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Message-Id: <1522445280-7767-4-git-send-email-longman@redhat.com>
Date: Fri, 30 Mar 2018 17:28:00 -0400
From: Waiman Long <longman@...hat.com>
To: Ingo Molnar <mingo@...hat.com>,
Peter Zijlstra <peterz@...radead.org>,
Thomas Gleixner <tglx@...utronix.de>
Cc: linux-kernel@...r.kernel.org, Davidlohr Bueso <dave@...olabs.net>,
Waiman Long <longman@...hat.com>
Subject: [PATCH v5 3/3] lib/Kconfig.debug: 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: Waiman Long <longman@...hat.com>
Acked-by: Davidlohr Bueso <dave@...olabs.net>
---
lib/Kconfig.debug | 135 +++++++++++++++++++++++++++---------------------------
1 file changed, 68 insertions(+), 67 deletions(-)
diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index 0db85f5..dc9ffe2 100644
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -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
--
1.8.3.1
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