deadlock - Critical section negative lock count

Question

I am debugging a deadlock issue and call stack shows that threads are waiting on some events.

Code is using critical section as synchronization primitive I think there is some issue here. Also the debugger is pointing to a critical section that is owned by some other thread,but lock count is -2. As per my understanding lock count>0 means that critical section is locked by one or more threads.

So is there any possibility that I am looking at right critical section which could be the culprit in deadlock.

In what scenarios can a critical section have negative lock count?

Answer 1

Beware: since Windows Server 2003 (for client OS this is Vista and newer) the meaning of LockCount has changed and -2 is a completely normal value, commonly seen when a thread has entered a critical section without waiting and no other thread is waiting for the CS. See Displaying a Critical Section:

In Microsoft Windows Server 2003 Service Pack 1 and later versions of Windows, the LockCount field is parsed as follows:

• The lowest bit shows the lock status. If this bit is 0, the critical section is locked; if it is 1, the critical section is not locked.
• The next bit shows whether a thread has been woken for this lock. If this bit is 0, then a thread has been woken for this lock; if it is 1, no thread has been woken.
• The remaining bits are the ones-complement of the number of threads waiting for the lock.