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b5fd066153
We just wanted c sourcefiles out of the top level, not c source directories. Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
85 lines
2.1 KiB
C
85 lines
2.1 KiB
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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#include <urcu/futex.h>
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/*
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* The futex wait op wants an explicit 32-bit address and value. If the bitmap
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* used for the spinlock is 64-bit, cast down and pass the right 32-bit region
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* for the in-kernel checks. The value is the copy that has already been read
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* from the atomic op.
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*
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* The futex wake op interprets the value as the number of waiters to wake (up
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* to INT_MAX), so pass that along directly.
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*/
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static inline void do_futex(int nr, unsigned long *addr, unsigned long v, int futex_flags)
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{
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u32 *addr32 = (u32 *) addr;
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u32 *v32 = (u32 *) &v;
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int shift = 0;
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futex_flags |= FUTEX_PRIVATE_FLAG;
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#if BITS_PER_LONG == 64
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#if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
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shift = (nr >= 32) ? 1 : 0;
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#else
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shift = (nr < 32) ? 1 : 0;
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#endif
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#endif
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if (shift) {
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addr32 += shift;
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v32 += shift;
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}
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/*
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* The shift to determine the futex address may have cast away a
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* literal wake count value. The value is capped to INT_MAX and thus
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* always in the low bytes of v regardless of bit nr. Copy in the wake
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* count to whatever 32-bit range was selected.
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*/
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if (futex_flags == FUTEX_WAKE_PRIVATE)
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*v32 = (u32) v;
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futex(addr32, futex_flags, *v32, NULL, NULL, 0);
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}
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static inline void bit_spin_lock(int nr, unsigned long *_addr)
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{
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unsigned long mask;
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unsigned long *addr = _addr + (nr / BITS_PER_LONG);
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unsigned long v;
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nr &= BITS_PER_LONG - 1;
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mask = 1UL << 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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do_futex(nr, addr, v, FUTEX_WAIT);
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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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do_futex(nr, _addr, INT_MAX, FUTEX_WAKE);
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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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unsigned long mask;
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unsigned long *addr = _addr + (nr / BITS_PER_LONG);
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nr &= BITS_PER_LONG - 1;
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mask = 1UL << nr;
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__atomic_and_fetch(addr, ~mask, __ATOMIC_RELEASE);
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do_futex(nr, addr, INT_MAX, FUTEX_WAKE);
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}
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#endif /* __LINUX_BIT_SPINLOCK_H */
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