diff options
Diffstat (limited to 'arch/arc/include/asm/spinlock.h')
| -rw-r--r-- | arch/arc/include/asm/spinlock.h | 292 |
1 files changed, 0 insertions, 292 deletions
diff --git a/arch/arc/include/asm/spinlock.h b/arch/arc/include/asm/spinlock.h index 800e7c430ca5..cded4a9b5438 100644 --- a/arch/arc/include/asm/spinlock.h +++ b/arch/arc/include/asm/spinlock.h @@ -20,11 +20,6 @@ #ifdef CONFIG_ARC_HAS_LLSC -/* - * A normal LLOCK/SCOND based system, w/o need for livelock workaround - */ -#ifndef CONFIG_ARC_STAR_9000923308 - static inline void arch_spin_lock(arch_spinlock_t *lock) { unsigned int val; @@ -238,293 +233,6 @@ static inline void arch_write_unlock(arch_rwlock_t *rw) smp_mb(); } -#else /* CONFIG_ARC_STAR_9000923308 */ - -/* - * HS38x4 could get into a LLOCK/SCOND livelock in case of multiple overlapping - * coherency transactions in the SCU. The exclusive line state keeps rotating - * among contenting cores leading to a never ending cycle. So break the cycle - * by deferring the retry of failed exclusive access (SCOND). The actual delay - * needed is function of number of contending cores as well as the unrelated - * coherency traffic from other cores. To keep the code simple, start off with - * small delay of 1 which would suffice most cases and in case of contention - * double the delay. Eventually the delay is sufficient such that the coherency - * pipeline is drained, thus a subsequent exclusive access would succeed. - */ - -#define SCOND_FAIL_RETRY_VAR_DEF \ - unsigned int delay, tmp; \ - -#define SCOND_FAIL_RETRY_ASM \ - " ; --- scond fail delay --- \n" \ - " mov %[tmp], %[delay] \n" /* tmp = delay */ \ - "2: brne.d %[tmp], 0, 2b \n" /* while (tmp != 0) */ \ - " sub %[tmp], %[tmp], 1 \n" /* tmp-- */ \ - " rol %[delay], %[delay] \n" /* delay *= 2 */ \ - " b 1b \n" /* start over */ \ - " \n" \ - "4: ; --- done --- \n" \ - -#define SCOND_FAIL_RETRY_VARS \ - ,[delay] "=&r" (delay), [tmp] "=&r" (tmp) \ - -static inline void arch_spin_lock(arch_spinlock_t *lock) -{ - unsigned int val; - SCOND_FAIL_RETRY_VAR_DEF; - - smp_mb(); - - __asm__ __volatile__( - "0: mov %[delay], 1 \n" - "1: llock %[val], [%[slock]] \n" - " breq %[val], %[LOCKED], 0b \n" /* spin while LOCKED */ - " scond %[LOCKED], [%[slock]] \n" /* acquire */ - " bz 4f \n" /* done */ - " \n" - SCOND_FAIL_RETRY_ASM - - : [val] "=&r" (val) - SCOND_FAIL_RETRY_VARS - : [slock] "r" (&(lock->slock)), - [LOCKED] "r" (__ARCH_SPIN_LOCK_LOCKED__) - : "memory", "cc"); - - smp_mb(); -} - -/* 1 - lock taken successfully */ -static inline int arch_spin_trylock(arch_spinlock_t *lock) -{ - unsigned int val, got_it = 0; - SCOND_FAIL_RETRY_VAR_DEF; - - smp_mb(); - - __asm__ __volatile__( - "0: mov %[delay], 1 \n" - "1: llock %[val], [%[slock]] \n" - " breq %[val], %[LOCKED], 4f \n" /* already LOCKED, just bail */ - " scond %[LOCKED], [%[slock]] \n" /* acquire */ - " bz.d 4f \n" - " mov.z %[got_it], 1 \n" /* got it */ - " \n" - SCOND_FAIL_RETRY_ASM - - : [val] "=&r" (val), - [got_it] "+&r" (got_it) - SCOND_FAIL_RETRY_VARS - : [slock] "r" (&(lock->slock)), - [LOCKED] "r" (__ARCH_SPIN_LOCK_LOCKED__) - : "memory", "cc"); - - smp_mb(); - - return got_it; -} - -static inline void arch_spin_unlock(arch_spinlock_t *lock) -{ - smp_mb(); - - lock->slock = __ARCH_SPIN_LOCK_UNLOCKED__; - - smp_mb(); -} - -/* - * Read-write spinlocks, allowing multiple readers but only one writer. - * Unfair locking as Writers could be starved indefinitely by Reader(s) - */ - -static inline void arch_read_lock(arch_rwlock_t *rw) -{ - unsigned int val; - SCOND_FAIL_RETRY_VAR_DEF; - - smp_mb(); - - /* - * zero means writer holds the lock exclusively, deny Reader. - * Otherwise grant lock to first/subseq reader - * - * if (rw->counter > 0) { - * rw->counter--; - * ret = 1; - * } - */ - - __asm__ __volatile__( - "0: mov %[delay], 1 \n" - "1: llock %[val], [%[rwlock]] \n" - " brls %[val], %[WR_LOCKED], 0b\n" /* <= 0: spin while write locked */ - " sub %[val], %[val], 1 \n" /* reader lock */ - " scond %[val], [%[rwlock]] \n" - " bz 4f \n" /* done */ - " \n" - SCOND_FAIL_RETRY_ASM - - : [val] "=&r" (val) - SCOND_FAIL_RETRY_VARS - : [rwlock] "r" (&(rw->counter)), - [WR_LOCKED] "ir" (0) - : "memory", "cc"); - - smp_mb(); -} - -/* 1 - lock taken successfully */ -static inline int arch_read_trylock(arch_rwlock_t *rw) -{ - unsigned int val, got_it = 0; - SCOND_FAIL_RETRY_VAR_DEF; - - smp_mb(); - - __asm__ __volatile__( - "0: mov %[delay], 1 \n" - "1: llock %[val], [%[rwlock]] \n" - " brls %[val], %[WR_LOCKED], 4f\n" /* <= 0: already write locked, bail */ - " sub %[val], %[val], 1 \n" /* counter-- */ - " scond %[val], [%[rwlock]] \n" - " bz.d 4f \n" - " mov.z %[got_it], 1 \n" /* got it */ - " \n" - SCOND_FAIL_RETRY_ASM - - : [val] "=&r" (val), - [got_it] "+&r" (got_it) - SCOND_FAIL_RETRY_VARS - : [rwlock] "r" (&(rw->counter)), - [WR_LOCKED] "ir" (0) - : "memory", "cc"); - - smp_mb(); - - return got_it; -} - -static inline void arch_write_lock(arch_rwlock_t *rw) -{ - unsigned int val; - SCOND_FAIL_RETRY_VAR_DEF; - - smp_mb(); - - /* - * If reader(s) hold lock (lock < __ARCH_RW_LOCK_UNLOCKED__), - * deny writer. Otherwise if unlocked grant to writer - * Hence the claim that Linux rwlocks are unfair to writers. - * (can be starved for an indefinite time by readers). - * - * if (rw->counter == __ARCH_RW_LOCK_UNLOCKED__) { - * rw->counter = 0; - * ret = 1; - * } - */ - - __asm__ __volatile__( - "0: mov %[delay], 1 \n" - "1: llock %[val], [%[rwlock]] \n" - " brne %[val], %[UNLOCKED], 0b \n" /* while !UNLOCKED spin */ - " mov %[val], %[WR_LOCKED] \n" - " scond %[val], [%[rwlock]] \n" - " bz 4f \n" - " \n" - SCOND_FAIL_RETRY_ASM - - : [val] "=&r" (val) - SCOND_FAIL_RETRY_VARS - : [rwlock] "r" (&(rw->counter)), - [UNLOCKED] "ir" (__ARCH_RW_LOCK_UNLOCKED__), - [WR_LOCKED] "ir" (0) - : "memory", "cc"); - - smp_mb(); -} - -/* 1 - lock taken successfully */ -static inline int arch_write_trylock(arch_rwlock_t *rw) -{ - unsigned int val, got_it = 0; - SCOND_FAIL_RETRY_VAR_DEF; - - smp_mb(); - - __asm__ __volatile__( - "0: mov %[delay], 1 \n" - "1: llock %[val], [%[rwlock]] \n" - " brne %[val], %[UNLOCKED], 4f \n" /* !UNLOCKED, bail */ - " mov %[val], %[WR_LOCKED] \n" - " scond %[val], [%[rwlock]] \n" - " bz.d 4f \n" - " mov.z %[got_it], 1 \n" /* got it */ - " \n" - SCOND_FAIL_RETRY_ASM - - : [val] "=&r" (val), - [got_it] "+&r" (got_it) - SCOND_FAIL_RETRY_VARS - : [rwlock] "r" (&(rw->counter)), - [UNLOCKED] "ir" (__ARCH_RW_LOCK_UNLOCKED__), - [WR_LOCKED] "ir" (0) - : "memory", "cc"); - - smp_mb(); - - return got_it; -} - -static inline void arch_read_unlock(arch_rwlock_t *rw) -{ - unsigned int val; - - smp_mb(); - - /* - * rw->counter++; - */ - __asm__ __volatile__( - "1: llock %[val], [%[rwlock]] \n" - " add %[val], %[val], 1 \n" - " scond %[val], [%[rwlock]] \n" - " bnz 1b \n" - " \n" - : [val] "=&r" (val) - : [rwlock] "r" (&(rw->counter)) - : "memory", "cc"); - - smp_mb(); -} - -static inline void arch_write_unlock(arch_rwlock_t *rw) -{ - unsigned int val; - - smp_mb(); - - /* - * rw->counter = __ARCH_RW_LOCK_UNLOCKED__; - */ - __asm__ __volatile__( - "1: llock %[val], [%[rwlock]] \n" - " scond %[UNLOCKED], [%[rwlock]]\n" - " bnz 1b \n" - " \n" - : [val] "=&r" (val) - : [rwlock] "r" (&(rw->counter)), - [UNLOCKED] "r" (__ARCH_RW_LOCK_UNLOCKED__) - : "memory", "cc"); - - smp_mb(); -} - -#undef SCOND_FAIL_RETRY_VAR_DEF -#undef SCOND_FAIL_RETRY_ASM -#undef SCOND_FAIL_RETRY_VARS - -#endif /* CONFIG_ARC_STAR_9000923308 */ - #else /* !CONFIG_ARC_HAS_LLSC */ static inline void arch_spin_lock(arch_spinlock_t *lock) |
