mutex held in a thread which is cancelled stays busy
mafsys1234 at gmail.com
Wed Aug 7 04:39:24 UTC 2019
Sorry scratch that, I got confused. Doing 3 things at once.
On 7/08/2019 2:32 pm, MJ wrote:
> I just noticed this:
> pthread_mutexattr_getrobust (& Attr, &pres);
> Why are you passing &pres? It should be the address of
> PTHREAD_MUTEX_ROBUST (or PTHREAD_MUTEX_STALLED ?)
> I would expect you should get EINVAL when testing the above statement.
> The Freebsd manual says:
> "If successful, these functions return 0."
> Refer: PTHREAD_MUTEXATTR(3)
> On 7/08/2019 11:55 am, Erich Dollansky wrote:
>> On Tue, 6 Aug 2019 20:58:30 -0400
>> Daniel Eischen <deischen at freebsd.org> wrote:
>>>> On Aug 6, 2019, at 4:54 AM, Erich Dollansky
>>>> <freebsd.ed.lists at sumeritec.com> wrote:
>>>> 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
>>>> 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?
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