/* * Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com) * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License version 2 as * published by the Free Software Foundation. */ #ifndef __ASM_SPINLOCK_H #define __ASM_SPINLOCK_H #include <asm/spinlock_types.h> #include <asm/processor.h> #include <asm/barrier.h> #define arch_spin_is_locked(x) ((x)->slock != __ARCH_SPIN_LOCK_UNLOCKED__) #ifdef CONFIG_ARC_HAS_LLSC static inline void arch_spin_lock(arch_spinlock_t *lock) { unsigned int val; smp_mb(); __asm__ __volatile__( "1: llock %[val], [%[slock]] \n" " breq %[val], %[LOCKED], 1b \n" /* spin while LOCKED */ " scond %[LOCKED], [%[slock]] \n" /* acquire */ " bnz 1b \n" " \n" : [val] "=&r" (val) : [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; smp_mb(); __asm__ __volatile__( "1: llock %[val], [%[slock]] \n" " breq %[val], %[LOCKED], 4f \n" /* already LOCKED, just bail */ " scond %[LOCKED], [%[slock]] \n" /* acquire */ " bnz 1b \n" " mov %[got_it], 1 \n" "4: \n" " \n" : [val] "=&r" (val), [got_it] "+&r" (got_it) : [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; 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__( "1: llock %[val], [%[rwlock]] \n" " brls %[val], %[WR_LOCKED], 1b\n" /* <= 0: spin while write locked */ " sub %[val], %[val], 1 \n" /* reader lock */ " scond %[val], [%[rwlock]] \n" " bnz 1b \n" " \n" : [val] "=&r" (val) : [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; smp_mb(); __asm__ __volatile__( "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" " bnz 1b \n" /* retry if collided with someone */ " mov %[got_it], 1 \n" " \n" "4: ; --- done --- \n" : [val] "=&r" (val), [got_it] "+&r" (got_it) : [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; 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__( "1: llock %[val], [%[rwlock]] \n" " brne %[val], %[UNLOCKED], 1b \n" /* while !UNLOCKED spin */ " mov %[val], %[WR_LOCKED] \n" " scond %[val], [%[rwlock]] \n" " bnz 1b \n" " \n" : [val] "=&r" (val) : [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; smp_mb(); __asm__ __volatile__( "1: llock %[val], [%[rwlock]] \n" " brne %[val], %[UNLOCKED], 4f \n" /* !UNLOCKED, bail */ " mov %[val], %[WR_LOCKED] \n" " scond %[val], [%[rwlock]] \n" " bnz 1b \n" /* retry if collided with someone */ " mov %[got_it], 1 \n" " \n" "4: ; --- done --- \n" : [val] "=&r" (val), [got_it] "+&r" (got_it) : [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) { smp_mb(); rw->counter = __ARCH_RW_LOCK_UNLOCKED__; smp_mb(); } #else /* !CONFIG_ARC_HAS_LLSC */ static inline void arch_spin_lock(arch_spinlock_t *lock) { unsigned int val = __ARCH_SPIN_LOCK_LOCKED__; /* * This smp_mb() is technically superfluous, we only need the one * after the lock for providing the ACQUIRE semantics. * However doing the "right" thing was regressing hackbench * so keeping this, pending further investigation */ smp_mb(); __asm__ __volatile__( "1: ex %0, [%1] \n" #ifdef CONFIG_EZNPS_MTM_EXT " .word %3 \n" #endif " breq %0, %2, 1b \n" : "+&r" (val) : "r"(&(lock->slock)), "ir"(__ARCH_SPIN_LOCK_LOCKED__) #ifdef CONFIG_EZNPS_MTM_EXT , "i"(CTOP_INST_SCHD_RW) #endif : "memory"); /* * ACQUIRE barrier to ensure load/store after taking the lock * don't "bleed-up" out of the critical section (leak-in is allowed) * http://www.spinics.net/lists/kernel/msg2010409.html * * ARCv2 only has load-load, store-store and all-all barrier * thus need the full all-all barrier */ smp_mb(); } /* 1 - lock taken successfully */ static inline int arch_spin_trylock(arch_spinlock_t *lock) { unsigned int val = __ARCH_SPIN_LOCK_LOCKED__; smp_mb(); __asm__ __volatile__( "1: ex %0, [%1] \n" : "+r" (val) : "r"(&(lock->slock)) : "memory"); smp_mb(); return (val == __ARCH_SPIN_LOCK_UNLOCKED__); } static inline void arch_spin_unlock(arch_spinlock_t *lock) { unsigned int val = __ARCH_SPIN_LOCK_UNLOCKED__; /* * RELEASE barrier: given the instructions avail on ARCv2, full barrier * is the only option */ smp_mb(); /* * EX is not really required here, a simple STore of 0 suffices. * However this causes tasklist livelocks in SystemC based SMP virtual * platforms where the systemc core scheduler uses EX as a cue for * moving to next core. Do a git log of this file for details */ __asm__ __volatile__( " ex %0, [%1] \n" : "+r" (val) : "r"(&(lock->slock)) : "memory"); /* * superfluous, but keeping for now - see pairing version in * arch_spin_lock above */ smp_mb(); } /* * Read-write spinlocks, allowing multiple readers but only one writer. * Unfair locking as Writers could be starved indefinitely by Reader(s) * * The spinlock itself is contained in @counter and access to it is * serialized with @lock_mutex. */ /* 1 - lock taken successfully */ static inline int arch_read_trylock(arch_rwlock_t *rw) { int ret = 0; unsigned long flags; local_irq_save(flags); arch_spin_lock(&(rw->lock_mutex)); /* * zero means writer holds the lock exclusively, deny Reader. * Otherwise grant lock to first/subseq reader */ if (rw->counter > 0) { rw->counter--; ret = 1; } arch_spin_unlock(&(rw->lock_mutex)); local_irq_restore(flags); smp_mb(); return ret; } /* 1 - lock taken successfully */ static inline int arch_write_trylock(arch_rwlock_t *rw) { int ret = 0; unsigned long flags; local_irq_save(flags); arch_spin_lock(&(rw->lock_mutex)); /* * 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; } arch_spin_unlock(&(rw->lock_mutex)); local_irq_restore(flags); return ret; } static inline void arch_read_lock(arch_rwlock_t *rw) { while (!arch_read_trylock(rw)) cpu_relax(); } static inline void arch_write_lock(arch_rwlock_t *rw) { while (!arch_write_trylock(rw)) cpu_relax(); } static inline void arch_read_unlock(arch_rwlock_t *rw) { unsigned long flags; local_irq_save(flags); arch_spin_lock(&(rw->lock_mutex)); rw->counter++; arch_spin_unlock(&(rw->lock_mutex)); local_irq_restore(flags); } static inline void arch_write_unlock(arch_rwlock_t *rw) { unsigned long flags; local_irq_save(flags); arch_spin_lock(&(rw->lock_mutex)); rw->counter = __ARCH_RW_LOCK_UNLOCKED__; arch_spin_unlock(&(rw->lock_mutex)); local_irq_restore(flags); } #endif #endif /* __ASM_SPINLOCK_H */
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arcregs.h | File | 8.59 KB | 0644 |
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asm-offsets.h | File | 311 B | 0644 |
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atomic.h | File | 15.14 KB | 0644 |
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barrier.h | File | 1.75 KB | 0644 |
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bitops.h | File | 9.81 KB | 0644 |
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bug.h | File | 938 B | 0644 |
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cache.h | File | 3.77 KB | 0644 |
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cacheflush.h | File | 3.88 KB | 0644 |
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checksum.h | File | 2.45 KB | 0644 |
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cmpxchg.h | File | 5.4 KB | 0644 |
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current.h | File | 695 B | 0644 |
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delay.h | File | 1.99 KB | 0644 |
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disasm.h | File | 3.87 KB | 0644 |
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dma-mapping.h | File | 734 B | 0644 |
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dma.h | File | 459 B | 0644 |
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dwarf.h | File | 892 B | 0644 |
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elf.h | File | 2.15 KB | 0644 |
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entry-arcv2.h | File | 4.85 KB | 0644 |
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entry-compact.h | File | 9.29 KB | 0644 |
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entry.h | File | 6.73 KB | 0644 |
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exec.h | File | 410 B | 0644 |
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fb.h | File | 411 B | 0644 |
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futex.h | File | 3.67 KB | 0644 |
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highmem.h | File | 1.46 KB | 0644 |
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hugepage.h | File | 2.41 KB | 0644 |
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io.h | File | 6.43 KB | 0644 |
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irq.h | File | 825 B | 0644 |
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irqflags-arcv2.h | File | 3.45 KB | 0644 |
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irqflags-compact.h | File | 4.25 KB | 0644 |
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irqflags.h | File | 509 B | 0644 |
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kdebug.h | File | 400 B | 0644 |
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kgdb.h | File | 1.35 KB | 0644 |
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kmap_types.h | File | 489 B | 0644 |
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kprobes.h | File | 1.37 KB | 0644 |
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linkage.h | File | 1.42 KB | 0644 |
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mach_desc.h | File | 2.06 KB | 0644 |
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mmu.h | File | 2.44 KB | 0644 |
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mmu_context.h | File | 5.67 KB | 0644 |
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mmzone.h | File | 989 B | 0644 |
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module.h | File | 661 B | 0644 |
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page.h | File | 2.99 KB | 0644 |
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pci.h | File | 705 B | 0644 |
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perf_event.h | File | 6.86 KB | 0644 |
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pgalloc.h | File | 3.79 KB | 0644 |
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pgtable.h | File | 14.2 KB | 0644 |
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processor.h | File | 4.69 KB | 0644 |
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ptrace.h | File | 3.87 KB | 0644 |
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sections.h | File | 407 B | 0644 |
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segment.h | File | 612 B | 0644 |
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serial.h | File | 644 B | 0644 |
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setup.h | File | 1.18 KB | 0644 |
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shmparam.h | File | 442 B | 0644 |
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smp.h | File | 4.25 KB | 0644 |
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spinlock.h | File | 8.79 KB | 0644 |
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spinlock_types.h | File | 1.03 KB | 0644 |
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stacktrace.h | File | 1.29 KB | 0644 |
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string.h | File | 1.15 KB | 0644 |
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switch_to.h | File | 1.17 KB | 0644 |
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syscall.h | File | 1.57 KB | 0644 |
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syscalls.h | File | 653 B | 0644 |
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thread_info.h | File | 3.39 KB | 0644 |
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timex.h | File | 508 B | 0644 |
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tlb-mmu1.h | File | 3.48 KB | 0644 |
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tlb.h | File | 1.23 KB | 0644 |
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tlbflush.h | File | 1.76 KB | 0644 |
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uaccess.h | File | 18.45 KB | 0644 |
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unaligned.h | File | 771 B | 0644 |
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unwind.h | File | 3.51 KB | 0644 |
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