cd689985cf
To allow the implementation of optimized rw-locks in user space, glibc needs a possibility to select waiters for wakeup depending on a bitset mask. This requires two new futex OPs: FUTEX_WAIT_BITS and FUTEX_WAKE_BITS These OPs are basically the same as FUTEX_WAIT and FUTEX_WAKE plus an additional argument - a bitset. Further the FUTEX_WAIT_BITS OP is expecting an absolute timeout value instead of the relative one, which is used for the FUTEX_WAIT OP. FUTEX_WAIT_BITS calls into the kernel with a bitset. The bitset is stored in the futex_q structure, which is used to enqueue the waiter into the hashed futex waitqueue. FUTEX_WAKE_BITS also calls into the kernel with a bitset. The wakeup function logically ANDs the bitset with the bitset stored in each waiters futex_q structure. If the result is zero (i.e. none of the set bits in the bitsets is matching), then the waiter is not woken up. If the result is not zero (i.e. one of the set bits in the bitsets is matching), then the waiter is woken. The bitset provided by the caller must be non zero. In case the provided bitset is zero the kernel returns EINVAL. Internaly the new OPs are only extensions to the existing FUTEX_WAIT and FUTEX_WAKE functions. The existing OPs hand a bitset with all bits set into the futex_wait() and futex_wake() functions. Signed-off-by: Thomas Gleixner <tgxl@linutronix.de> Signed-off-by: Ingo Molnar <mingo@elte.hu>
86 lines
2 KiB
C
86 lines
2 KiB
C
/* thread_info.h: common low-level thread information accessors
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*
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* Copyright (C) 2002 David Howells (dhowells@redhat.com)
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* - Incorporating suggestions made by Linus Torvalds
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*/
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#ifndef _LINUX_THREAD_INFO_H
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#define _LINUX_THREAD_INFO_H
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#include <linux/types.h>
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/*
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* System call restart block.
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*/
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struct restart_block {
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long (*fn)(struct restart_block *);
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union {
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struct {
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unsigned long arg0, arg1, arg2, arg3;
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};
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/* For futex_wait */
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struct {
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u32 *uaddr;
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u32 val;
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u32 flags;
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u32 bitset;
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u64 time;
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} futex;
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};
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};
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extern long do_no_restart_syscall(struct restart_block *parm);
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#include <linux/bitops.h>
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#include <asm/thread_info.h>
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#ifdef __KERNEL__
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/*
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* flag set/clear/test wrappers
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* - pass TIF_xxxx constants to these functions
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*/
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static inline void set_ti_thread_flag(struct thread_info *ti, int flag)
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{
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set_bit(flag, (unsigned long *)&ti->flags);
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}
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static inline void clear_ti_thread_flag(struct thread_info *ti, int flag)
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{
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clear_bit(flag, (unsigned long *)&ti->flags);
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}
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static inline int test_and_set_ti_thread_flag(struct thread_info *ti, int flag)
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{
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return test_and_set_bit(flag, (unsigned long *)&ti->flags);
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}
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static inline int test_and_clear_ti_thread_flag(struct thread_info *ti, int flag)
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{
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return test_and_clear_bit(flag, (unsigned long *)&ti->flags);
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}
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static inline int test_ti_thread_flag(struct thread_info *ti, int flag)
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{
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return test_bit(flag, (unsigned long *)&ti->flags);
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}
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#define set_thread_flag(flag) \
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set_ti_thread_flag(current_thread_info(), flag)
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#define clear_thread_flag(flag) \
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clear_ti_thread_flag(current_thread_info(), flag)
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#define test_and_set_thread_flag(flag) \
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test_and_set_ti_thread_flag(current_thread_info(), flag)
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#define test_and_clear_thread_flag(flag) \
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test_and_clear_ti_thread_flag(current_thread_info(), flag)
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#define test_thread_flag(flag) \
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test_ti_thread_flag(current_thread_info(), flag)
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#define set_need_resched() set_thread_flag(TIF_NEED_RESCHED)
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#define clear_need_resched() clear_thread_flag(TIF_NEED_RESCHED)
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#endif
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#endif /* _LINUX_THREAD_INFO_H */
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