On Tuesday 16 May 2006 22:46, Trent Piepho wrote:
> On Tue, 16 May 2006, Johannes Stezenbach wrote:
> > dvb_unregister_frontend():
> > ...
> >
> > + while(fe->ops->release) {
> > + struct module *m = fe->ops->release(fe);
> > + if (m)
> > + module_put(m);
> > + }
> > +
> >
> > - this way of chaining release() looks just sick
> > (is it even legal C code? can the optimizer not optimize
> > away the fe->ops->release register reload and turn this
> > into an endless loop?)
> > - the module_put() in there is just as wrong as doing
> > the module_put() inside release()
>
> Besides that, it has a bug. It will access memory that has been
> kfree()'d. See my message here:
> http://www.linuxtv.org/pipermail/linux-dvb/2006-May/010159.html
>
> In that message I posted an example of something that will work, with
> just the core change, plus two example demod changes.
Ah yup I get you. OK, we can use that if we decide to go that way.
In the meantime, I've done a partial version with js's suggestions - it is at
http://linuxtv.org/hg/~quincy/v4l-dvb-attach
This removes chaining, and adds support for the SEC devices into the
frontend_ops. I have not implemented any frontend changes yet.
Also: there are no symbol_put_addrs() done yet. I've not yet had time to think
on how do to do that - any suggestions? We could use a dvb_detach as js
suggests, passing it the release() pointer to detach and then call
symbol_put_adddr.
I'm just uploading the previous tree to
http://linuxtv.org/hg/~quincy/v4l-dvb-attach-old.
Here is a first stab at dvb_detach (sorry if you already posted one johannes;
I have zapped the message :(
#define dvb_detach(FUNCTION, FE) \
do { \
if (FUNCTION) { \
FUNCTION(FE); \
symbol_put_addr(FUNCTION); \
} \
} while(0);
We could either make the card drivers call this directly, or (for convenience)
call it from dvb_unregister_frontend() instead of directly calling the
release() methods like we do just now
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