Commit c3bc8fd6 authored by Joel Fernandes (Google)'s avatar Joel Fernandes (Google) Committed by Steven Rostedt (VMware)
Browse files

tracing: Centralize preemptirq tracepoints and unify their usage 

This patch detaches the preemptirq tracepoints from the tracers and
keeps it separate.

Advantages:
* Lockdep and irqsoff event can now run in parallel since they no longer
have their own calls.

* This unifies the usecase of adding hooks to an irqsoff and irqson
event, and a preemptoff and preempton event.
  3 users of the events exist:
  - Lockdep
  - irqsoff and preemptoff tracers
  - irqs and preempt trace events

The unification cleans up several ifdefs and makes the code in preempt
tracer and irqsoff tracers simpler. It gets rid of all the horrific
ifdeferry around PROVE_LOCKING and makes configuration of the different
users of the tracepoints more easy and understandable. It also gets rid
of the time_* function calls from the lockdep hooks used to call into
the preemptirq tracer which is not needed anymore. The negative delta in
lines of code in this patch is quite large too.

In the patch we introduce a new CONFIG option PREEMPTIRQ_TRACEPOINTS
as a single point for registering probes onto the tracepoints. With
this,
the web of config options for preempt/irq toggle tracepoints and its
users becomes:

 PREEMPT_TRACER   PREEMPTIRQ_EVENTS  IRQSOFF_TRACER PROVE_LOCKING
       |                 |     \         |           |
       \    (selects)    /      \        \ (selects) /
      TRACE_PREEMPT_TOGGLE       ----> TRACE_IRQFLAGS
                      \                  /
                       \ (depends on)   /
                     PREEMPTIRQ_TRACEPOINTS

Other than the performance tests mentioned in the previous patch, I also
ran the locking API test suite. I verified that all tests cases are
passing.

I also injected issues by not registering lockdep probes onto the
tracepoints and I see failures to confirm that the probes are indeed
working.

This series + lockdep probes not registered (just to inject errors):
[    0.000000]      hard-irqs-on + irq-safe-A/21:  ok  |  ok  |  ok  |
[    0.000000]      soft-irqs-on + irq-safe-A/21:  ok  |  ok  |  ok  |
[    0.000000]        sirq-safe-A => hirqs-on/12:FAILED|FAILED|  ok  |
[    0.000000]        sirq-safe-A => hirqs-on/21:FAILED|FAILED|  ok  |
[    0.000000]          hard-safe-A + irqs-on/12:FAILED|FAILED|  ok  |
[    0.000000]          soft-safe-A + irqs-on/12:FAILED|FAILED|  ok  |
[    0.000000]          hard-safe-A + irqs-on/21:FAILED|FAILED|  ok  |
[    0.000000]          soft-safe-A + irqs-on/21:FAILED|FAILED|  ok  |
[    0.000000]     hard-safe-A + unsafe-B #1/123:  ok  |  ok  |  ok  |
[    0.000000]     soft-safe-A + unsafe-B #1/123:  ok  |  ok  |  ok  |

With this series + lockdep probes registered, all locking tests pass:

[    0.000000]      hard-irqs-on + irq-safe-A/21:  ok  |  ok  |  ok  |
[    0.000000]      soft-irqs-on + irq-safe-A/21:  ok  |  ok  |  ok  |
[    0.000000]        sirq-safe-A => hirqs-on/12:  ok  |  ok  |  ok  |
[    0.000000]        sirq-safe-A => hirqs-on/21:  ok  |  ok  |  ok  |
[    0.000000]          hard-safe-A + irqs-on/12:  ok  |  ok  |  ok  |
[    0.000000]          soft-safe-A + irqs-on/12:  ok  |  ok  |  ok  |
[    0.000000]          hard-safe-A + irqs-on/21:  ok  |  ok  |  ok  |
[    0.000000]          soft-safe-A + irqs-on/21:  ok  |  ok  |  ok  |
[    0.000000]     hard-safe-A + unsafe-B #1/123:  ok  |  ok  |  ok  |
[    0.000000]     soft-safe-A + unsafe-B #1/123:  ok  |  ok  |  ok  |

Link: http://lkml.kernel.org/r/20180730222423.196630-4-joel@joelfernandes.org



Acked-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: default avatarNamhyung Kim <namhyung@kernel.org>
Signed-off-by: default avatarJoel Fernandes (Google) <joel@joelfernandes.org>
Signed-off-by: default avatarSteven Rostedt (VMware) <rostedt@goodmis.org>
parent e6753f23

include/linux/ftrace.h

+1 −10
Original line number Diff line number Diff line
@@ -701,16 +701,7 @@ static inline unsigned long get_lock_parent_ip(void) 
	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);

#else

  static inline void time_hardirqs_on(unsigned long a0, unsigned long a1) { }

  static inline void time_hardirqs_off(unsigned long a0, unsigned long a1) { }

#endif



#if defined(CONFIG_PREEMPT_TRACER) || \

	(defined(CONFIG_DEBUG_PREEMPT) && defined(CONFIG_PREEMPTIRQ_EVENTS))

#ifdef CONFIG_TRACE_PREEMPT_TOGGLE

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

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

#else

include/linux/irqflags.h

+8 −3
Original line number Diff line number Diff line
@@ -15,9 +15,16 @@ 
#include <linux/typecheck.h>

#include <asm/irqflags.h>



#ifdef CONFIG_TRACE_IRQFLAGS

/* Currently trace_softirqs_on/off is used only by lockdep */

#ifdef CONFIG_PROVE_LOCKING

  extern void trace_softirqs_on(unsigned long ip);

  extern void trace_softirqs_off(unsigned long ip);

#else

# define trace_softirqs_on(ip)	do { } while (0)

# define trace_softirqs_off(ip)	do { } while (0)

#endif



#ifdef CONFIG_TRACE_IRQFLAGS

  extern void trace_hardirqs_on(void);

  extern void trace_hardirqs_off(void);

# define trace_hardirq_context(p)	((p)->hardirq_context)
@@ -43,8 +50,6 @@ do { \ 
#else

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

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

# define trace_softirqs_on(ip)		do { } while (0)

# define trace_softirqs_off(ip)		do { } while (0)

# define trace_hardirq_context(p)	0

# define trace_softirq_context(p)	0

# define trace_hardirqs_enabled(p)	0

include/linux/lockdep.h

+5 −3
Original line number Diff line number Diff line
@@ -266,7 +266,8 @@ struct held_lock { 
/*

 * Initialization, self-test and debugging-output methods:

 */

extern void lockdep_info(void);

extern void lockdep_init(void);

extern void lockdep_init_early(void);

extern void lockdep_reset(void);

extern void lockdep_reset_lock(struct lockdep_map *lock);

extern void lockdep_free_key_range(void *start, unsigned long size);
@@ -406,7 +407,8 @@ static inline void lockdep_on(void) 
# define lock_downgrade(l, i)			do { } while (0)

# define lock_set_class(l, n, k, s, i)		do { } while (0)

# define lock_set_subclass(l, s, i)		do { } while (0)

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

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

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

# define lockdep_init_map(lock, name, key, sub) \

		do { (void)(name); (void)(key); } while (0)

# define lockdep_set_class(lock, key)		do { (void)(key); } while (0)
@@ -532,7 +534,7 @@ do { \ 


#endif /* CONFIG_LOCKDEP */



#ifdef CONFIG_TRACE_IRQFLAGS

#ifdef CONFIG_PROVE_LOCKING

extern void print_irqtrace_events(struct task_struct *curr);

#else

static inline void print_irqtrace_events(struct task_struct *curr)

include/linux/preempt.h

+1 −1
Original line number Diff line number Diff line
@@ -150,7 +150,7 @@ 
 */

#define in_atomic_preempt_off() (preempt_count() != PREEMPT_DISABLE_OFFSET)



#if defined(CONFIG_DEBUG_PREEMPT) || defined(CONFIG_PREEMPT_TRACER)

#if defined(CONFIG_DEBUG_PREEMPT) || defined(CONFIG_TRACE_PREEMPT_TOGGLE)

extern void preempt_count_add(int val);

extern void preempt_count_sub(int val);

#define preempt_count_dec_and_test() \

include/trace/events/preemptirq.h

+14 −9
Original line number Diff line number Diff line 
#ifdef CONFIG_PREEMPTIRQ_EVENTS

#ifdef CONFIG_PREEMPTIRQ_TRACEPOINTS



#undef TRACE_SYSTEM

#define TRACE_SYSTEM preemptirq
@@ -32,7 +32,7 @@ DECLARE_EVENT_CLASS(preemptirq_template, 
		  (void *)((unsigned long)(_stext) + __entry->parent_offs))

);



#ifndef CONFIG_PROVE_LOCKING

#ifdef CONFIG_TRACE_IRQFLAGS

DEFINE_EVENT(preemptirq_template, irq_disable,

	     TP_PROTO(unsigned long ip, unsigned long parent_ip),

	     TP_ARGS(ip, parent_ip));
@@ -40,9 +40,14 @@ DEFINE_EVENT(preemptirq_template, irq_disable, 
DEFINE_EVENT(preemptirq_template, irq_enable,

	     TP_PROTO(unsigned long ip, unsigned long parent_ip),

	     TP_ARGS(ip, parent_ip));

#else

#define trace_irq_enable(...)

#define trace_irq_disable(...)

#define trace_irq_enable_rcuidle(...)

#define trace_irq_disable_rcuidle(...)

#endif



#ifdef CONFIG_DEBUG_PREEMPT

#ifdef CONFIG_TRACE_PREEMPT_TOGGLE

DEFINE_EVENT(preemptirq_template, preempt_disable,

	     TP_PROTO(unsigned long ip, unsigned long parent_ip),

	     TP_ARGS(ip, parent_ip));
@@ -50,22 +55,22 @@ DEFINE_EVENT(preemptirq_template, preempt_disable, 
DEFINE_EVENT(preemptirq_template, preempt_enable,

	     TP_PROTO(unsigned long ip, unsigned long parent_ip),

	     TP_ARGS(ip, parent_ip));

#else

#define trace_preempt_enable(...)

#define trace_preempt_disable(...)

#define trace_preempt_enable_rcuidle(...)

#define trace_preempt_disable_rcuidle(...)

#endif



#endif /* _TRACE_PREEMPTIRQ_H */



#include <trace/define_trace.h>



#endif /* !CONFIG_PREEMPTIRQ_EVENTS */



#if !defined(CONFIG_PREEMPTIRQ_EVENTS) || defined(CONFIG_PROVE_LOCKING)

#else /* !CONFIG_PREEMPTIRQ_TRACEPOINTS */

#define trace_irq_enable(...)

#define trace_irq_disable(...)

#define trace_irq_enable_rcuidle(...)

#define trace_irq_disable_rcuidle(...)

#endif



#if !defined(CONFIG_PREEMPTIRQ_EVENTS) || !defined(CONFIG_DEBUG_PREEMPT)

#define trace_preempt_enable(...)

#define trace_preempt_disable(...)

#define trace_preempt_enable_rcuidle(...)

CRA Git | Maintained and supported by SUSTech CRA and CCSE