panic: change nmi_panic from macro to function (ebc41f20) · Commits · 戴 / test

Commit ("panic, x86: Fix re-entrance problem due to panic on NMI") and commit ("panic, x86: Allow CPUs to save registers even if looping in NMI context") introduced nmi_panic() which prevents concurrent/recursive execution of panic(). It also saves registers for the crash dump on x86. However, there are some cases where NMI handlers still use panic(). This patch set partially replaces them with nmi_panic() in those cases. Even this patchset is applied, some NMI or similar handlers (e.g. MCE handler) continue to use panic(). This is because I can't test them well and actual problems won't happen. For example, the possibility that normal panic and panic on MCE happen simultaneously is very low. This patch (of 3): Convert nmi_panic() to a proper function and export it instead of exporting internal implementation details to modules, for obvious reasons. Signed-off-by:

Hidehiro Kawai <hidehiro.kawai.ez@hitachi.com> Acked-by:

Borislav Petkov <bp@suse.de> Acked-by:

Michal Nazarewicz <mina86@mina86.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Rasmus Villemoes <linux@rasmusvillemoes.dk> Cc: Nicolas Iooss <nicolas.iooss_linux@m4x.org> Cc: Javi Merino <javi.merino@arm.com> Cc: Gobinda Charan Maji <gobinda.cemk07@gmail.com> Cc: "Steven Rostedt (Red Hat)" <rostedt@goodmis.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Vitaly Kuznetsov <vkuznets@redhat.com> Cc: HATAYAMA Daisuke <d.hatayama@jp.fujitsu.com> Cc: Tejun Heo <tj@kernel.org> Signed-off-by:

Andrew Morton <akpm@linux-foundation.org> Signed-off-by:

Linus Torvalds <torvalds@linux-foundation.org>

include/linux/kernel.h

+1 −20

Original line number	Diff line number	Diff line
		@@ -255,7 +255,7 @@ extern long (*panic_blink)(int state);
		__printf(1, 2)
		void panic(const char *fmt, ...)
		__noreturn __cold;
		void nmi_panic_self_stop(struct pt_regs *);
		void nmi_panic(struct pt_regs regs, const char msg);
		extern void oops_enter(void);
		extern void oops_exit(void);
		void print_oops_end_marker(void);
		@@ -456,25 +456,6 @@ extern bool crash_kexec_post_notifiers;
		extern atomic_t panic_cpu;
		#define PANIC_CPU_INVALID -1

		/*
		* A variant of panic() called from NMI context. We return if we've already
		* panicked on this CPU. If another CPU already panicked, loop in
		* nmi_panic_self_stop() which can provide architecture dependent code such
		* as saving register state for crash dump.
		*/
		#define nmi_panic(regs, fmt, ...) \
		do { \
		int old_cpu, cpu; \
		\
		cpu = raw_smp_processor_id(); \
		old_cpu = atomic_cmpxchg(&panic_cpu, PANIC_CPU_INVALID, cpu); \
		\
		if (old_cpu == PANIC_CPU_INVALID) \
		panic(fmt, ##__VA_ARGS__); \
		else if (old_cpu != cpu) \
		nmi_panic_self_stop(regs); \
		} while (0)

		/*
		* Only to be used by arch init code. If the user over-wrote the default
		* CONFIG_PANIC_TIMEOUT, honor it.

kernel/panic.c

+20 −0

Original line number	Diff line number	Diff line
		@@ -73,6 +73,26 @@ void __weak nmi_panic_self_stop(struct pt_regs *regs)

		atomic_t panic_cpu = ATOMIC_INIT(PANIC_CPU_INVALID);

		/*
		* A variant of panic() called from NMI context. We return if we've already
		* panicked on this CPU. If another CPU already panicked, loop in
		* nmi_panic_self_stop() which can provide architecture dependent code such
		* as saving register state for crash dump.
		*/
		void nmi_panic(struct pt_regs regs, const char msg)
		{
		int old_cpu, cpu;

		cpu = raw_smp_processor_id();
		old_cpu = atomic_cmpxchg(&panic_cpu, PANIC_CPU_INVALID, cpu);

		if (old_cpu == PANIC_CPU_INVALID)
		panic("%s", msg);
		else if (old_cpu != cpu)
		nmi_panic_self_stop(regs);
		}
		EXPORT_SYMBOL(nmi_panic);

		/**
		* panic - halt the system
		* @fmt: The text string to print

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