| /* Copyright 2012, Google Inc. |
| * All rights reserved. |
| * |
| * Redistribution and use in source and binary forms, with or without |
| * modification, are permitted provided that the following conditions are |
| * met: |
| * |
| * * Redistributions of source code must retain the above copyright |
| * notice, this list of conditions and the following disclaimer. |
| * * Redistributions in binary form must reproduce the above |
| * copyright notice, this list of conditions and the following |
| * disclaimer in the documentation and/or other materials provided |
| * with the distribution. |
| * * Neither the name of Google Inc. nor the names of its |
| * contributors may be used to endorse or promote products derived |
| * from this software without specific prior written permission. |
| * |
| * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS |
| * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT |
| * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR |
| * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT |
| * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, |
| * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT |
| * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, |
| * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY |
| * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT |
| * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE |
| * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
| */ |
| |
| #include <inttypes.h> |
| #include <time.h> |
| |
| #include "mosys/ipc_lock.h" |
| #include "mosys/log.h" |
| |
| #include "csem.h" |
| |
| /* |
| * this function is exposed (non-static) for testing |
| */ |
| int |
| mosys_lock_is_held(struct ipc_lock *lock) |
| { |
| if (lock->is_held) { |
| return 1; |
| } |
| return 0; |
| } |
| |
| static int |
| lock_init(struct ipc_lock *lock) |
| { |
| if (lock->sem < 0) { |
| /* get or create the semaphore, init to 1 if needed */ |
| int sem = csem_get_or_create(lock->key, 1); |
| if (sem < 0) { |
| return -1; // COV_NF_LINE |
| } |
| lock->sem = sem; |
| } |
| return 0; |
| } |
| |
| static void |
| msecs_to_timespec(int msecs, struct timespec *tmspec) |
| { |
| tmspec->tv_sec = msecs / 1000; |
| tmspec->tv_nsec = (msecs % 1000) * 1000 * 1000; |
| } |
| |
| /* |
| * mosys_lock - acquire a lock |
| * |
| * timeout <0 = no timeout (try forever) |
| * timeout 0 = do not wait (return immediately) |
| * timeout >0 = wait up to $timeout milliseconds |
| * |
| * returns 0 to indicate lock acquired |
| * returns >0 to indicate lock was already held |
| * returns <0 to indicate failed to acquire lock |
| */ |
| int |
| mosys_lock(struct ipc_lock *lock, int timeout_msecs) |
| { |
| int ret; |
| struct timespec timeout; |
| struct timespec *timeout_ptr; |
| |
| /* initialize the lock */ |
| if (lock_init(lock) < 0) { |
| lperror(LOG_ERR, "failed to init lock 0x%08x", // COV_NF_LINE |
| (uint32_t)lock->key); // COV_NF_LINE |
| return -1; // COV_NF_LINE |
| } |
| |
| /* check if it is already held */ |
| if (mosys_lock_is_held(lock)) { |
| return 1; |
| } |
| |
| /* calculate the timeout */ |
| if (timeout_msecs >= 0) { |
| timeout_ptr = &timeout; |
| msecs_to_timespec(timeout_msecs, timeout_ptr); |
| } else { |
| timeout_ptr = NULL; |
| } |
| |
| /* try to get the lock */ |
| ret = csem_down_timeout_undo(lock->sem, timeout_ptr); |
| if (ret < 0) { |
| lperror(LOG_ERR, "failed to acquire lock 0x%08x", |
| (uint32_t)lock->key); |
| return -1; |
| } |
| |
| /* success */ |
| lock->is_held = 1; |
| return 0; |
| } |
| |
| /* |
| * mosys_unlock - release a lock |
| * |
| * returns 0 if lock was released successfully |
| * returns -1 if lock had not been held before the call |
| */ |
| int |
| mosys_unlock(struct ipc_lock *lock) |
| { |
| if (mosys_lock_is_held(lock)) { |
| lock->is_held = 0; |
| csem_up_undo(lock->sem); |
| /* NOTE: do not destroy the semaphore, we want it to persist */ |
| return 0; |
| } |
| /* did not hold the lock */ |
| return -1; |
| } |