Feature #1940
Updated by Vadim Mutilin about 10 years ago
You should not acquire or release the same mutex twice in the same process. All locked mutexes should be unlocked at finalization. *Description* There are several things you should watch for: # *Double-locking.* Mutex-type object provides exclusive access to sections of executable code. Thus retrying to acquire the current mutex will inevitably lead to a deadlock-situation. Deadlocks should be avoided, hence no double locks should take place. # *Releasing an unlocked mutex.* # *Leaving a mutex locked* at finalization. Mutex is a special case of semaphore, restricted with just one possible requestor. However, it has its own wrapping functions. To initialize a mutex, macros are often used: DECLARE_MUTEX(name) and DECLARE_MUTEX_LOCKED(name). Locking is provided via mutex_lock(), mutex_trylock() and mutex_lock_interruptible() functions; unlocking--via mutex_unlock(). *Links* Sample bugfixes "4a349aa":https://git.kernel.org/cgit/linux/kernel/git/stable/linux-stable.git/commit/?id=4a349aa, "a9e7fb5":https://git.kernel.org/cgit/linux/kernel/git/stable/linux-stable.git/commit/?id=a9e7fb5, "d47b389":https://git.kernel.org/cgit/linux/kernel/git/stable/linux-stable.git/commit/?id=d47b389, "c1c7415":https://git.kernel.org/cgit/linux/kernel/git/stable/linux-stable.git/commit/?id=c1c7415, "8a9f335":https://git.kernel.org/cgit/linux/kernel/git/stable/linux-stable.git/commit/?id=8a9f335, "723342c":https://git.kernel.org/cgit/linux/kernel/git/stable/linux-stable.git/commit/?id=723342c, "c4cb1dd":https://git.kernel.org/cgit/linux/kernel/git/stable/linux-stable.git/commit/?id=c4cb1dd "723342c":https://git.kernel.org/cgit/linux/kernel/git/stable/linux-stable.git/commit/?id=723342c