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https://github.com/openvswitch/ovs
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5878b92522
The atomic exchange operation is a useful primitive that should be available as well. Most compilers already expose or offer a way to use it, but a single symbol needs to be defined. Signed-off-by: Gaetan Rivet <grive@u256.net> Reviewed-by: Eli Britstein <elibr@nvidia.com> Reviewed-by: Maxime Coquelin <maxime.coquelin@redhat.com> Signed-off-by: Ilya Maximets <i.maximets@ovn.org>
53 lines
1.9 KiB
C
53 lines
1.9 KiB
C
/* This header implements atomic operation locking helpers. */
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#ifndef IN_OVS_ATOMIC_H
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#error "This header should only be included indirectly via ovs-atomic.h."
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#endif
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#define OVS_ATOMIC_LOCKED_IMPL 1
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void atomic_lock__(void *);
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void atomic_unlock__(void *);
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#define atomic_store_locked(DST, SRC) \
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(atomic_lock__(DST), \
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*(DST) = (SRC), \
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atomic_unlock__(DST), \
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(void) 0)
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#define atomic_read_locked(SRC, DST) \
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(atomic_lock__(SRC), \
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*(DST) = *(SRC), \
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atomic_unlock__(SRC), \
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(void) 0)
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/* XXX: Evaluates EXP multiple times. */
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#define atomic_compare_exchange_locked(DST, EXP, SRC) \
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(atomic_lock__(DST), \
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(*(DST) == *(EXP) \
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? (*(DST) = (SRC), \
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atomic_unlock__(DST), \
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true) \
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: (*(EXP) = *(DST), \
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atomic_unlock__(DST), \
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false)))
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#define atomic_exchange_locked(DST, SRC) \
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({ \
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atomic_lock__(DST); \
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typeof(*(DST)) __tmp = *(DST); \
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*(DST) = SRC; \
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atomic_unlock__(DST); \
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__tmp; \
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})
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#define atomic_op_locked_add +=
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#define atomic_op_locked_sub -=
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#define atomic_op_locked_or |=
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#define atomic_op_locked_xor ^=
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#define atomic_op_locked_and &=
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#define atomic_op_locked(RMW, OP, OPERAND, ORIG) \
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(atomic_lock__(RMW), \
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*(ORIG) = *(RMW), \
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*(RMW) atomic_op_locked_##OP (OPERAND), \
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atomic_unlock__(RMW))
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