da5311258d
When a process changes CPUs while doing the non atomic cpu_local_* operations it might operate on the local_t of a different CPUs. Fix that by disabling preemption. Pointed out by Christopher Lameter Signed-off-by: Andi Kleen <ak@suse.de> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
89 lines
2.3 KiB
C
89 lines
2.3 KiB
C
#ifndef _ARCH_X8664_LOCAL_H
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#define _ARCH_X8664_LOCAL_H
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#include <linux/percpu.h>
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typedef struct
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{
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volatile long counter;
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} local_t;
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#define LOCAL_INIT(i) { (i) }
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#define local_read(v) ((v)->counter)
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#define local_set(v,i) (((v)->counter) = (i))
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static inline void local_inc(local_t *v)
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{
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__asm__ __volatile__(
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"incq %0"
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:"=m" (v->counter)
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:"m" (v->counter));
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}
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static inline void local_dec(local_t *v)
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{
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__asm__ __volatile__(
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"decq %0"
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:"=m" (v->counter)
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:"m" (v->counter));
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}
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static inline void local_add(long i, local_t *v)
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{
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__asm__ __volatile__(
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"addq %1,%0"
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:"=m" (v->counter)
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:"ir" (i), "m" (v->counter));
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}
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static inline void local_sub(long i, local_t *v)
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{
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__asm__ __volatile__(
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"subq %1,%0"
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:"=m" (v->counter)
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:"ir" (i), "m" (v->counter));
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}
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/* On x86-64 these are better than the atomic variants on SMP kernels
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because they dont use a lock prefix. */
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#define __local_inc(l) local_inc(l)
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#define __local_dec(l) local_dec(l)
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#define __local_add(i,l) local_add((i),(l))
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#define __local_sub(i,l) local_sub((i),(l))
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/* Use these for per-cpu local_t variables: on some archs they are
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* much more efficient than these naive implementations. Note they take
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* a variable, not an address.
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*
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* This could be done better if we moved the per cpu data directly
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* after GS.
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*/
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/* Need to disable preemption for the cpu local counters otherwise we could
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still access a variable of a previous CPU in a non atomic way. */
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#define cpu_local_wrap_v(v) \
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({ local_t res__; \
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preempt_disable(); \
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res__ = (v); \
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preempt_enable(); \
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res__; })
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#define cpu_local_wrap(v) \
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({ preempt_disable(); \
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v; \
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preempt_enable(); }) \
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#define cpu_local_read(v) cpu_local_wrap_v(local_read(&__get_cpu_var(v)))
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#define cpu_local_set(v, i) cpu_local_wrap(local_set(&__get_cpu_var(v), (i)))
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#define cpu_local_inc(v) cpu_local_wrap(local_inc(&__get_cpu_var(v)))
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#define cpu_local_dec(v) cpu_local_wrap(local_dec(&__get_cpu_var(v)))
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#define cpu_local_add(i, v) cpu_local_wrap(local_add((i), &__get_cpu_var(v)))
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#define cpu_local_sub(i, v) cpu_local_wrap(local_sub((i), &__get_cpu_var(v)))
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#define __cpu_local_inc(v) cpu_local_inc(v)
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#define __cpu_local_dec(v) cpu_local_dec(v)
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#define __cpu_local_add(i, v) cpu_local_add((i), (v))
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#define __cpu_local_sub(i, v) cpu_local_sub((i), (v))
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#endif /* _ARCH_I386_LOCAL_H */
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