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lockdep: Add preemption enabled/disabled assertion APIs

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Asserting that preemption is enabled or disabled is a critical sanity
check.  Developers are usually reluctant to add such a check in a
fastpath as reading the preemption count can be costly.

Extend the lockdep API with macros asserting that preemption is disabled
or enabled. If lockdep is disabled, or if the underlying architecture
does not support kernel preemption, this assert has no runtime overhead.

References: f54bb2ec02 ("locking/lockdep: Add IRQs disabled/enabled assertion APIs: ...")
Signed-off-by: Ahmed S. Darwish <a.darwish@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20200720155530.1173732-8-a.darwish@linutronix.de
This commit is contained in:
Ahmed S. Darwish 2020-07-20 17:55:13 +02:00 committed by Peter Zijlstra
parent 932e463652
commit 8fd8ad5c5d
2 changed files with 20 additions and 0 deletions
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19
include/linux/lockdep.h
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@ -549,6 +549,22 @@ do { \
WARN_ON_ONCE(debug_locks && !this_cpu_read(hardirq_context)); \
} while (0)
#define lockdep_assert_preemption_enabled() \
do { \
WARN_ON_ONCE(IS_ENABLED(CONFIG_PREEMPT_COUNT) && \
debug_locks && \
(preempt_count() != 0 || \
!this_cpu_read(hardirqs_enabled))); \
} while (0)
#define lockdep_assert_preemption_disabled() \
do { \
WARN_ON_ONCE(IS_ENABLED(CONFIG_PREEMPT_COUNT) && \
debug_locks && \
(preempt_count() == 0 && \
this_cpu_read(hardirqs_enabled))); \
} while (0)
#else
# define might_lock(lock) do { } while (0)
# define might_lock_read(lock) do { } while (0)
@ -557,6 +573,9 @@ do { \
# define lockdep_assert_irqs_enabled() do { } while (0)
# define lockdep_assert_irqs_disabled() do { } while (0)
# define lockdep_assert_in_irq() do { } while (0)
# define lockdep_assert_preemption_enabled() do { } while (0)
# define lockdep_assert_preemption_disabled() do { } while (0)
#endif
#ifdef CONFIG_PROVE_RAW_LOCK_NESTING

1
lib/Kconfig.debug
View File

@ -1117,6 +1117,7 @@ config PROVE_LOCKING
select DEBUG_RWSEMS
select DEBUG_WW_MUTEX_SLOWPATH
select DEBUG_LOCK_ALLOC
select PREEMPT_COUNT if !ARCH_NO_PREEMPT
select TRACE_IRQFLAGS
default n
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