copy_to_user

[Nilesh Tayade]

Hi,

On Fri, 2010-12-24 at 11:37 +0530, Hemanth Kumar wrote:

>                 
>                 > >
>                 
>         The mutex initialization is missing. 
>         Adding  mutex_init(&timer); in the driver init will make it
>         work.
>         
>         Thanks,
>         Mukti
>         
>         
>         Hi All,
>         
>             Can anybody please share some idea ,why I am getting
>         segmentation fault & kernel oops,
>         
>         Regards,
> 

I tried it, and it seems adding mutex_init() works as Mukti mentioned. I
did get a kernel oops before (but no segfault). After adding
mutex_init() there is no oops/segfault. The code, however, is reading
the garbage, that needs to be fixed.

pun-nilesht-dt0:/home/nilesh/Documents/handson # !mknod
mknod /dev/mytimer c 300 0

pun-nilesht-dt0:/home/nilesh/Documents # dmesg 
[ 2193.684735] Register timer maj = 300

pun-nilesht-dt0:/home/nilesh/Documents/handson # ./my_app.o 
 a = -30048 
 b = -23975 
 c = 32582 
...

See the attachments in case something is missing the code.

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-- 
Thanks,
Nilesh
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