| From | "Ahmed S. Darwish" <> | Subject | [PATCH v3 04/20] lockdep: Add preemption enabled/disabled assertion APIs | Date | Tue, 30 Jun 2020 07:44:36 +0200 |
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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: f54bb2ec02c8 ("locking/lockdep: Add IRQs disabled/enabled assertion APIs: ...") Signed-off-by: Ahmed S. Darwish <a.darwish@linutronix.de> --- include/linux/lockdep.h | 18 ++++++++++++++++++ lib/Kconfig.debug | 1 + 2 files changed, 19 insertions(+)
diff --git a/include/linux/lockdep.h b/include/linux/lockdep.h index fd04b9e96091..53eff6b26fac 100644 --- a/include/linux/lockdep.h +++ b/include/linux/lockdep.h @@ -548,6 +548,22 @@ 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) @@ -556,6 +572,8 @@ 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 diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug index d74ac0fd6b2d..e5e2e632b749 100644 --- a/lib/Kconfig.debug +++ b/lib/Kconfig.debug @@ -1118,6 +1118,7 @@ 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 -- 2.20.1
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