Date: Wed, 7 Aug 2019 09:55:21 +0800 From: Erich Dollansky <freebsd.ed.lists@sumeritec.com> To: Daniel Eischen <deischen@freebsd.org> Cc: freebsd-threads@freebsd.org, freebsd-questions@freebsd.org Subject: Re: mutex held in a thread which is cancelled stays busy Message-ID: <20190807095521.23e79874.freebsd.ed.lists@sumeritec.com> In-Reply-To: <1FC05CEB-982F-484F-9E41-5A74FF564494@freebsd.org> References: <20190806165429.14bc4052.freebsd.ed.lists@sumeritec.com> <1FC05CEB-982F-484F-9E41-5A74FF564494@freebsd.org>
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Hi, On Tue, 6 Aug 2019 20:58:30 -0400 Daniel Eischen <deischen@freebsd.org> wrote: > > On Aug 6, 2019, at 4:54 AM, Erich Dollansky > > <freebsd.ed.lists@sumeritec.com> wrote: > > > > Hi, > > > > for testing purpose, I did the following. > > > > Start a thread, initialise a mutex in a global variable, lock the > > mutex and wait in that thread. > > > > Wait in the main program until above's thread waits and cancel it. > > > > Clean up behind the cancelled thread but leave intentional the mutex > > locked. > > > > I would have expected now to get an error like 'EOWNERDEAD' doing > > operations with that mutex. But I get 'EBUSY' as the error. > > Are you initializing the mutex as a robust mutex, via > pthread_mutexattr_setrobust()? Are you using _lock() or _trylock()? > > For _trylock(), you only get EOWNERDEAD for robust mutexes. It seems > that you should get EOWNERDEAD for _lock() in this case, so if that's > what you're doing, it sounds like it might be a bug. > I did both. One time with initialising the mutex with its defaults by handing over NULL as the attribute setting and one time with the attributes set. I use this line to set the attribute: pres = pthread_mutexattr_setrobust (& Attr, PTHREAD_MUTEX_ROBUST); The following line: pthread_mutexattr_getrobust (& Attr, &pres); Sets pres also to 1. I am doing this on 12.0-STABLE FreeBSD 12.0-STABLE r350391 GENERIC amd64 with the systems standard compiler. Is this the corrent way of doing it? Erich
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