Date: Wed, 7 Aug 2019 17:36:40 +0800 From: Erich Dollansky <freebsd.ed.lists@sumeritec.com> To: Konstantin Belousov <kostikbel@gmail.com> Cc: Daniel Eischen <deischen@freebsd.org>, freebsd-questions@freebsd.org, freebsd-threads@freebsd.org Subject: Re: mutex held in a thread which is cancelled stays busy Message-ID: <20190807173640.0b2e3aa8.freebsd.ed.lists@sumeritec.com> In-Reply-To: <20190807092035.GG2731@kib.kiev.ua> References: <20190806165429.14bc4052.freebsd.ed.lists@sumeritec.com> <1FC05CEB-982F-484F-9E41-5A74FF564494@freebsd.org> <20190807071002.GF2731@kib.kiev.ua> <20190807163757.2b5d52fa.freebsd.ed.lists@sumeritec.com> <20190807092035.GG2731@kib.kiev.ua>
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Hi, On Wed, 7 Aug 2019 12:20:35 +0300 Konstantin Belousov <kostikbel@gmail.com> wrote: > On Wed, Aug 07, 2019 at 04:37:57PM +0800, Erich Dollansky wrote: > > Hi, > > > > On Wed, 7 Aug 2019 10:10:02 +0300 > > Konstantin Belousov <kostikbel@gmail.com> wrote: > > > > > On Tue, Aug 06, 2019 at 08:58:30PM -0400, Daniel Eischen 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()? > > > Robust mutexes only have special properties on the process > > > termination. They behave same as the normal mutexes if the owning > > > thread is terminated. > > > > > man says: > > > > [EOWNERDEAD] The argument mutex points to a robust mutex and the > > previous owning thread terminated while holding the mutex lock. > > So what ? It describes the case when error can be returned, but it is > not required to do so. POSIX wording is the following: > what does POSIX matter when the manual of the operating system the program is running on states something else? Erich
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