Commit 3117df04 authored by Ingo Molnar's avatar Ingo Molnar Committed by Linus Torvalds
Browse files

[PATCH] lockdep: print irq-trace info on asserts 



When we print an assert due to scheduling-in-atomic bugs, and if lockdep
is enabled, then the IRQ tracing information of lockdep can be printed
to pinpoint the code location that disabled interrupts. This saved me
quite a bit of debugging time in cases where the backtrace did not
identify the irq-disabling site well enough.

Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent 27c3b232

include/linux/lockdep.h

+13 −3
Original line number Diff line number Diff line
@@ -281,15 +281,25 @@ struct lock_class_key { }; 
#if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_GENERIC_HARDIRQS)

extern void early_init_irq_lock_class(void);

#else

# define early_init_irq_lock_class()		do { } while (0)

static inline void early_init_irq_lock_class(void)

{

}

#endif



#ifdef CONFIG_TRACE_IRQFLAGS

extern void early_boot_irqs_off(void);

extern void early_boot_irqs_on(void);

extern void print_irqtrace_events(struct task_struct *curr);

#else

# define early_boot_irqs_off()			do { } while (0)

# define early_boot_irqs_on()			do { } while (0)

static inline void early_boot_irqs_off(void)

{

}

static inline void early_boot_irqs_on(void)

{

}

static inline void print_irqtrace_events(struct task_struct *curr)

{

}

#endif



/*

kernel/lockdep.c

+1 −5
Original line number Diff line number Diff line
@@ -1447,7 +1447,7 @@ check_usage_backwards(struct task_struct *curr, struct held_lock *this, 
	return print_irq_inversion_bug(curr, backwards_match, this, 0, irqclass);

}



static inline void print_irqtrace_events(struct task_struct *curr)

void print_irqtrace_events(struct task_struct *curr)

{

	printk("irq event stamp: %u\n", curr->irq_events);

	printk("hardirqs last  enabled at (%u): ", curr->hardirq_enable_event);
@@ -1460,10 +1460,6 @@ static inline void print_irqtrace_events(struct task_struct *curr) 
	print_ip_sym(curr->softirq_disable_ip);

}



#else

static inline void print_irqtrace_events(struct task_struct *curr)

{

}

#endif



static int

kernel/sched.c

+4 −0
Original line number Diff line number Diff line
@@ -3429,6 +3429,8 @@ asmlinkage void __sched schedule(void) 
			"%s/0x%08x/%d\n",

			current->comm, preempt_count(), current->pid);

		debug_show_held_locks(current);

		if (irqs_disabled())

			print_irqtrace_events(current);

		dump_stack();

	}

	profile_hit(SCHED_PROFILING, __builtin_return_address(0));
@@ -6977,6 +6979,8 @@ void __might_sleep(char *file, int line) 
		printk("in_atomic():%d, irqs_disabled():%d\n",

			in_atomic(), irqs_disabled());

		debug_show_held_locks(current);

		if (irqs_disabled())

			print_irqtrace_events(current);

		dump_stack();

	}

#endif

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