diff options
Diffstat (limited to 'libpod/lock/shm_lock.c')
| -rw-r--r-- | libpod/lock/shm_lock.c | 18 |
1 files changed, 16 insertions, 2 deletions
diff --git a/libpod/lock/shm_lock.c b/libpod/lock/shm_lock.c index ab715891c..48fd4d4a9 100644 --- a/libpod/lock/shm_lock.c +++ b/libpod/lock/shm_lock.c @@ -321,7 +321,8 @@ int32_t lock_semaphore(shm_struct_t *shm, uint32_t sem_index) { // subsequently realize they have been removed). // Returns 0 on success, -1 on failure int32_t unlock_semaphore(shm_struct_t *shm, uint32_t sem_index) { - int bitmap_index, index_in_bitmap; + int bitmap_index, index_in_bitmap, ret_code; + unsigned int sem_value = 0; if (shm == NULL) { return -1 * EINVAL; @@ -334,7 +335,20 @@ int32_t unlock_semaphore(shm_struct_t *shm, uint32_t sem_index) { bitmap_index = sem_index / BITMAP_SIZE; index_in_bitmap = sem_index % BITMAP_SIZE; - sem_post(&(shm->locks[bitmap_index].locks[index_in_bitmap])); + // Only allow a post if the semaphore is less than 1 (locked) + // This allows us to preserve mutex behavior + ret_code = sem_getvalue(&(shm->locks[bitmap_index].locks[index_in_bitmap]), &sem_value); + if (ret_code != 0) { + return -1 * errno; + } + if (sem_value >= 1) { + return -1 * EBUSY; + } + + ret_code = sem_post(&(shm->locks[bitmap_index].locks[index_in_bitmap])); + if (ret_code != 0) { + return -1 * errno; + } return 0; } |