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Commit 8f47b187 authored by Thomas Gleixner's avatar Thomas Gleixner Committed by Ingo Molnar
Browse files

sched: Add better debug output for might_sleep() 



might_sleep() can tell us where interrupts have been disabled, but we
have no idea what disabled preemption. Add some debug infrastructure.

Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Signed-off-by: default avatarSebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: default avatarPeter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/1391803122-4425-4-git-send-email-bigeasy@linutronix.de


Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent db273be2

include/linux/sched.h

+3 −0
Original line number Diff line number Diff line
@@ -1463,6 +1463,9 @@ struct task_struct { 
	struct mutex perf_event_mutex;

	struct list_head perf_event_list;

#endif

#ifdef CONFIG_DEBUG_PREEMPT

	unsigned long preempt_disable_ip;

#endif

#ifdef CONFIG_NUMA

	struct mempolicy *mempolicy;	/* Protected by alloc_lock */

	short il_next;

kernel/sched/core.c

+21 −2
Original line number Diff line number Diff line
@@ -2501,8 +2501,13 @@ void __kprobes preempt_count_add(int val) 
	DEBUG_LOCKS_WARN_ON((preempt_count() & PREEMPT_MASK) >=

				PREEMPT_MASK - 10);

#endif

	if (preempt_count() == val)

		trace_preempt_off(CALLER_ADDR0, get_parent_ip(CALLER_ADDR1));

	if (preempt_count() == val) {

		unsigned long ip = get_parent_ip(CALLER_ADDR1);

#ifdef CONFIG_DEBUG_PREEMPT

		current->preempt_disable_ip = ip;

#endif

		trace_preempt_off(CALLER_ADDR0, ip);

	}

}

EXPORT_SYMBOL(preempt_count_add);
@@ -2545,6 +2550,13 @@ static noinline void __schedule_bug(struct task_struct *prev) 
	print_modules();

	if (irqs_disabled())

		print_irqtrace_events(prev);

#ifdef CONFIG_DEBUG_PREEMPT

	if (in_atomic_preempt_off()) {

		pr_err("Preemption disabled at:");

		print_ip_sym(current->preempt_disable_ip);

		pr_cont("\n");

	}

#endif

	dump_stack();

	add_taint(TAINT_WARN, LOCKDEP_STILL_OK);

}
@@ -6946,6 +6958,13 @@ void __might_sleep(const char *file, int line, int preempt_offset) 
	debug_show_held_locks(current);

	if (irqs_disabled())

		print_irqtrace_events(current);

#ifdef CONFIG_DEBUG_PREEMPT

	if (!preempt_count_equals(preempt_offset)) {

		pr_err("Preemption disabled at:");

		print_ip_sym(current->preempt_disable_ip);

		pr_cont("\n");

	}

#endif

	dump_stack();

}

EXPORT_SYMBOL(__might_sleep);