Re: would a mutex_wait be useful?

[Matt Thomas <matt%3am-software.com@localhost>]

On Nov 4, 2008, at 3:50 AM, Mindaugas Rasiukevicius wrote:

> Matt Thomas <matt%3am-software.com@localhost> wrote:
> > I'd like to be able to do a mutex_enter(9) which could be  
> > interruptable.
> > If interrupted, it would return the error why it was interrupted.
>
> Where/when do you need interruptible mutex?

I was replacing code in arm32/mem.c with a home grown lock with  
mutex_enter.
Relatively easy to do except it no longer does PCATCH.

> > Maybe called int mutex_wait(kmutex_t *mtx, int ticks); and if  
> > ticks == 0
> > becomes (mutex_tryenter(mtx) ? 0 : ETIMEOUT).  If tick == -1, means
> > wait forever.
> >
> > mutex_wait would use PCATCH for its sleeps and return EINTR if a  
> > signal
> > was caught.
>
> That does not sound like a good API. If specific synchronisation is  
> needed,
> I think wrappers with mutex_tryenter() could be used for that.

Not easily.  And rolling your own seems wrong.  Hence the proposal  
for a common
method to do it.