Release 4.7 arch/sh/include/asm/mutex-llsc.h
/*
* arch/sh/include/asm/mutex-llsc.h
*
* SH-4A optimized mutex locking primitives
*
* Please look into asm-generic/mutex-xchg.h for a formal definition.
*/
#ifndef __ASM_SH_MUTEX_LLSC_H
#define __ASM_SH_MUTEX_LLSC_H
/*
* Attempting to lock a mutex on SH4A is done like in ARMv6+ architecure.
* with a bastardized atomic decrement (it is not a reliable atomic decrement
* but it satisfies the defined semantics for our purpose, while being
* smaller and faster than a real atomic decrement or atomic swap.
* The idea is to attempt decrementing the lock value only once. If once
* decremented it isn't zero, or if its store-back fails due to a dispute
* on the exclusive store, we simply bail out immediately through the slow
* path where the lock will be reattempted until it succeeds.
*/
static inline void
__mutex_fastpath_lock(atomic_t *count, void (*fail_fn)(atomic_t *))
{
int __done, __res;
__asm__ __volatile__ (
"movli.l @%2, %0 \n"
"add #-1, %0 \n"
"movco.l %0, @%2 \n"
"movt %1 \n"
: "=&z" (__res), "=&r" (__done)
: "r" (&(count)->counter)
: "t");
if (unlikely(!__done || __res != 0))
fail_fn(count);
}
Contributors
| Person | Tokens | Prop | Commits | CommitProp |
| michael trimarchi | michael trimarchi | 40 | 86.96% | 1 | 33.33% |
| takashi yoshii | takashi yoshii | 5 | 10.87% | 1 | 33.33% |
| paul mundt | paul mundt | 1 | 2.17% | 1 | 33.33% |
| Total | 46 | 100.00% | 3 | 100.00% |
static inline int
__mutex_fastpath_lock_retval(atomic_t *count)
{
int __done, __res;
__asm__ __volatile__ (
"movli.l @%2, %0 \n"
"add #-1, %0 \n"
"movco.l %0, @%2 \n"
"movt %1 \n"
: "=&z" (__res), "=&r" (__done)
: "r" (&(count)->counter)
: "t");
if (unlikely(!__done || __res != 0))
__res = -1;
return __res;
}
Contributors
| Person | Tokens | Prop | Commits | CommitProp |
| michael trimarchi | michael trimarchi | 31 | 79.49% | 1 | 25.00% |
| takashi yoshii | takashi yoshii | 5 | 12.82% | 1 | 25.00% |
| maarten lankhorst | maarten lankhorst | 2 | 5.13% | 1 | 25.00% |
| paul mundt | paul mundt | 1 | 2.56% | 1 | 25.00% |
| Total | 39 | 100.00% | 4 | 100.00% |
static inline void
__mutex_fastpath_unlock(atomic_t *count, void (*fail_fn)(atomic_t *))
{
int __done, __res;
__asm__ __volatile__ (
"movli.l @%2, %0 \n\t"
"add #1, %0 \n\t"
"movco.l %0, @%2 \n\t"
"movt %1 \n\t"
: "=&z" (__res), "=&r" (__done)
: "r" (&(count)->counter)
: "t");
if (unlikely(!__done || __res <= 0))
fail_fn(count);
}
Contributors
| Person | Tokens | Prop | Commits | CommitProp |
| michael trimarchi | michael trimarchi | 39 | 84.78% | 1 | 25.00% |
| takashi yoshii | takashi yoshii | 5 | 10.87% | 1 | 25.00% |
| paul mundt | paul mundt | 2 | 4.35% | 2 | 50.00% |
| Total | 46 | 100.00% | 4 | 100.00% |
/*
* If the unlock was done on a contended lock, or if the unlock simply fails
* then the mutex remains locked.
*/
#define __mutex_slowpath_needs_to_unlock() 1
/*
* For __mutex_fastpath_trylock we do an atomic decrement and check the
* result and put it in the __res variable.
*/
static inline int
__mutex_fastpath_trylock(atomic_t *count, int (*fail_fn)(atomic_t *))
{
int __res, __orig;
__asm__ __volatile__ (
"1: movli.l @%2, %0 \n\t"
"dt %0 \n\t"
"movco.l %0,@%2 \n\t"
"bf 1b \n\t"
"cmp/eq #0,%0 \n\t"
"bt 2f \n\t"
"mov #0, %1 \n\t"
"bf 3f \n\t"
"2: mov #1, %1 \n\t"
"3: "
: "=&z" (__orig), "=&r" (__res)
: "r" (&count->counter)
: "t");
return __res;
}
Contributors
| Person | Tokens | Prop | Commits | CommitProp |
| michael trimarchi | michael trimarchi | 32 | 100.00% | 1 | 100.00% |
| Total | 32 | 100.00% | 1 | 100.00% |
#endif /* __ASM_SH_MUTEX_LLSC_H */
Overall Contributors
| Person | Tokens | Prop | Commits | CommitProp |
| michael trimarchi | michael trimarchi | 160 | 88.40% | 1 | 20.00% |
| takashi yoshii | takashi yoshii | 15 | 8.29% | 1 | 20.00% |
| paul mundt | paul mundt | 4 | 2.21% | 2 | 40.00% |
| maarten lankhorst | maarten lankhorst | 2 | 1.10% | 1 | 20.00% |
| Total | 181 | 100.00% | 5 | 100.00% |
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