Commit 19193bca authored by Waiman Long's avatar Waiman Long Committed by Ingo Molnar
Browse files

locking/Kconfig: Restructure the lock debugging menu 



Two config options in the lock debugging menu that are probably the most
frequently used, as far as I am concerned, is the PROVE_LOCKING and
LOCK_STAT. From a UI perspective, they should be front and center. So
these two options are now moved to the top of the lock debugging menu.

The DEBUG_WW_MUTEX_SLOWPATH option is also added to the PROVE_LOCKING
umbrella.

Signed-off-by: default avatarWaiman Long <longman@redhat.com>
Acked-by: default avatarDavidlohr Bueso <dave@stgolabs.net>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1522445280-7767-4-git-send-email-longman@redhat.com


Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent f07cbebb

lib/Kconfig.debug

+68 −67
Original line number Diff line number Diff line
@@ -1039,6 +1039,74 @@ config LOCK_DEBUGGING_SUPPORT 
	depends on TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT

	default y



config PROVE_LOCKING

	bool "Lock debugging: prove locking correctness"

	depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT

	select LOCKDEP

	select DEBUG_SPINLOCK

	select DEBUG_MUTEXES

	select DEBUG_RT_MUTEXES if RT_MUTEXES

	select DEBUG_RWSEMS if RWSEM_SPIN_ON_OWNER

	select DEBUG_WW_MUTEX_SLOWPATH

	select DEBUG_LOCK_ALLOC

	select TRACE_IRQFLAGS

	default n

	help

	 This feature enables the kernel to prove that all locking

	 that occurs in the kernel runtime is mathematically

	 correct: that under no circumstance could an arbitrary (and

	 not yet triggered) combination of observed locking

	 sequences (on an arbitrary number of CPUs, running an

	 arbitrary number of tasks and interrupt contexts) cause a

	 deadlock.



	 In short, this feature enables the kernel to report locking

	 related deadlocks before they actually occur.



	 The proof does not depend on how hard and complex a

	 deadlock scenario would be to trigger: how many

	 participant CPUs, tasks and irq-contexts would be needed

	 for it to trigger. The proof also does not depend on

	 timing: if a race and a resulting deadlock is possible

	 theoretically (no matter how unlikely the race scenario

	 is), it will be proven so and will immediately be

	 reported by the kernel (once the event is observed that

	 makes the deadlock theoretically possible).



	 If a deadlock is impossible (i.e. the locking rules, as

	 observed by the kernel, are mathematically correct), the

	 kernel reports nothing.



	 NOTE: this feature can also be enabled for rwlocks, mutexes

	 and rwsems - in which case all dependencies between these

	 different locking variants are observed and mapped too, and

	 the proof of observed correctness is also maintained for an

	 arbitrary combination of these separate locking variants.



	 For more details, see Documentation/locking/lockdep-design.txt.



config LOCK_STAT

	bool "Lock usage statistics"

	depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT

	select LOCKDEP

	select DEBUG_SPINLOCK

	select DEBUG_MUTEXES

	select DEBUG_RT_MUTEXES if RT_MUTEXES

	select DEBUG_LOCK_ALLOC

	default n

	help

	 This feature enables tracking lock contention points



	 For more details, see Documentation/locking/lockstat.txt



	 This also enables lock events required by "perf lock",

	 subcommand of perf.

	 If you want to use "perf lock", you also need to turn on

	 CONFIG_EVENT_TRACING.



	 CONFIG_LOCK_STAT defines "contended" and "acquired" lock events.

	 (CONFIG_LOCKDEP defines "acquire" and "release" events.)



config DEBUG_RT_MUTEXES

	bool "RT Mutex debugging, deadlock detection"

	depends on DEBUG_KERNEL && RT_MUTEXES
@@ -1102,51 +1170,6 @@ config DEBUG_LOCK_ALLOC 
	 spin_lock_init()/mutex_init()/etc., or whether there is any lock

	 held during task exit.



config PROVE_LOCKING

	bool "Lock debugging: prove locking correctness"

	depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT

	select LOCKDEP

	select DEBUG_SPINLOCK

	select DEBUG_MUTEXES

	select DEBUG_RT_MUTEXES if RT_MUTEXES

	select DEBUG_RWSEMS if RWSEM_SPIN_ON_OWNER

	select DEBUG_LOCK_ALLOC

	select TRACE_IRQFLAGS

	default n

	help

	 This feature enables the kernel to prove that all locking

	 that occurs in the kernel runtime is mathematically

	 correct: that under no circumstance could an arbitrary (and

	 not yet triggered) combination of observed locking

	 sequences (on an arbitrary number of CPUs, running an

	 arbitrary number of tasks and interrupt contexts) cause a

	 deadlock.



	 In short, this feature enables the kernel to report locking

	 related deadlocks before they actually occur.



	 The proof does not depend on how hard and complex a

	 deadlock scenario would be to trigger: how many

	 participant CPUs, tasks and irq-contexts would be needed

	 for it to trigger. The proof also does not depend on

	 timing: if a race and a resulting deadlock is possible

	 theoretically (no matter how unlikely the race scenario

	 is), it will be proven so and will immediately be

	 reported by the kernel (once the event is observed that

	 makes the deadlock theoretically possible).



	 If a deadlock is impossible (i.e. the locking rules, as

	 observed by the kernel, are mathematically correct), the

	 kernel reports nothing.



	 NOTE: this feature can also be enabled for rwlocks, mutexes

	 and rwsems - in which case all dependencies between these

	 different locking variants are observed and mapped too, and

	 the proof of observed correctness is also maintained for an

	 arbitrary combination of these separate locking variants.



	 For more details, see Documentation/locking/lockdep-design.txt.



config LOCKDEP

	bool

	depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
@@ -1158,28 +1181,6 @@ config LOCKDEP 
config LOCKDEP_SMALL

	bool



config LOCK_STAT

	bool "Lock usage statistics"

	depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT

	select LOCKDEP

	select DEBUG_SPINLOCK

	select DEBUG_MUTEXES

	select DEBUG_RT_MUTEXES if RT_MUTEXES

	select DEBUG_LOCK_ALLOC

	default n

	help

	 This feature enables tracking lock contention points



	 For more details, see Documentation/locking/lockstat.txt



	 This also enables lock events required by "perf lock",

	 subcommand of perf.

	 If you want to use "perf lock", you also need to turn on

	 CONFIG_EVENT_TRACING.



	 CONFIG_LOCK_STAT defines "contended" and "acquired" lock events.

	 (CONFIG_LOCKDEP defines "acquire" and "release" events.)



config DEBUG_LOCKDEP

	bool "Lock dependency engine debugging"

	depends on DEBUG_KERNEL && LOCKDEP

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