>On Friday, February 28, 2014 11:26 AM, Ian Abbott <abbotti@xxxxxxxxx> wrote: >>On 2014-02-28 07:35, Chase Southwood wrote: >> Smatch located a handful of while loops testing readl calls in s626.c. >> Since these while loops depend on readl succeeding, it's safer to make >> sure they time out eventually. >> >> Signed-off-by: Chase Southwood <chase.southwood@xxxxxxxxx> >> --- >> Ian and/or Hartley, I'd love your comments on this. It seems to me that >> we want these kinds of while loops properly timed out, but I want to make >> sure I'm doing everything properly. First off, s626_debi_transfer() says >> directly that it is called from within critical sections, so I assume >> that means that the new comedi_timeout() function is no good here, and >> s626_send_dac() looked equally suspicious, so I opted for iterative >> timeouts. Is this correct? Also, for these timeouts, I used a very >> conservative 10000 iterations, would it be better to decrease that? > >Well 10000 iterations is an improvement on infinity! If the hardware is >working, you'd expect it to go round a lot fewer iterations than that, >but if the hardware is broken all bets are off, especially if it is >generating interrupts. > Great, thanks! I suppose I'll leave that number there then. > >> Also, do my error strings appear acceptable? > >Mostly. There's a type in one of the strings that says "TLS" instead of >"TSL". > *Sigh* I promise I can type sometimes :P I'll get this corrected. > >> And finally, are timeouts here even necessary or helpful, or are there >> any better ways to do it? > >In the case of s626_send_dac(), it doesn't seem to be used in any >critical sections, so it could make use of Hartley's comedi_timeout(). > >Some of the timeout errors could be propagated, especially for >s626_send_dac() which is only reachable from very few paths. > Awesome, I'll swap all of my timeouts out for comedi_timeout() in s626_send_dac(). As for propagating the timeout errors, could you please clarify that a bit further? Both of the functions which I add timeouts inside of in this patch return void, and so in their current state they cannot return any error values. Would you like them (or at least s626_send_dac()) to instead return an error upon timeout/or success on success, or am I just totally misunderstanding your meaning of propagate here? > >There are other infinite loops involving calls to the s626_mc_test() >function, but those could be dealt with by other patches. > Yeah, I saw those...I'll whip up a patch for them, just wanted to verify that everything looks pretty good here before I started on that. I'll have that right out! Thanks, Chase > >-- >-=( Ian Abbott @ MEV Ltd. E-mail: <abbotti@xxxxxxxxx> )=- >-=( Tel: +44 (0)161 477 1898 FAX: +44 (0)161 718 3587 )=- _______________________________________________ devel mailing list devel@xxxxxxxxxxxxxxxxxxxxxx http://driverdev.linuxdriverproject.org/mailman/listinfo/driverdev-devel
