed-off-by: default avatarDon Zickus <dzickus@redhat.com>
Acked-by: default avatarDavid S. Miller <davem@davemloft.net>
Cc: Mateusz Guzik <mguzik@redhat.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: default avatarStephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 88e15ce4

arch/sparc/include/asm/irq_64.h

+1 −1
Original line number Diff line number Diff line
@@ -89,7 +89,7 @@ static inline unsigned long get_softint(void) 
	return retval;

}



void arch_trigger_all_cpu_backtrace(void);

void arch_trigger_all_cpu_backtrace(bool);

#define arch_trigger_all_cpu_backtrace arch_trigger_all_cpu_backtrace



extern void *hardirq_stack[NR_CPUS];

arch/sparc/kernel/process_64.c

+12 −6
Original line number Diff line number Diff line
@@ -239,7 +239,7 @@ static void __global_reg_poll(struct global_reg_snapshot *gp) 
	}

}



void arch_trigger_all_cpu_backtrace(void)

void arch_trigger_all_cpu_backtrace(bool include_self)

{

	struct thread_info *tp = current_thread_info();

	struct pt_regs *regs = get_irq_regs();
@@ -251,16 +251,22 @@ void arch_trigger_all_cpu_backtrace(void) 


	spin_lock_irqsave(&global_cpu_snapshot_lock, flags);



	memset(global_cpu_snapshot, 0, sizeof(global_cpu_snapshot));



	this_cpu = raw_smp_processor_id();



	memset(global_cpu_snapshot, 0, sizeof(global_cpu_snapshot));



	if (include_self)

		__global_reg_self(tp, regs, this_cpu);



	smp_fetch_global_regs();



	for_each_online_cpu(cpu) {

		struct global_reg_snapshot *gp = &global_cpu_snapshot[cpu].reg;

		struct global_reg_snapshot *gp;



		if (!include_self && cpu == this_cpu)

			continue;



		gp = &global_cpu_snapshot[cpu].reg;



		__global_reg_poll(gp);
@@ -292,7 +298,7 @@ void arch_trigger_all_cpu_backtrace(void) 


static void sysrq_handle_globreg(int key)

{

	arch_trigger_all_cpu_backtrace();

	arch_trigger_all_cpu_backtrace(true);

}



static struct sysrq_key_op sparc_globalreg_op = {

arch/x86/include/asm/irq.h

+1 −1
Original line number Diff line number Diff line
@@ -43,7 +43,7 @@ extern int vector_used_by_percpu_irq(unsigned int vector); 
extern void init_ISA_irqs(void);



#ifdef CONFIG_X86_LOCAL_APIC

void arch_trigger_all_cpu_backtrace(void);

void arch_trigger_all_cpu_backtrace(bool);

#define arch_trigger_all_cpu_backtrace arch_trigger_all_cpu_backtrace

#endif

arch/x86/kernel/apic/hw_nmi.c

+14 −4
Original line number Diff line number Diff line
@@ -33,31 +33,41 @@ static DECLARE_BITMAP(backtrace_mask, NR_CPUS) __read_mostly; 
/* "in progress" flag of arch_trigger_all_cpu_backtrace */

static unsigned long backtrace_flag;



void arch_trigger_all_cpu_backtrace(void)

void arch_trigger_all_cpu_backtrace(bool include_self)

{

	int i;

	int cpu = get_cpu();



	if (test_and_set_bit(0, &backtrace_flag))

	if (test_and_set_bit(0, &backtrace_flag)) {

		/*

		 * If there is already a trigger_all_cpu_backtrace() in progress

		 * (backtrace_flag == 1), don't output double cpu dump infos.

		 */

		put_cpu();

		return;

	}



	cpumask_copy(to_cpumask(backtrace_mask), cpu_online_mask);

	if (!include_self)

		cpumask_clear_cpu(cpu, to_cpumask(backtrace_mask));



	printk(KERN_INFO "sending NMI to all CPUs:\n");

	apic->send_IPI_all(NMI_VECTOR);

	if (!cpumask_empty(to_cpumask(backtrace_mask))) {

		pr_info("sending NMI to %s CPUs:\n",

			(include_self ? "all" : "other"));

		apic->send_IPI_mask(to_cpumask(backtrace_mask), NMI_VECTOR);

	}



	/* Wait for up to 10 seconds for all CPUs to do the backtrace */

	for (i = 0; i < 10 * 1000; i++) {

		if (cpumask_empty(to_cpumask(backtrace_mask)))

			break;

		mdelay(1);

		touch_softlockup_watchdog();

	}



	clear_bit(0, &backtrace_flag);

	smp_mb__after_atomic();

	put_cpu();

}



static int

include/linux/nmi.h

+10 −1
Original line number Diff line number Diff line
@@ -32,15 +32,24 @@ static inline void touch_nmi_watchdog(void) 
#ifdef arch_trigger_all_cpu_backtrace

static inline bool trigger_all_cpu_backtrace(void)

{

	arch_trigger_all_cpu_backtrace();

	arch_trigger_all_cpu_backtrace(true);



	return true;

}

static inline bool trigger_allbutself_cpu_backtrace(void)

{

	arch_trigger_all_cpu_backtrace(false);

	return true;

}

#else

static inline bool trigger_all_cpu_backtrace(void)

{

	return false;

}

static inline bool trigger_allbutself_cpu_backtrace(void)

{

	return false;

}

#endif



#ifdef CONFIG_LOCKUP_DETECTOR

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