On Tue, 2009-01-06 at 14:49 -0200, Mauro Carvalho Chehab wrote:
> On Mon, 05 Jan 2009 19:46:40 -0500
> Andy Walls <awalls@xxxxxxxxx> wrote:
>
> > I you run across the oops often, then the suspected race condition in
> > the function I mentioned needs to be fixed. That may be as simple as
> > this lame patch:
>
> Could you please provide you your SOB?
diff -r ce8589c52a7f linux/drivers/media/video/cx88/cx88-mpeg.c
--- a/linux/drivers/media/video/cx88/cx88-mpeg.c Tue Jan 06 09:33:46 2009 -0200
+++ b/linux/drivers/media/video/cx88/cx88-mpeg.c Tue Jan 06 17:27:03 2009 +0100
@@ -830,6 +830,9 @@
err = cx8802_init_common(dev);
if (err != 0)
goto fail_free;
+ /* Maintain a reference so cx88-video can query the 8802 device. */
+ core->dvbdev = dev;
+
INIT_LIST_HEAD(&dev->drvlist);
list_add_tail(&dev->devlist,&cx8802_devlist);
@@ -851,20 +854,19 @@
__func__);
videobuf_dvb_dealloc_frontends(&dev->frontends);
err = -ENOMEM;
+ /* FIXME - need to pull dev off cx8802_devlist*/
goto fail_free;
}
}
}
#endif
- /* Maintain a reference so cx88-video can query the 8802 device. */
- core->dvbdev = dev;
-
/* now autoload cx88-dvb or cx88-blackbird */
request_modules(dev);
return 0;
fail_free:
+ /* FIXME - shouldn't we pull dev off the cx8802_devlist - oops */
kfree(dev);
fail_core:
cx88_core_put(core,pci_dev);
Signed-off-by: Andy Walls <awalls@xxxxxxxxx>
Mauro,
Please be aware that I am not happy with my own patch. The function
should really make sure everything is OK *before* putting the object on
the cx8802_devlist. The failure cases are "Oops"es waiting to happen:
the pointer is on the list, but the objects are deallocated in the
failure cases - not good. :P
> IMO, the proper fix would be to add some locking at cx88 init. I suspect that
> this breakage (and other similar ones) are tue to the absense of KBL on newer kernels.
Yes, locking somehow would probably be a good idea here. I haven't
looked at it though.
I have no cx88 based hardware with which to test.
I don't know. This looks like a race. New timing caused by a
signifcant amount of kernel changes could have caused it to trip more
frequently.
> Gregoire,
>
> What kernel version are you using?
>
> >
> > fail_free:
> > + /* FIXME - shouldn't we pull dev off the cx8802_devlist - oops */
>
> Better to add here:
> core->dvbdev = NULL;
Sure, but we still have the problem of pointers to deallocated objects
on the cx8802_devlist.
Regards,
Andy
>
>
>
> Cheers,
> Mauro
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