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>
107 lines
3.1 KiB
C
107 lines
3.1 KiB
C
/* Copyright 2012, Google Inc.
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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 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
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* disclaimer in the documentation and/or other materials provided
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* with the 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
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* from 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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#include <inttypes.h>
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#include <stdio.h>
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#include <time.h>
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#include "csem.h"
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#include "ipc_lock.h"
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static int lock_init(struct ipc_lock *lock)
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{
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if (lock->sem < 0) {
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/* get or create the semaphore, init to 1 if needed */
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int sem = csem_get_or_create(lock->key, 1);
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if (sem < 0) {
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return -1;
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}
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lock->sem = sem;
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}
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return 0;
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}
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static void msecs_to_timespec(int msecs, struct timespec *tmspec)
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{
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tmspec->tv_sec = msecs / 1000;
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tmspec->tv_nsec = (msecs % 1000) * 1000 * 1000;
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}
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int acquire_lock(struct ipc_lock *lock, int timeout_msecs)
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{
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int ret;
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struct timespec timeout;
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struct timespec *timeout_ptr;
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/* initialize the lock */
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if (lock_init(lock) < 0) {
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fprintf(stderr, "%s(): failed to init lock 0x%08x\n",
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__func__, (uint32_t)lock->key);
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return -1;
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}
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/* check if it is already held */
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if (lock->is_held) {
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return 1;
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}
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/* calculate the timeout */
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if (timeout_msecs >= 0) {
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timeout_ptr = &timeout;
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msecs_to_timespec(timeout_msecs, timeout_ptr);
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} else {
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timeout_ptr = NULL;
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}
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/* try to get the lock */
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ret = csem_down_timeout_undo(lock->sem, timeout_ptr);
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if (ret < 0) {
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fprintf(stderr, "%s(): failed to acquire lock 0x%08x\n",
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__func__, (uint32_t)lock->key);
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return -1;
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}
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/* success */
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lock->is_held = 1;
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return 0;
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}
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int release_lock(struct ipc_lock *lock)
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{
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if (lock->is_held) {
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lock->is_held = 0;
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csem_up_undo(lock->sem);
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/* NOTE: do not destroy the semaphore, we want it to persist */
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return 0;
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}
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/* did not hold the lock */
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return -1;
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}
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