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acpi: fix bogus preemption logic
The ACPI_PREEMPTION_POINT() logic was introduced in commit8bd108d
(ACPICA: add preemption point after each opcode parse). The follow up commitsabe1dfab6
,138d15692
,c084ca70
tried to fix the preemption logic back and forth, but nobody noticed that the usage of in_atomic_preempt_off() in that context is wrong. The check which guards the call of cond_resched() is: if (!in_atomic_preempt_off() && !irqs_disabled()) in_atomic_preempt_off() is not intended for general use as the comment above the macro definition clearly says: * Check whether we were atomic before we did preempt_disable(): * (used by the scheduler, *after* releasing the kernel lock) On a CONFIG_PREEMPT=n kernel the usage of in_atomic_preempt_off() works by accident, but with CONFIG_PREEMPT=y it's just broken. The whole purpose of the ACPI_PREEMPTION_POINT() is to reduce the latency on a CONFIG_PREEMPT=n kernel, so make ACPI_PREEMPTION_POINT() depend on CONFIG_PREEMPT=n and remove the in_atomic_preempt_off() check. Addresses https://bugzilla.kernel.org/show_bug.cgi?id=16210 [akpm@linux-foundation.org: fix build] Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: Len Brown <lenb@kernel.org> Cc: Francois Valenduc <francois.valenduc@tvcablenet.be> Cc: Lin Ming <ming.m.lin@intel.com> Cc: <stable@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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parent
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commit
0a7992c908
2 changed files with 8 additions and 3 deletions
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@ -33,6 +33,7 @@
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#include <linux/uaccess.h>
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#include <linux/cper.h>
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#include <linux/nmi.h>
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#include <linux/hardirq.h>
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#include <acpi/apei.h>
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#include "apei-internal.h"
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@ -148,13 +148,17 @@ static inline void *acpi_os_acquire_object(acpi_cache_t * cache)
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#define ACPI_ALLOCATE_ZEROED(a) acpi_os_allocate_zeroed(a)
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#define ACPI_FREE(a) kfree(a)
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/* Used within ACPICA to show where it is safe to preempt execution */
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#include <linux/hardirq.h>
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#ifndef CONFIG_PREEMPT
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/*
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* Used within ACPICA to show where it is safe to preempt execution
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* when CONFIG_PREEMPT=n
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*/
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#define ACPI_PREEMPTION_POINT() \
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do { \
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if (!in_atomic_preempt_off() && !irqs_disabled()) \
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if (!irqs_disabled()) \
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cond_resched(); \
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} while (0)
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#endif
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#endif /* __KERNEL__ */
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