Commit f904f582 authored by Sebastian Andrzej Siewior's avatar Sebastian Andrzej Siewior Committed by Ingo Molnar
Browse files

sched/debug: Fix preempt_disable_ip recording for preempt_disable() 



The preempt_disable() invokes preempt_count_add() which saves the caller
in ->preempt_disable_ip. It uses CALLER_ADDR1 which does not look for
its caller but for the parent of the caller. Which means we get the correct
caller for something like spin_lock() unless the architectures inlines
those invocations. It is always wrong for preempt_disable() or
local_bh_disable().

This patch makes the function get_lock_parent_ip() which tries
CALLER_ADDR0,1,2 if the former is a locking function.
This seems to record the preempt_disable() caller properly for
preempt_disable() itself as well as for get_cpu_var() or
local_bh_disable().

Steven asked for the get_parent_ip() -> get_lock_parent_ip() rename.

Signed-off-by: default avatarSebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20160226135456.GB18244@linutronix.de


Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent ff9a9b4c

include/linux/ftrace.h

+12 −0
Original line number Diff line number Diff line
@@ -713,6 +713,18 @@ static inline void __ftrace_enabled_restore(int enabled) 
#define CALLER_ADDR5 ((unsigned long)ftrace_return_address(5))

#define CALLER_ADDR6 ((unsigned long)ftrace_return_address(6))



static inline unsigned long get_lock_parent_ip(void)

{

	unsigned long addr = CALLER_ADDR0;



	if (!in_lock_functions(addr))

		return addr;

	addr = CALLER_ADDR1;

	if (!in_lock_functions(addr))

		return addr;

	return CALLER_ADDR2;

}



#ifdef CONFIG_IRQSOFF_TRACER

  extern void time_hardirqs_on(unsigned long a0, unsigned long a1);

  extern void time_hardirqs_off(unsigned long a0, unsigned long a1);

include/linux/sched.h

+0 −2
Original line number Diff line number Diff line
@@ -182,8 +182,6 @@ extern void update_cpu_load_nohz(int active); 
static inline void update_cpu_load_nohz(int active) { }

#endif



extern unsigned long get_parent_ip(unsigned long addr);



extern void dump_cpu_task(int cpu);



struct seq_file;

kernel/sched/core.c

+2 −12
Original line number Diff line number Diff line
@@ -2946,16 +2946,6 @@ u64 scheduler_tick_max_deferment(void) 
}

#endif



notrace unsigned long get_parent_ip(unsigned long addr)

{

	if (in_lock_functions(addr)) {

		addr = CALLER_ADDR2;

		if (in_lock_functions(addr))

			addr = CALLER_ADDR3;

	}

	return addr;

}



#if defined(CONFIG_PREEMPT) && (defined(CONFIG_DEBUG_PREEMPT) || \

				defined(CONFIG_PREEMPT_TRACER))
@@ -2977,7 +2967,7 @@ void preempt_count_add(int val) 
				PREEMPT_MASK - 10);

#endif

	if (preempt_count() == val) {

		unsigned long ip = get_parent_ip(CALLER_ADDR1);

		unsigned long ip = get_lock_parent_ip();

#ifdef CONFIG_DEBUG_PREEMPT

		current->preempt_disable_ip = ip;

#endif
@@ -3004,7 +2994,7 @@ void preempt_count_sub(int val) 
#endif



	if (preempt_count() == val)

		trace_preempt_on(CALLER_ADDR0, get_parent_ip(CALLER_ADDR1));

		trace_preempt_on(CALLER_ADDR0, get_lock_parent_ip());

	__preempt_count_sub(val);

}

EXPORT_SYMBOL(preempt_count_sub);

kernel/softirq.c

+2 −2
Original line number Diff line number Diff line
@@ -116,9 +116,9 @@ void __local_bh_disable_ip(unsigned long ip, unsigned int cnt) 


	if (preempt_count() == cnt) {

#ifdef CONFIG_DEBUG_PREEMPT

		current->preempt_disable_ip = get_parent_ip(CALLER_ADDR1);

		current->preempt_disable_ip = get_lock_parent_ip();

#endif

		trace_preempt_off(CALLER_ADDR0, get_parent_ip(CALLER_ADDR1));

		trace_preempt_off(CALLER_ADDR0, get_lock_parent_ip());

	}

}

EXPORT_SYMBOL(__local_bh_disable_ip);

CRA Git | Maintained and supported by SUSTech CRA and CCSE