cregit-Linux how code gets into the kernel

Release 4.7 arch/alpha/include/asm/rwsem.h

#ifndef _ALPHA_RWSEM_H

#define _ALPHA_RWSEM_H

/*
 * Written by Ivan Kokshaysky <ink@jurassic.park.msu.ru>, 2001.
 * Based on asm-alpha/semaphore.h and asm-i386/rwsem.h
 */

#ifndef _LINUX_RWSEM_H
#error "please don't include asm/rwsem.h directly, use linux/rwsem.h instead"
#endif

#ifdef __KERNEL__

#include <linux/compiler.h>


#define RWSEM_UNLOCKED_VALUE		0x0000000000000000L

#define RWSEM_ACTIVE_BIAS		0x0000000000000001L

#define RWSEM_ACTIVE_MASK		0x00000000ffffffffL

#define RWSEM_WAITING_BIAS		(-0x0000000100000000L)

#define RWSEM_ACTIVE_READ_BIAS		RWSEM_ACTIVE_BIAS

#define RWSEM_ACTIVE_WRITE_BIAS		(RWSEM_WAITING_BIAS + RWSEM_ACTIVE_BIAS)


static inline void __down_read(struct rw_semaphore *sem) { long oldcount; #ifndef CONFIG_SMP oldcount = sem->count; sem->count += RWSEM_ACTIVE_READ_BIAS; #else long temp; __asm__ __volatile__( "1: ldq_l %0,%1\n" " addq %0,%3,%2\n" " stq_c %2,%1\n" " beq %2,2f\n" " mb\n" ".subsection 2\n" "2: br 1b\n" ".previous" :"=&r" (oldcount), "=m" (sem->count), "=&r" (temp) :"Ir" (RWSEM_ACTIVE_READ_BIAS), "m" (sem->count) : "memory"); #endif if (unlikely(oldcount < 0)) rwsem_down_read_failed(sem); }

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linus torvaldslinus torvalds5398.15%150.00%
ivan kokshayskyivan kokshaysky11.85%150.00%
Total54100.00%2100.00%

/* * trylock for reading -- returns 1 if successful, 0 if contention */
static inline int __down_read_trylock(struct rw_semaphore *sem) { long old, new, res; res = sem->count; do { new = res + RWSEM_ACTIVE_READ_BIAS; if (new <= 0) break; old = res; res = cmpxchg(&sem->count, old, new); } while (res != old); return res >= 0 ? 1 : 0; }

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ivan kokshayskyivan kokshaysky75100.00%2100.00%
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static inline long ___down_write(struct rw_semaphore *sem) { long oldcount; #ifndef CONFIG_SMP oldcount = sem->count; sem->count += RWSEM_ACTIVE_WRITE_BIAS; #else long temp; __asm__ __volatile__( "1: ldq_l %0,%1\n" " addq %0,%3,%2\n" " stq_c %2,%1\n" " beq %2,2f\n" " mb\n" ".subsection 2\n" "2: br 1b\n" ".previous" :"=&r" (oldcount), "=m" (sem->count), "=&r" (temp) :"Ir" (RWSEM_ACTIVE_WRITE_BIAS), "m" (sem->count) : "memory"); #endif return oldcount; }

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linus torvaldslinus torvalds3786.05%150.00%
michal hockomichal hocko613.95%150.00%
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static inline void __down_write(struct rw_semaphore *sem) { if (unlikely(___down_write(sem))) rwsem_down_write_failed(sem); }

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michal hockomichal hocko1555.56%133.33%
linus torvaldslinus torvalds1140.74%133.33%
ivan kokshayskyivan kokshaysky13.70%133.33%
Total27100.00%3100.00%


static inline int __down_write_killable(struct rw_semaphore *sem) { if (unlikely(___down_write(sem))) if (IS_ERR(rwsem_down_write_failed_killable(sem))) return -EINTR; return 0; }

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michal hockomichal hocko39100.00%1100.00%
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/* * trylock for writing -- returns 1 if successful, 0 if contention */
static inline int __down_write_trylock(struct rw_semaphore *sem) { long ret = cmpxchg(&sem->count, RWSEM_UNLOCKED_VALUE, RWSEM_ACTIVE_WRITE_BIAS); if (ret == RWSEM_UNLOCKED_VALUE) return 1; return 0; }

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ivan kokshayskyivan kokshaysky39100.00%1100.00%
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static inline void __up_read(struct rw_semaphore *sem) { long oldcount; #ifndef CONFIG_SMP oldcount = sem->count; sem->count -= RWSEM_ACTIVE_READ_BIAS; #else long temp; __asm__ __volatile__( " mb\n" "1: ldq_l %0,%1\n" " subq %0,%3,%2\n" " stq_c %2,%1\n" " beq %2,2f\n" ".subsection 2\n" "2: br 1b\n" ".previous" :"=&r" (oldcount), "=m" (sem->count), "=&r" (temp) :"Ir" (RWSEM_ACTIVE_READ_BIAS), "m" (sem->count) : "memory"); #endif if (unlikely(oldcount < 0)) if ((int)oldcount - RWSEM_ACTIVE_READ_BIAS == 0) rwsem_wake(sem); }

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linus torvaldslinus torvalds6498.46%150.00%
ivan kokshayskyivan kokshaysky11.54%150.00%
Total65100.00%2100.00%


static inline void __up_write(struct rw_semaphore *sem) { long count; #ifndef CONFIG_SMP sem->count -= RWSEM_ACTIVE_WRITE_BIAS; count = sem->count; #else long temp; __asm__ __volatile__( " mb\n" "1: ldq_l %0,%1\n" " subq %0,%3,%2\n" " stq_c %2,%1\n" " beq %2,2f\n" " subq %0,%3,%0\n" ".subsection 2\n" "2: br 1b\n" ".previous" :"=&r" (count), "=m" (sem->count), "=&r" (temp) :"Ir" (RWSEM_ACTIVE_WRITE_BIAS), "m" (sem->count) : "memory"); #endif if (unlikely(count)) if ((int)count == 0) rwsem_wake(sem); }

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linus torvaldslinus torvalds6098.36%150.00%
ivan kokshayskyivan kokshaysky11.64%150.00%
Total61100.00%2100.00%

/* * downgrade write lock to read lock */
static inline void __downgrade_write(struct rw_semaphore *sem) { long oldcount; #ifndef CONFIG_SMP oldcount = sem->count; sem->count -= RWSEM_WAITING_BIAS; #else long temp; __asm__ __volatile__( "1: ldq_l %0,%1\n" " addq %0,%3,%2\n" " stq_c %2,%1\n" " beq %2,2f\n" " mb\n" ".subsection 2\n" "2: br 1b\n" ".previous" :"=&r" (oldcount), "=m" (sem->count), "=&r" (temp) :"Ir" (-RWSEM_WAITING_BIAS), "m" (sem->count) : "memory"); #endif if (unlikely(oldcount < 0)) rwsem_downgrade_wake(sem); }

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ivan kokshayskyivan kokshaysky54100.00%1100.00%
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static inline void rwsem_atomic_add(long val, struct rw_semaphore *sem) { #ifndef CONFIG_SMP sem->count += val; #else long temp; __asm__ __volatile__( "1: ldq_l %0,%1\n" " addq %0,%2,%0\n" " stq_c %0,%1\n" " beq %0,2f\n" ".subsection 2\n" "2: br 1b\n" ".previous" :"=&r" (temp), "=m" (sem->count) :"Ir" (val), "m" (sem->count)); #endif }

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linus torvaldslinus torvalds34100.00%1100.00%
Total34100.00%1100.00%


static inline long rwsem_atomic_update(long val, struct rw_semaphore *sem) { #ifndef CONFIG_SMP sem->count += val; return sem->count; #else long ret, temp; __asm__ __volatile__( "1: ldq_l %0,%1\n" " addq %0,%3,%2\n" " addq %0,%3,%0\n" " stq_c %2,%1\n" " beq %2,2f\n" ".subsection 2\n" "2: br 1b\n" ".previous" :"=&r" (ret), "=m" (sem->count), "=&r" (temp) :"Ir" (val), "m" (sem->count)); return ret; #endif }

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#endif /* __KERNEL__ */ #endif /* _ALPHA_RWSEM_H */

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linus torvaldslinus torvalds35359.93%233.33%
ivan kokshayskyivan kokshaysky17529.71%233.33%
michal hockomichal hocko6010.19%116.67%
michael hayesmichael hayes10.17%116.67%
Total589100.00%6100.00%
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