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MIPS: Add arch_trigger_all_cpu_backtrace() function
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Currently, arch_trigger_all_cpu_backtrace() is defined in only x86 and
sparc which have an NMI.  But in case of softlockup, it could be possible
to dump backtrace of all cpus. and this could be helpful for debugging.

for example, if system has 2 cpus.

	CPU 0				CPU 1
 acquire read_lock()

				try to do write_lock()

 ,,,
 missing read_unlock()

In this case, softlockup will occur becasuse CPU 0 does not call
read_unlock().  And dump_stack() print only backtrace for "CPU 0". If
CPU1's backtrace is printed it's very helpful.

[ralf@linux-mips.org: Fixed whitespace and formatting issues.]

Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Cc: linux-mips@linux-mips.org
Cc: linux-kernel@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/8200/
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EunBongSong authored and ralfbaechle committed Nov 24, 2014
1 parent 635c990 commit 856839b
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3 changes: 3 additions & 0 deletions arch/mips/include/asm/irq.h
Original file line number Diff line number Diff line change
Expand Up @@ -48,4 +48,7 @@ extern int cp0_compare_irq;
extern int cp0_compare_irq_shift;
extern int cp0_perfcount_irq;

void arch_trigger_all_cpu_backtrace(bool);
#define arch_trigger_all_cpu_backtrace arch_trigger_all_cpu_backtrace

#endif /* _ASM_IRQ_H */
18 changes: 18 additions & 0 deletions arch/mips/kernel/process.c
Original file line number Diff line number Diff line change
Expand Up @@ -42,6 +42,7 @@
#include <asm/isadep.h>
#include <asm/inst.h>
#include <asm/stacktrace.h>
#include <asm/irq_regs.h>

#ifdef CONFIG_HOTPLUG_CPU
void arch_cpu_idle_dead(void)
Expand Down Expand Up @@ -532,3 +533,20 @@ unsigned long arch_align_stack(unsigned long sp)

return sp & ALMASK;
}

static void arch_dump_stack(void *info)
{
struct pt_regs *regs;

regs = get_irq_regs();

if (regs)
show_regs(regs);

dump_stack();
}

void arch_trigger_all_cpu_backtrace(bool include_self)
{
smp_call_function(arch_dump_stack, NULL, 1);
}

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