8183f2e312
Convert filemon_lock and struct filemon* lock to sx(9), rather than a self-rolled reader-writer lock, and hold it for the entire time needed. At least filemon_lock_write() was not checking for active readers when it would successfully return with the write lock "held". This led to a race with reading entries from filemon_inuse as they were removed. This could be seen with QUEUE_MACRO_DEBUG enabled, causing -1 to be read as an entry rather than a valid struct filemon*. Fixing filemon_lock_write() to check readers was insufficient to fix the races. sx(9) was used as the lock could be held while taking proctree_lock and sleeping in fo_write. Sponsored by: EMC / Isilon Storage Division MFC after: 2 weeks
72 lines
1.9 KiB
C
72 lines
1.9 KiB
C
/*-
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* Copyright (c) 2009-2011, Juniper Networks, Inc.
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* Copyright (c) 2015, EMC Corp.
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY JUNIPER NETWORKS AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL JUNIPER NETWORKS OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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#include <sys/cdefs.h>
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__FBSDID("$FreeBSD$");
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static __inline void
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filemon_filemon_lock(struct filemon *filemon)
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{
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sx_xlock(&filemon->lock);
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}
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static __inline void
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filemon_filemon_unlock(struct filemon *filemon)
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{
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sx_xunlock(&filemon->lock);
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}
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static __inline void
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filemon_lock_read(void)
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{
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sx_slock(&access_lock);
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}
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static __inline void
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filemon_unlock_read(void)
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{
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sx_sunlock(&access_lock);
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}
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static __inline void
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filemon_lock_write(void)
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{
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sx_xlock(&access_lock);
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}
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static __inline void
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filemon_unlock_write(void)
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{
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sx_xunlock(&access_lock);
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}
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