Re: [PATCH] Avoid sysfs oops when an rc_dev's raw device is absent

[Douglas Bagnall <douglas@paradise.net.nz>]

hi,

I probably should have sent that in reply to 
http://article.gmane.org/gmane.linux.drivers.video-input-infrastructure/49740
which is the problem it fixes.

Some things which might be of interest:

1. I innocently followed the instructions on
   http://www.linuxtv.org/wiki/index.php/Maintaining_Git_trees (i.e.,
   use v4l-dvb tree on top of linus tree) and spent a while looking at
   IR/ir-sysfs.c instead of rc/rc-main.c. How stable it seemed! no
   patches in years! So I added a warning at the top of the wiki page,
   though a fix from someone who knows would be preferable.

2. From the above, I ended up reading a lot of ancient history and saw
   that this was inadvertently sort of fixed for a few weeks in 2010
   between a08c7c68f702e2a2797a4035b and d8b4b5822f51e2142b731b42.

3. I wrote:

> This patch avoids the NULL dereference, and ignores the issue of how
> this state of affairs came about in the first place.

Would, in rc_unregister_device(), putting device_del(&dev->dev) before
ir_raw_event_unregister(dev) help? I've only been a kernel hacker for
two hours so I am honestly clueless, but it seems like that might
avert the race by hiding the structure from sysfs before it is pulled
apart.

regards,

Douglas