[linux-dvb] Re: dvb-kernel budget tests

[Emard <emard@softhome.net>]

> at the very beginning, alevt-date not at all.
> I'll see if I can hack something else together tomorrow. 

I see. Some quick crash test example would be nice to have .

> Note that this also can only happen if another process is just 
> allocating/setting/changing a filter and in just that moment when
> it has downed the semaphore in dvb_demux.c the softirq 
> which handles the networking is triggered and calls the
> set_multicast_list() function in dvb_net.

Can we introduce some crash patch, some mdelay() in the 
driver code after downing of the semaphore to magnify the problem?

> Then, the call which sets the section filter for the multicast 
> list will use a down_interruptible() in dvb_demux.c which will 
> fail and thus call schedule() which causes an oops in schedule() 
> because set_multicast_list() is called during interrupt.
> Also cf. /usr/src/linux/Documentation/networking/netdevices.txt
> which states that sleeping is not allowed here. 
> 
> 
>  > dvb-kernel survived that test. Please post crashme
>  > code sample which can attempt to cause the oops for
>  > the budget modules.
> 
> This is of course a bug in the upper DVB layers and not the 
> budget modules.

I meant budget modules as whole system, let's compare stability
from user point of view, difference of using budget cards vs. av7110. 

Budgets can be affected by down_interruptible so we might
look for some workaround.

I must admit that I was seeing for long time this down_interruptible
calls all around the code and it doesn't look too good. 

Emard



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