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author | Corinna Vinschen <corinna@vinschen.de> | 2012-05-23 13:24:57 +0000 |
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committer | Corinna Vinschen <corinna@vinschen.de> | 2012-05-23 13:24:57 +0000 |
commit | 750329ae90b72713963e4236c17e7f0bd167e4a3 (patch) | |
tree | 084535a59f9dc796bb7d5c0e418508539418c1d1 /winsup/cygwin/thread.cc | |
parent | dacf4be3fa450920f16fe279e155e861f8cd258a (diff) | |
download | newlib-750329ae90b72713963e4236c17e7f0bd167e4a3.zip newlib-750329ae90b72713963e4236c17e7f0bd167e4a3.tar.gz newlib-750329ae90b72713963e4236c17e7f0bd167e4a3.tar.bz2 |
* thread.cc (pthread::precreate): Make sure mutex is recursive.
Explain why.
Diffstat (limited to 'winsup/cygwin/thread.cc')
-rw-r--r-- | winsup/cygwin/thread.cc | 14 |
1 files changed, 12 insertions, 2 deletions
diff --git a/winsup/cygwin/thread.cc b/winsup/cygwin/thread.cc index bb38ff3..7a914b2 100644 --- a/winsup/cygwin/thread.cc +++ b/winsup/cygwin/thread.cc @@ -431,8 +431,18 @@ pthread::precreate (pthread_attr *newattr) magic = 0; return; } - /* Change the mutex type to NORMAL to speed up mutex operations */ - mutex.set_type (PTHREAD_MUTEX_NORMAL); + /* This mutex MUST be recursive. Consider the following scenario: + - The thread installs a cleanup handler. + - The cleanup handler calls a function which itself installs a + cleanup handler. + - pthread_cancel is called for this thread. + - The thread's cleanup handler is called under mutex lock condition. + - The cleanup handler calls the subsequent function with cleanup handler. + - The function runs to completion, so it calls pthread_cleanup_pop. + - pthread_cleanup_pop calls pthread::pop_cleanup_handler which will again + try to lock the mutex. + - Deadlock. */ + mutex.set_type (PTHREAD_MUTEX_RECURSIVE); if (!create_cancel_event ()) magic = 0; } |