mirror of https://github.com/OISF/suricata
Introduce atomic operations API that supports GCC's atomic operations and a fallback using (spin)locks. Convert ringbuffer api to use the new atomic api.
Victor Julien
16 years ago
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/* Copyright (C) 2007-2010 Open Information Security Foundation
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*
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* You can copy, redistribute or modify this Program under the terms of
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* the GNU General Public License version 2 as published by the Free
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* Software Foundation.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* version 2 along with this program; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
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* 02110-1301, USA.
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*/
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/**
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* \file
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*
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* \author Victor Julien <victor@inliniac.net>
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*
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* API for atomic operations. Uses atomic instructions (GCC only at this time)
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* where available, falls back to (spin)locked* operations otherwise.
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*
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* To prevent developers from accidentally working with the atomic variables
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* directly instead of through the proper macro's, a marco trick is performed
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* that exposes different variable names than the developer uses. So if the dev
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* uses "somevar", internally "somevar_sc_atomic__" is used.
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*
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* Where available, we use __sync_fetch_and_add and
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* __sync_bool_compare_and_swap. If those are unavailable, the API
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* transparently created a matching (spin)lock for each atomic variable. The
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* lock will be named "somevar_sc_lock__"
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*
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* (*) where spinlocks are unavailable, the threading api falls back to mutex
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*/
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#ifndef __UTIL_ATOMIC_H__
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#define __UTIL_ATOMIC_H__
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/* test if we have atomic operations support */
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#ifndef __GCC_HAVE_SYNC_COMPARE_AND_SWAP_2
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/**
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* \brief wrapper to declare an atomic variable including a (spin) lock
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* to protect it.
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*
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* \warning Variable and lock are _not_ initialized.
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*/
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#define SC_ATOMIC_DECLARE(type, name) \
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type name ## _sc_atomic__; \
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SCSpinlock name ## _sc_lock__
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/**
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* \brief wrapper to declare an atomic variable including a (spin) lock
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* to protect it and initialize them.
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*/
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#define SC_ATOMIC_DECL_AND_INIT(type, name) \
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type name ## _sc_atomic__ = 0; \
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SCSpinlock name ## _sc_lock__; \
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SCSpinInit(&(name ## _sc_lock__), 0) \
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}
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/**
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* \brief Initialize the previously declared atomic variable and it's
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* lock.
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*/
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#define SC_ATOMIC_INIT(name) \
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SCSpinInit(&(name ## _sc_lock__), 0)
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/**
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* \brief Destroy the lock used to protect this variable
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*/
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#define SC_ATOMIC_DESTROY(name) \
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SCSpinDestroy(&(name ## _sc_lock__))
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/**
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* \brief add a value to our atomic variable
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*
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* \param name the atomic variable
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* \param val the value to add to the variable
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*/
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#define SC_ATOMIC_ADD(name, val) \
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do { \
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SCSpinLock(&(name ## _sc_lock__)); \
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(name ## _sc_atomic__) += (val); \
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SCSpinUnlock(&(name ## _sc_lock__)); \
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} while(0)
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/**
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* \brief Get the value from the atomic variable.
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*
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* \retval var value
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*/
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#define SC_ATOMIC_GET(name) ({ \
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typeof(name ## _sc_atomic__) var; \
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do { \
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SCSpinLock(&(name ## _sc_lock__)); \
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var = (name ## _sc_atomic__); \
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SCSpinUnlock(&(name ## _sc_lock__)); \
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} while (0); \
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var; \
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})
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/**
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* \brief atomic Compare and Switch
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*
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* \warning "name" is passed to us as "&var"
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*/
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#define SC_ATOMIC_CAS(name, cmpval, newval) ({ \
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char r = 0; \
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do { \
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SCSpinLock((name ## _sc_lock__)); \
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if (*(name ## _sc_atomic__) == (cmpval)) { \
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*(name ## _sc_atomic__) = (newval); \
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r = 1; \
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} \
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SCSpinUnlock((name ## _sc_lock__)); \
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} while(0); \
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r; \
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})
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#else /* we do have support for CAS */
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/**
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* \brief wrapper for OS/compiler specific atomic compare and swap (CAS)
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* function.
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*
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* \param addr Address of the variable to CAS
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* \param tv Test value to compare the value at address against
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* \param nv New value to set the variable at addr to
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*
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* \retval 0 CAS failed
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* \retval 1 CAS succeeded
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*/
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#define SCAtomicCompareAndSwap(addr, tv, nv) \
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__sync_bool_compare_and_swap((addr), (tv), (nv))
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/**
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* \brief wrapper for OS/compiler specific atomic fetch and add
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* function.
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*
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* \param addr Address of the variable to add to
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* \param value Value to add to the variable at addr
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*/
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#define SCAtomicFetchAndAdd(addr, value) \
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__sync_fetch_and_add((addr), (value))
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/**
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* \brief wrapper for declaring atomic variables.
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*
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* \warning Only char, short, int, long, long long and their unsigned
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* versions are supported.
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*
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* \param type Type of the variable (char, short, int, long, long long)
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* \param name Name of the variable.
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*
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* We just declare the variable here as we rely on atomic operations
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* to modify it, so no need for locks.
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*
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* \warning variable is not initialized
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*/
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#define SC_ATOMIC_DECLARE(type, name) \
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type name ## _sc_atomic__
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/**
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* \brief wrapper for declaring an atomic variable and initializing it.
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**/
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#define SC_ATOMIC_DECL_AND_INIT(type, name) \
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type name ## _sc_atomic__ = 0
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/**
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* \brief wrapper for initializing an atomic variable.
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**/
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#define SC_ATOMIC_INIT(name) \
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(name ## _sc_atomic__) = 0
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/**
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* \brief No-op.
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*/
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#define SC_ATOMIC_DESTROY(name)
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/**
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* \brief add a value to our atomic variable
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*
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* \param name the atomic variable
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* \param val the value to add to the variable
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*/
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#define SC_ATOMIC_ADD(name, val) \
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SCAtomicFetchAndAdd(&(name ## _sc_atomic__), (val));
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/**
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* \brief atomic Compare and Switch
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*
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* \warning "name" is passed to us as "&var"
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*/
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#define SC_ATOMIC_CAS(name, cmpval, newval) \
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SCAtomicCompareAndSwap((name ## _sc_atomic__), cmpval, newval)
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/**
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* \brief Get the value from the atomic variable.
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*
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* \retval var value
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*/
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#define SC_ATOMIC_GET(name) \
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(name ## _sc_atomic__)
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#endif /* !no atomic operations */
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#endif /* __UTIL_ATOMIC_H__ */
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