On 08/11/16 21:38, Mauro Carvalho Chehab wrote:
Em Tue, 8 Nov 2016 22:15:24 +0100
Benjamin Larsson <benjamin@xxxxxxxxxxxx> escreveu:
On 11/08/2016 09:22 PM, Mauro Carvalho Chehab wrote:
Em Tue, 8 Nov 2016 10:42:03 -0800
Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx> escreveu:
On Sun, Nov 6, 2016 at 7:40 AM, Jörg Otte <jrg.otte@xxxxxxxxx> wrote:
Since v4.9-rc4 I get following crash in dvb-usb-cinergyT2 module.
Looks like it's commit 5ef8ed0e5608f ("[media] cinergyT2-core: don't
do DMA on stack"), which movced the DMA data array from the stack to
the "private" pointer. In the process it also added serialization in
the form of "data_mutex", but and now it oopses on that mutex because
the private pointer is NULL.
It looks like the "->private" pointer is allocated in dvb_usb_adapter_init()
cinergyt2_usb_probe ->
dvb_usb_device_init ->
dvb_usb_init() ->
dvb_usb_adapter_init()
but the dvb_usb_init() function calls dvb_usb_device_power_ctrl()
(which calls the "power_ctrl" function, which is
cinergyt2_power_ctrl() for that drive) *before* it initializes the
private field.
Mauro, Patrick, could dvb_usb_adapter_init() be called earlier, perhaps?
Calling it earlier won't work, as we need to load the firmware before
sending the power control commands on some devices.
Probably the best here is to pass an extra optional function parameter
that will initialize the mutex before calling any functions.
Btw, if it broke here, the DMA fixes will likely break on other drivers.
So, after Jörg tests this patch, I'll work on a patch series addressing
this issue on the other drivers I touched.
Regards,
Mauro
Just for reference I got the following call trace a week ago. I looks
like this confirms that other drivers are affected also.
Yeah, I avoided serializing the logic that detects if the firmware is
loaded, but forgot that the power control had the same issue. The
newer dvb usb drivers use the dvb-usb-v2, so I didn't touch this
code for a while.
I think the problem is that the usb buffer has been put in struct
cinergyt2_state private area which has not been initialized for initial
usb probing.
That was one of the main reasons for porting drivers to dvb-usb-v2.
Regards
Malcolm
--
To unsubscribe from this list: send the line "unsubscribe linux-media" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
