Pthread_mutex_lock Error Codes

pthread_mutex_lock(pthread_mutex_t *mutex); int pthread_mutex_trylock(pthread_mutex_t *mutex); int pthread_mutex_unlock(pthread_mutex_t *mutex); DESCRIPTION The mutex object referenced by mutex is locked by calling pthread_mutex_lock(). If the mutex is already locked, the calling thread blocks until pthread_mutex_lock example the mutex becomes available. This operation returns with the mutex object

Pthread_mutex_lock Return Value

referenced by mutex in the locked state with the calling thread as its owner. If the mutex type man pthread_mutex_lock is PTHREAD_MUTEX_NORMAL, deadlock detection is not provided. Attempting to relock the mutex causes deadlock. If a thread attempts to unlock a mutex that it has not locked or

Pthread_mutex_trylock

a mutex which is unlocked, undefined behaviour results. If the mutex type is PTHREAD_MUTEX_ERRORCHECK, then error checking is provided. If a thread attempts to relock a mutex that it has already locked, an error will be returned. If a thread attempts to unlock a mutex that it has not locked or a mutex which is unlocked, an error pthread_mutex_unlock will be returned. If the mutex type is PTHREAD_MUTEX_RECURSIVE, then the mutex maintains the concept of a lock count. When a thread successfully acquires a mutex for the first time, the lock count is set to one. Every time a thread relocks this mutex, the lock count is incremented by one. Each time the thread unlocks the mutex, the lock count is decremented by one. When the lock count reaches zero, the mutex becomes available for other threads to acquire. If a thread attempts to unlock a mutex that it has not locked or a mutex which is unlocked, an error will be returned. If the mutex type is PTHREAD_MUTEX_DEFAULT, attempting to recursively lock the mutex results in undefined behaviour. Attempting to unlock the mutex if it was not locked by the calling thread results in undefined behaviour. Attempting to unlock the mutex if it is not locked results in undefined behaviour. The function pthread_mutex_trylock() is identical to pthread_mutex_lock() except that if the mutex object referenced by mutex is currently locked

the interface may not be implemented on Linux. Name pthread_mutex_lock, pthread_mutex_trylock, pthread_mutex_unlock - lock and unlock a mutex Synopsis #include int pthread_mutex_lock(pthread_mutex_t *mutex); int pthread_mutex_trylock(pthread_mutex_t *mutex); int pthread_mutex_unlock(pthread_mutex_t *mutex); Description The mutex object referenced by mutex shall be locked

Pthread_mutex_init

by calling pthread_mutex_lock(). If the mutex is already locked, the calling thread shall block until

Pthread_mutex_initializer

the mutex becomes available. This operation shall return with the mutex object referenced by mutex in the locked state with the calling thread pthread_mutex_recursive as its owner. If the mutex type is PTHREAD_MUTEX_NORMAL, deadlock detection shall not be provided. Attempting to relock the mutex causes deadlock. If a thread attempts to unlock a mutex that it has not locked or a mutex http://pubs.opengroup.org/onlinepubs/7908799/xsh/pthread_mutex_lock.html which is unlocked, undefined behavior results. If the mutex type is PTHREAD_MUTEX_ERRORCHECK, then error checking shall be provided. If a thread attempts to relock a mutex that it has already locked, an error shall be returned. If a thread attempts to unlock a mutex that it has not locked or a mutex which is unlocked, an error shall be returned. If the mutex type is PTHREAD_MUTEX_RECURSIVE, then the mutex shall maintain the concept of a https://linux.die.net/man/3/pthread_mutex_lock lock count. When a thread successfully acquires a mutex for the first time, the lock count shall be set to one. Every time a thread relocks this mutex, the lock count shall be incremented by one. Each time the thread unlocks the mutex, the lock count shall be decremented by one. When the lock count reaches zero, the mutex shall become available for other threads to acquire. If a thread attempts to unlock a mutex that it has not locked or a mutex which is unlocked, an error shall be returned. If the mutex type is PTHREAD_MUTEX_DEFAULT, attempting to recursively lock the mutex results in undefined behavior. Attempting to unlock the mutex if it was not locked by the calling thread results in undefined behavior. Attempting to unlock the mutex if it is not locked results in undefined behavior. The pthread_mutex_trylock() function shall be equivalent to pthread_mutex_lock(), except that if the mutex object referenced by mutex is currently locked (by any thread, including the current thread), the call shall return immediately. If the mutex type is PTHREAD_MUTEX_RECURSIVE and the mutex is currently owned by the calling thread, the mutex lock count shall be incremented by one and the pthread_mutex_trylock() function shall immediately return success. The pthread_mutex_unlock() function shall release the mutex object referenced by mutex. The manner in which a mutex is released is

here for a quick overview of the site Help Center Detailed answers to any questions you might have Meta Discuss the workings and policies of this site About Us Learn more about Stack Overflow the company Business Learn more about hiring developers or http://stackoverflow.com/questions/12781944/pthread-mutex-lock-returns-invalid-argument posting ads with us Stack Overflow Questions Jobs Documentation Tags Users Badges Ask Question x Dismiss Join the Stack Overflow Community Stack Overflow is a community of 6.2 million programmers, just like you, helping each other. Join them; it only takes http://manpages.ubuntu.com/manpages/wily/man3/pthread_mutex_lock.3.html a minute: Sign up pthread_mutex_lock returns invalid argument up vote 4 down vote favorite I am working on some C code and am having a problem with locking a mutex. The code does a call to a function and this function pthread_mutex_lock error locks a mutex to ensure a file pointer doesn't get overwritten, this works fine for several instances, probably about 10-20 separate calls of the function being called, but on the next call, pthread_mutex_lock will return with a result of 22. I've then put this result into strerror(); and got back invalid argument. What does invalid argument means, thanks for any help you can provide. c debugging pthreads mutex share|improve this question edited Oct 8 '12 at 12:43 vy32 9,0311661128 asked Oct pthread_mutex_lock error codes 8 '12 at 12:39 Boardy 9,90554168284 add a comment| 2 Answers 2 active oldest votes up vote 4 down vote accepted Sounds like you have a threading problem or a wild point somewhere else in your program. Try printing the value of the mutex pointer. Try having another thread that simply locks the mutex and then prints to a log file the time and that the lock was successful, then unlocks the mutex. I suspect the problem is not where you are looking. Also, as other have said here, your best bet is to create a very small test program that demonstrates the problem and post it here. Chances are you won't be able to get that small program to demonstrate the error. Then slowly add all of your original code into the small program until the error returns. If it returns, you now know what caused the problem. If it doesn't return, you're done. share|improve this answer answered Oct 8 '12 at 12:43 vy32 9,0311661128 add a comment| up vote 7 down vote 22 is ENVAL error code which means invlalid argument. Make sure that you have initilized you mutex, or if at some point you have unitilized it somewhere. Also man pthread_mutex_lock says: EINVAL The mutex was created with the protocol attribute having the value PTHREAD_PRIO_PROTECT and the calling thread's priority is higher than the mutex's current priority ceiling. I don't quite understand this but it probably means that you need

= PTHREAD_MUTEX_INITIALIZER; pthread_mutex_t recmutex = PTHREAD_RECURSIVE_MUTEX_INITIALIZER_NP; pthread_mutex_t errchkmutex = PTHREAD_ERRORCHECK_MUTEX_INITIALIZER_NP; int pthread_mutex_init(pthread_mutex_t *mutex, const pthread_mutexattr_t *mutexattr); int pthread_mutex_lock(pthread_mutex_t *mutex); int pthread_mutex_trylock(pthread_mutex_t *mutex); int pthread_mutex_unlock(pthread_mutex_t *mutex); int pthread_mutex_destroy(pthread_mutex_t *mutex); DESCRIPTION A mutex is a MUTual EXclusion device, and is useful for protecting shared data structures from concurrent modifications, and implementing critical sections and monitors. A mutex has two possible states: unlocked (not owned by any thread), and locked (owned by one thread). A mutex can never be owned by two different threads simultaneously. A thread attempting to lock a mutex that is already locked by another thread is suspended until the owning thread unlocks the mutex first. pthread_mutex_init initializes the mutex object pointed to by mutex according to the mutex attributes specified in mutexattr. If mutexattr is NULL, default attributes are used instead. The LinuxThreads implementation supports only one mutex attributes, the mutex kind, which is either ``fast'', ``recursive'', or ``error checking''. The kind of a mutex determines whether it can be locked again by a thread that already owns it. The default kind is ``fast''. See pthread_mutexattr_init(3) for more information on mutex attributes. Variables of type pthread_mutex_t can also be initialized statically, using the constants PTHREAD_MUTEX_INITIALIZER (for fast mutexes), PTHREAD_RECURSIVE_MUTEX_INITIALIZER_NP (for recursive mutexes), and PTHREAD_ERRORCHECK_MUTEX_INITIALIZER_NP (for error checking mutexes). pthread_mutex_lock locks the given mutex. If the mutex is currently unlocked, it becomes locked and owned by the calling thread, and pthread_mutex_lock returns immediately. If the mutex is already locked by another thread, pthread_mutex_lock suspends the calling thread until the mutex is unlock