lockdep: Add preemption enabled/disabled assertion APIs (8fd8ad5c) · Commits · 戴 / test

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: ("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

include/linux/lockdep.h

+19 −0

Original line number	Diff line number	Diff line
		@@ -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

lib/Kconfig.debug

+1 −0

Original line number	Diff line number	Diff line
		@@ -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
		help

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