/* * Generic implementation of 64-bit atomics using spinlocks, * useful on processors that don't have 64-bit atomic instructions. * * Copyright © 2009 Paul Mackerras, IBM Corp. * * This program is free software; you can redistribute it and/or * modify it under the terms of the GNU General Public License * as published by the Free Software Foundation; either version * 2 of the License, or (at your option) any later version. */ #include #include #include #include #include #include /* * We use a hashed array of spinlocks to provide exclusive access * to each atomic64_t variable. Since this is expected to used on * systems with small numbers of CPUs (<= 4 or so), we use a * relatively small array of 16 spinlocks to avoid wasting too much * memory on the spinlock array. */ #define NR_LOCKS 16 /* * Ensure each lock is in a separate cacheline. */ static union { raw_spinlock_t lock; char pad[L1_CACHE_BYTES]; } atomic64_lock[NR_LOCKS] __cacheline_aligned_in_smp = { [0 ... (NR_LOCKS - 1)] = { .lock = __RAW_SPIN_LOCK_UNLOCKED(atomic64_lock.lock), }, }; static inline raw_spinlock_t *lock_addr(const atomic64_t *v) { unsigned long addr = (unsigned long) v; addr >>= L1_CACHE_SHIFT; addr ^= (addr >> 8) ^ (addr >> 16); return &atomic64_lock[addr & (NR_LOCKS - 1)].lock; } long long atomic64_read(const atomic64_t *v) { unsigned long flags; raw_spinlock_t *lock = lock_addr(v); long long val; raw_spin_lock_irqsave(lock, flags); val = v->counter; raw_spin_unlock_irqrestore(lock, flags); return val; } EXPORT_SYMBOL(atomic64_read); void atomic64_set(atomic64_t *v, long long i) { unsigned long flags; raw_spinlock_t *lock = lock_addr(v); raw_spin_lock_irqsave(lock, flags); v->counter = i; raw_spin_unlock_irqrestore(lock, flags); } EXPORT_SYMBOL(atomic64_set); #define ATOMIC64_OP(op, c_op) \ void atomic64_##op(long long a, atomic64_t *v) \ { \ unsigned long flags; \ raw_spinlock_t *lock = lock_addr(v); \ \ raw_spin_lock_irqsave(lock, flags); \ v->counter c_op a; \ raw_spin_unlock_irqrestore(lock, flags); \ } \ EXPORT_SYMBOL(atomic64_##op); #define ATOMIC64_OP_RETURN(op, c_op) \ long long atomic64_##op##_return(long long a, atomic64_t *v) \ { \ unsigned long flags; \ raw_spinlock_t *lock = lock_addr(v); \ long long val; \ \ raw_spin_lock_irqsave(lock, flags); \ val = (v->counter c_op a); \ raw_spin_unlock_irqrestore(lock, flags); \ return val; \ } \ EXPORT_SYMBOL(atomic64_##op##_return); #define ATOMIC64_FETCH_OP(op, c_op) \ long long atomic64_fetch_##op(long long a, atomic64_t *v) \ { \ unsigned long flags; \ raw_spinlock_t *lock = lock_addr(v); \ long long val; \ \ raw_spin_lock_irqsave(lock, flags); \ val = v->counter; \ v->counter c_op a; \ raw_spin_unlock_irqrestore(lock, flags); \ return val; \ } \ EXPORT_SYMBOL(atomic64_fetch_##op); #define ATOMIC64_OPS(op, c_op) \ ATOMIC64_OP(op, c_op) \ ATOMIC64_OP_RETURN(op, c_op) \ ATOMIC64_FETCH_OP(op, c_op) ATOMIC64_OPS(add, +=) ATOMIC64_OPS(sub, -=) #undef ATOMIC64_OPS #define ATOMIC64_OPS(op, c_op) \ ATOMIC64_OP(op, c_op) \ ATOMIC64_OP_RETURN(op, c_op) \ ATOMIC64_FETCH_OP(op, c_op) ATOMIC64_OPS(and, &=) ATOMIC64_OPS(or, |=) ATOMIC64_OPS(xor, ^=) #undef ATOMIC64_OPS #undef ATOMIC64_FETCH_OP #undef ATOMIC64_OP_RETURN #undef ATOMIC64_OP long long atomic64_dec_if_positive(atomic64_t *v) { unsigned long flags; raw_spinlock_t *lock = lock_addr(v); long long val; raw_spin_lock_irqsave(lock, flags); val = v->counter - 1; if (val >= 0) v->counter = val; raw_spin_unlock_irqrestore(lock, flags); return val; } EXPORT_SYMBOL(atomic64_dec_if_positive); long long atomic64_cmpxchg(atomic64_t *v, long long o, long long n) { unsigned long flags; raw_spinlock_t *lock = lock_addr(v); long long val; raw_spin_lock_irqsave(lock, flags); val = v->counter; if (val == o) v->counter = n; raw_spin_unlock_irqrestore(lock, flags); return val; } EXPORT_SYMBOL(atomic64_cmpxchg); long long atomic64_xchg(atomic64_t *v, long long new) { unsigned long flags; raw_spinlock_t *lock = lock_addr(v); long long val; raw_spin_lock_irqsave(lock, flags); val = v->counter; v->counter = new; raw_spin_unlock_irqrestore(lock, flags); return val; } EXPORT_SYMBOL(atomic64_xchg); int atomic64_add_unless(atomic64_t *v, long long a, long long u) { unsigned long flags; raw_spinlock_t *lock = lock_addr(v); int ret = 0; raw_spin_lock_irqsave(lock, flags); if (v->counter != u) { v->counter += a; ret = 1; } raw_spin_unlock_irqrestore(lock, flags); return ret; } EXPORT_SYMBOL(atomic64_add_unless); edt@goodmis.org>2017-01-31 09:13:49 -0500 commit79c6f448c8b79c321e4a1f31f98194e4f6b6cae7 (patch) tree370efda701f03cccf21e02bb1fdd3b852547d75c /sound/drivers parent0c744ea4f77d72b3dcebb7a8f2684633ec79be88 (diff)
tracing: Fix hwlat kthread migration
The hwlat tracer creates a kernel thread at start of the tracer. It is pinned to a single CPU and will move to the next CPU after each period of running. If the user modifies the migration thread's affinity, it will not change after that happens. The original code created the thread at the first instance it was called, but later was changed to destroy the thread after the tracer was finished, and would not be created until the next instance of the tracer was established. The code that initialized the affinity was only called on the initial instantiation of the tracer. After that, it was not initialized, and the previous affinity did not match the current newly created one, making it appear that the user modified the thread's affinity when it did not, and the thread failed to migrate again. Cc: stable@vger.kernel.org Fixes: 0330f7aa8ee6 ("tracing: Have hwlat trace migrate across tracing_cpumask CPUs") Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Diffstat (limited to 'sound/drivers')