-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 Darren Hart wrote: > On Thu, 2008-05-29 at 16:46 -0700, Stephen Hemminger wrote: >> On Thu, 29 May 2008 23:41:55 +0000 >> Darren Hart <dvhltc@xxxxxxxxxx> wrote: >> >>> I find I need to be able to break out of the blocked state while waiting >>> to acquire a pthread_mutex. I'm using PI mutexes and want to continue >>> to do so. As I understand it, I can't use a signal to break out of the >>> lock as the man pages states: >>> >>> "If a signal is delivered to a thread waiting for a mutex, upon return >>> from the signal handler the thread shall resume waiting for the mutex >>> as if it was not interrupted." >>> >>> and that pthread_mutex_lock will not return EINTR. I had considered >>> using cond variables, but I don't think they will provide the same PI >>> behavior (since the threads are not blocked on the mutex while awaiting >>> the pthread_cond_signal - right?). >>> >>> I'm sure I'm not the first to want to do this, does anyone know of a >>> common best practice for accomplishing such a thing? >>> >> setjmp/longjmp? > > Stephen, > > Hrmm... I confess to not having made use of them before. I read up a > bit, and don't see right off how they would help in this situation. I > assume you're suggesting the longjmp be used in a signal handler while > the thread is blocked on the mutex - where would it jump to, and how > would I ensure the integrity of the pthread_mutex structure (which > thinks my thread is waiting for it) ? > I don't see any way to recover from longjmp'ing out of a pthread_mutex_lock(). Maybe using robust futexes and killing the thread that was blocked? I think it would be better to re-designed the code to use pthread_mutex_trylock() instead, so it doesn't block. That way you don't have a mutex in some wacky state. Clark -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.9 (GNU/Linux) Comment: Using GnuPG with Fedora - http://enigmail.mozdev.org iEYEARECAAYFAkhAHBQACgkQHyuj/+TTEp3dVgCeI8tNnbSDOLThVrUqjWcM9xPA mVgAnjR2D4RxIBXAjC+S2jtCdTaB+1AD =rmf4 -----END PGP SIGNATURE----- -- To unsubscribe from this list: send the line "unsubscribe linux-rt-users" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
