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a14d39d7ac
Spinlocks aren't a good idea in userspace, where we can't actually disable preemption. Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>
44 lines
944 B
C
44 lines
944 B
C
#ifndef __LINUX_BIT_SPINLOCK_H
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#define __LINUX_BIT_SPINLOCK_H
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#include <linux/kernel.h>
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#include <linux/preempt.h>
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#include <linux/futex.h>
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static inline void bit_spin_lock(int nr, unsigned long *_addr)
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{
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u32 mask, *addr = ((u32 *) _addr) + (nr / 32), v;
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nr &= 31;
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mask = 1U << nr;
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while (1) {
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v = __atomic_fetch_or(addr, mask, __ATOMIC_ACQUIRE);
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if (!(v & mask))
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break;
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futex(addr, FUTEX_WAIT|FUTEX_PRIVATE_FLAG, v, NULL, NULL, 0);
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}
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}
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static inline void bit_spin_wake(int nr, unsigned long *_addr)
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{
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u32 *addr = ((u32 *) _addr) + (nr / 32);
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futex(addr, FUTEX_WAKE|FUTEX_PRIVATE_FLAG, INT_MAX, NULL, NULL, 0);
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}
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static inline void bit_spin_unlock(int nr, unsigned long *_addr)
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{
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u32 mask, *addr = ((u32 *) _addr) + (nr / 32);
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nr &= 31;
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mask = 1U << nr;
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__atomic_and_fetch(addr, ~mask, __ATOMIC_RELEASE);
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futex(addr, FUTEX_WAKE|FUTEX_PRIVATE_FLAG, INT_MAX, NULL, NULL, 0);
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}
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#endif /* __LINUX_BIT_SPINLOCK_H */
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