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.
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| @@ -549,6 +549,22 @@ do { \ · 548 unmodified lines | |||
| 549 | WARN_ON_ONCE(debug_locks && !this_cpu_read(hardirq_context)); \ | 549 | WARN_ON_ONCE(debug_locks && !this_cpu_read(hardirq_context)); \ |
| 550 | } while (0) | 550 | } while (0) |
| 551 | 551 | ||
| 552 | #define lockdep_assert_preemption_enabled() \ | ||
| 553 | do { \ | ||
| 554 | WARN_ON_ONCE(IS_ENABLED(CONFIG_PREEMPT_COUNT) && \ | ||
| 555 | debug_locks && \ | ||
| 556 | (preempt_count() != 0 || \ | ||
| 557 | !this_cpu_read(hardirqs_enabled))); \ | ||
| 558 | } while (0) | ||
| 559 | |||
| 560 | #define lockdep_assert_preemption_disabled() \ | ||
| 561 | do { \ | ||
| 562 | WARN_ON_ONCE(IS_ENABLED(CONFIG_PREEMPT_COUNT) && \ | ||
| 563 | debug_locks && \ | ||
| 564 | (preempt_count() == 0 && \ | ||
| 565 | this_cpu_read(hardirqs_enabled))); \ | ||
| 566 | } while (0) | ||
| 567 | |||
| 552 | #else | 568 | #else |
| 553 | # define might_lock(lock) do { } while (0) | 569 | # define might_lock(lock) do { } while (0) |
| 554 | # define might_lock_read(lock) do { } while (0) | 570 | # define might_lock_read(lock) do { } while (0) |
| @@ -557,6 +573,9 @@ do { \ · 2 unmodified lines | |||
| 557 | # define lockdep_assert_irqs_enabled() do { } while (0) | 573 | # define lockdep_assert_irqs_enabled() do { } while (0) |
| 558 | # define lockdep_assert_irqs_disabled() do { } while (0) | 574 | # define lockdep_assert_irqs_disabled() do { } while (0) |
| 559 | # define lockdep_assert_in_irq() do { } while (0) | 575 | # define lockdep_assert_in_irq() do { } while (0) |
| 576 | |||
| 577 | # define lockdep_assert_preemption_enabled() do { } while (0) | ||
| 578 | # define lockdep_assert_preemption_disabled() do { } while (0) | ||
| 560 | #endif | 579 | #endif |
| 561 | 580 | ||
| 562 | #ifdef CONFIG_PROVE_RAW_LOCK_NESTING | 581 | #ifdef CONFIG_PROVE_RAW_LOCK_NESTING |