Am 06.07.2013 10:43, schrieb Gianluca Anzolin: > Hi, > > I'm getting panics and OOPS with the vanilla kernel 3.10 using rfcomm with a > bluetooth module connected to a microcontroller: this occurs when I poweroff > the microcontroller without closing first the rfcomm device. > > Searching the web I found that I'm not alone with this issue: > > http://marc.info/?l=linux-bluetooth&m=136868678418771&w=2 > > In the thread the issue seems to be a refcounting problem. > > Indeed looking at the source there are places where dev->port.tty is accessed > directly without taking references of the tty_struct. > > So I inspected every dev->port.tty access and changed the code to use > tty_port_tty_get which gets the references properly. > > In other places I used directly the tty_port_* helpers already in place. > > I the process I changed also the tty_port_hangup helper because it seems to me > that it could leak references in some cases (I sent another email for that). > > I attach the patch against net/bluetooth/rfcomm/tty.c and > drivers/tty/tty_port.c > > With this patch I cannot reproduce the oopses I was getting before: I was able > to trigger the panics very easily and now I cannot trigger them anymore. The patches with BUG_ON or WARN_ON don't work with 3.10 anymore and do make things worse, at least here. They are fine for 3.7-3.9, but not with 3.10. > > I cannot tell however if the problem is really fixed so I'm here request for > comments from people who know this code better than me. I've just had the chance to test a 3.10(.0) kernel with your two patches applied, they doesn't seem to help. The machine I've used to test just stood still after the first or second disconnect. Unfortunatley I can't provide any debug output, the machine I've just used doesn't have a serial and without debugging such stuff is a pain. > To them I'd like also to have a look at rfcomm_tty_close: in some situations > tty_port_put could be called two times: is that right? That doesn't sound sane. Regards, Alexander Holler -- To unsubscribe from this list: send the line "unsubscribe linux-serial" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
