On 01.11.20 15:57, Oliver Hartkopp wrote:
> - linux-kernel@xxxxxxxxxxxxxxx
> + linux-can@xxxxxxxxxxxxxxx
>
> Wrong mailing list ...
>
> On 01.11.20 15:57, Vincent Mailhol wrote:
> > The variable 'frame' is declared on the stack and is reused at each
> > iteration of the while loop.
> >
> > If not flushed, garbage data from the previous iteration of the loop
> > could remain causing unexpected behavior. This is the case in DLC
> > random mode: the field frame.len8_dlc is not cleared when the dlc is
> > exactly 8 and the len8_dlc value of the previous iteration will be
> > sent again.
>
> Good catch! Thanks.
>
> > This can be observed by running 'cangen -8 can0'. Once a frame of DLC
> > in the range 9..15 is generated, no more frames of DLC 8 show out in
> > the log.
> >
> > Signed-off-by: Vincent Mailhol <mailhol.vincent@xxxxxxxxxx>
> > ---
> > cangen.c | 2 +-
> > 1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/cangen.c b/cangen.c
> > index ab8122c..d7392b6 100644
> > --- a/cangen.c
> > +++ b/cangen.c
> > @@ -384,7 +384,7 @@ int main(int argc, char **argv)
> > }
> >
> > while (running) {
> > - frame.flags = 0;
> > + memset(&frame, 0, sizeof(frame));
>
> But this patch breaks everything which is not in random mode.
>
> Analogue to frame.flags we just need to clear frame.len8_dlc
You are right! My patch was dumb.
