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Diffstat (limited to 'arch/arc/include/asm/spinlock.h')
-rw-r--r--arch/arc/include/asm/spinlock.h299
1 files changed, 5 insertions, 294 deletions
diff --git a/arch/arc/include/asm/spinlock.h b/arch/arc/include/asm/spinlock.h
index 800e7c430ca5..233d5ffe6ec7 100644
--- a/arch/arc/include/asm/spinlock.h
+++ b/arch/arc/include/asm/spinlock.h
@@ -15,15 +15,13 @@
#define arch_spin_is_locked(x) ((x)->slock != __ARCH_SPIN_LOCK_UNLOCKED__)
#define arch_spin_lock_flags(lock, flags) arch_spin_lock(lock)
-#define arch_spin_unlock_wait(x) \
- do { while (arch_spin_is_locked(x)) cpu_relax(); } while (0)
-#ifdef CONFIG_ARC_HAS_LLSC
+static inline void arch_spin_unlock_wait(arch_spinlock_t *lock)
+{
+ smp_cond_load_acquire(&lock->slock, !VAL);
+}
-/*
- * A normal LLOCK/SCOND based system, w/o need for livelock workaround
- */
-#ifndef CONFIG_ARC_STAR_9000923308
+#ifdef CONFIG_ARC_HAS_LLSC
static inline void arch_spin_lock(arch_spinlock_t *lock)
{
@@ -238,293 +236,6 @@ 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)
generated by cgit v1.2.3 (git 2.39.0) at 2024-12-28 11:06:11 +0300