mirror of
https://github.com/Telecominfraproject/OpenCellular.git
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03d4ed278d
Basically re-use the gec lock code from flashrom package.
BUG=chrome-os-partner:12319
TEST=Build and run on link. Only build on snow.
while true; do ectool hello; done & ; run 10 instances.
; expect all instances runs okay.
Signed-off-by: Louis Yung-Chieh Lo <yjlou@chromium.org>
Change-Id: I11d5824f46810c6f5a04a564a81387cdea081697
Reviewed-on: https://gerrit.chromium.org/gerrit/29763
Reviewed-by: Randall Spangler <rspangler@chromium.org>
155 lines
4.3 KiB
C
155 lines
4.3 KiB
C
/*
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* Copyright 2003 Sun Microsystems, Inc.
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* Copyright 2010 Google, Inc.
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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 are
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* met:
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*
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* * 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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* * Redistributions in binary form must reproduce the above
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* copyright notice, this list of conditions and the following disclaimer
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* in the documentation and/or other materials provided with the
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* distribution.
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* * Neither the name of Google Inc. nor the names of its
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* contributors may be used to endorse or promote products derived from
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* this software without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
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* OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
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* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*
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* Developer's note: This was open sourced by Sun Microsystems, which got it
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* via Cobalt Networks. It has been fairly extensively modified since then.
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*/
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#ifndef CSEM_H__
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#define CSEM_H__
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#include <sys/ipc.h>
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#include <time.h>
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/* create a private key */
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#define CSEM_PRIVATE IPC_PRIVATE
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/*
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* Create a new semaphore with the specified key, initialized to the
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* specified value. If the key is CSEM_PRIVATE, a new private semaphore
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* is allocated.
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*
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* Returns the sempahore ID (>= 0) on success.
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* Returns < 0 on error, or if the key already exists.
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*/
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extern int csem_create(key_t key, unsigned val);
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/*
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* Fetch an existing semaphore with the specified key.
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*
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* Returns the sempahore ID (>= 0) on success.
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* Returns < 0 on error, or if the key does not exist.
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*/
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extern int csem_get(key_t key);
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/*
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* Fetch or create a semaphore with the specified key. If the semaphore
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* did not exist, it will be created with the specified value.
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*
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* Returns the sempahore ID (>= 0) on success.
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* Returns < 0 on error.
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*/
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extern int csem_get_or_create(key_t key, unsigned val);
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/*
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* Destroy the semaphore.
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*
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* Returns 0 on success.
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* Returns < 0 on error.
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*/
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extern int csem_destroy(int sem_id);
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/*
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* Get the value of the semaphore.
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*
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* Returns the value (>= 0) on success.
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* Returns < 0 on error.
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*/
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extern int csem_getval(int sem_id);
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/*
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* Set the value of the semaphore.
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*
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* Returns 0 on success.
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* Returns < 0 on error.
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*/
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extern int csem_setval(int sem_id, unsigned val);
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/*
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* Increment the semaphore.
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*
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* Returns 0 on success.
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* Returns < 0 on error.
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*/
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extern int csem_up(int sem_id);
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/*
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* Increment the semaphore. This operation will be undone when the
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* process terminates.
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*
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* Returns 0 on success.
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* Returns < 0 on error.
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*/
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extern int csem_up_undo(int sem_id);
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/*
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* Decrement the semaphore, or block if sem == 0.
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*
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* Returns 0 on success.
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* Returns < 0 on error.
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*/
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extern int csem_down(int sem_id);
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/*
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* Decrement the semaphore, or block if sem == 0. This operation will be
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* undone when the process terminates.
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*
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* Returns 0 on success.
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* Returns < 0 on error.
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*/
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extern int csem_down_undo(int sem_id);
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/*
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* Decrement the semaphore, or block with a timeout if sem == 0.
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*
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* Returns 0 on success.
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* Returns < 0 on error.
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*/
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extern int csem_down_timeout(int sem_id, struct timespec *timeout);
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/*
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* Decrement the semaphore, or block with a timeout if sem == 0. This
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* operation will be undone when the process terminates.
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*
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* Returns 0 on success.
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* Returns < 0 on error.
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*/
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extern int csem_down_timeout_undo(int sem_id, struct timespec *timeout);
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/*
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* Get the timestamp of the last csem_up()/csem_down() call.
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*
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* Returns sem_otime on success.
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* Returns < 0 on error
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*/
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extern time_t csem_get_otime(int sem_id);
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#endif /* CSEM_H__ */
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