Commit 8d539b84 authored by Douglas Anderson's avatar Douglas Anderson Committed by Andrew Morton
Browse files

nmi_backtrace: allow excluding an arbitrary CPU 

The APIs that allow backtracing across CPUs have always had a way to
exclude the current CPU.  This convenience means callers didn't need to
find a place to allocate a CPU mask just to handle the common case.

Let's extend the API to take a CPU ID to exclude instead of just a
boolean.  This isn't any more complex for the API to handle and allows the
hardlockup detector to exclude a different CPU (the one it already did a
trace for) without needing to find space for a CPU mask.

Arguably, this new API also encourages safer behavior.  Specifically if
the caller wants to avoid tracing the current CPU (maybe because they
already traced the current CPU) this makes it more obvious to the caller
that they need to make sure that the current CPU ID can't change.

[akpm@linux-foundation.org: fix trigger_allbutcpu_cpu_backtrace() stub]
Link: https://lkml.kernel.org/r/20230804065935.v4.1.Ia35521b91fc781368945161d7b28538f9996c182@changeid


Signed-off-by: default avatarDouglas Anderson <dianders@chromium.org>
Acked-by: default avatarMichal Hocko <mhocko@suse.com>
Cc: kernel test robot <lkp@intel.com>
Cc: Lecopzer Chen <lecopzer.chen@mediatek.com>
Cc: Petr Mladek <pmladek@suse.com>
Cc: Pingfan Liu <kernelfans@gmail.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent 3c9d017c

arch/arm/include/asm/irq.h

+1 −1
Original line number Diff line number Diff line
@@ -32,7 +32,7 @@ void handle_IRQ(unsigned int, struct pt_regs *); 
#include <linux/cpumask.h>



extern void arch_trigger_cpumask_backtrace(const cpumask_t *mask,

					   bool exclude_self);

					   int exclude_cpu);

#define arch_trigger_cpumask_backtrace arch_trigger_cpumask_backtrace

#endif

arch/arm/kernel/smp.c

+2 −2
Original line number Diff line number Diff line
@@ -846,7 +846,7 @@ static void raise_nmi(cpumask_t *mask) 
	__ipi_send_mask(ipi_desc[IPI_CPU_BACKTRACE], mask);

}



void arch_trigger_cpumask_backtrace(const cpumask_t *mask, bool exclude_self)

void arch_trigger_cpumask_backtrace(const cpumask_t *mask, int exclude_cpu)

{

	nmi_trigger_cpumask_backtrace(mask, exclude_self, raise_nmi);

	nmi_trigger_cpumask_backtrace(mask, exclude_cpu, raise_nmi);

}

arch/loongarch/include/asm/irq.h

+1 −1
Original line number Diff line number Diff line
@@ -40,7 +40,7 @@ void spurious_interrupt(void); 
#define NR_IRQS_LEGACY 16



#define arch_trigger_cpumask_backtrace arch_trigger_cpumask_backtrace

void arch_trigger_cpumask_backtrace(const struct cpumask *mask, bool exclude_self);

void arch_trigger_cpumask_backtrace(const struct cpumask *mask, int exclude_cpu);



#define MAX_IO_PICS 2

#define NR_IRQS	(64 + (256 * MAX_IO_PICS))

arch/loongarch/kernel/process.c

+2 −2
Original line number Diff line number Diff line
@@ -345,9 +345,9 @@ static void raise_backtrace(cpumask_t *mask) 
	}

}



void arch_trigger_cpumask_backtrace(const cpumask_t *mask, bool exclude_self)

void arch_trigger_cpumask_backtrace(const cpumask_t *mask, int exclude_cpu)

{

	nmi_trigger_cpumask_backtrace(mask, exclude_self, raise_backtrace);

	nmi_trigger_cpumask_backtrace(mask, exclude_cpu, raise_backtrace);

}



#ifdef CONFIG_64BIT

arch/mips/include/asm/irq.h

+1 −1
Original line number Diff line number Diff line
@@ -77,7 +77,7 @@ extern int cp0_fdc_irq; 
extern int get_c0_fdc_int(void);



void arch_trigger_cpumask_backtrace(const struct cpumask *mask,

				    bool exclude_self);

				    int exclude_cpu);

#define arch_trigger_cpumask_backtrace arch_trigger_cpumask_backtrace



#endif /* _ASM_IRQ_H */