mirror of
git://git.kernel.org/pub/scm/linux/kernel/git/xiang/erofs.git
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Michal Hocko
d47996082f
Introduce a generic implementation necessary for down_write_killable(). This is a trivial extension of the already existing down_write() call which can be interrupted by SIGKILL. This patch doesn't provide down_write_killable() yet because arches have to provide the necessary pieces before. rwsem_down_write_failed() which is a generic slow path for the write lock is extended to take a task state and renamed to __rwsem_down_write_failed_common(). The return value is either a valid semaphore pointer or ERR_PTR(-EINTR). rwsem_down_write_failed_killable() is exported as a new way to wait for the lock and be killable. For rwsem-spinlock implementation the current __down_write() it updated in a similar way as __rwsem_down_write_failed_common() except it doesn't need new exports just visible __down_write_killable(). Architectures which are not using the generic rwsem implementation are supposed to provide their __down_write_killable() implementation and use rwsem_down_write_failed_killable() for the slow path. Signed-off-by: Michal Hocko <[email protected]> Cc: Andrew Morton <[email protected]> Cc: Chris Zankel <[email protected]> Cc: David S. Miller <[email protected]> Cc: Linus Torvalds <[email protected]> Cc: Max Filippov <[email protected]> Cc: Paul E. McKenney <[email protected]> Cc: Peter Zijlstra <[email protected]> Cc: Signed-off-by: Davidlohr Bueso <[email protected]> Cc: Signed-off-by: Jason Low <[email protected]> Cc: Thomas Gleixner <[email protected]> Cc: Tony Luck <[email protected]> Cc: [email protected] Cc: [email protected] Cc: [email protected] Cc: [email protected] Cc: [email protected] Cc: [email protected] Cc: [email protected] Link: http://lkml.kernel.org/r/[email protected] Signed-off-by: Ingo Molnar <[email protected]>
46 lines
1.5 KiB
C
46 lines
1.5 KiB
C
/* rwsem-spinlock.h: fallback C implementation
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*
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* Copyright (c) 2001 David Howells ([email protected]).
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* - Derived partially from ideas by Andrea Arcangeli <[email protected]>
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* - Derived also from comments by Linus
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*/
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#ifndef _LINUX_RWSEM_SPINLOCK_H
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#define _LINUX_RWSEM_SPINLOCK_H
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#ifndef _LINUX_RWSEM_H
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#error "please don't include linux/rwsem-spinlock.h directly, use linux/rwsem.h instead"
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#endif
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#ifdef __KERNEL__
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/*
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* the rw-semaphore definition
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* - if count is 0 then there are no active readers or writers
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* - if count is +ve then that is the number of active readers
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* - if count is -1 then there is one active writer
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* - if wait_list is not empty, then there are processes waiting for the semaphore
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*/
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struct rw_semaphore {
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__s32 count;
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raw_spinlock_t wait_lock;
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struct list_head wait_list;
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#ifdef CONFIG_DEBUG_LOCK_ALLOC
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struct lockdep_map dep_map;
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#endif
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};
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#define RWSEM_UNLOCKED_VALUE 0x00000000
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extern void __down_read(struct rw_semaphore *sem);
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extern int __down_read_trylock(struct rw_semaphore *sem);
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extern void __down_write(struct rw_semaphore *sem);
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extern int __must_check __down_write_killable(struct rw_semaphore *sem);
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extern int __down_write_trylock(struct rw_semaphore *sem);
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extern void __up_read(struct rw_semaphore *sem);
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extern void __up_write(struct rw_semaphore *sem);
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extern void __downgrade_write(struct rw_semaphore *sem);
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extern int rwsem_is_locked(struct rw_semaphore *sem);
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#endif /* __KERNEL__ */
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#endif /* _LINUX_RWSEM_SPINLOCK_H */
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