On Fri, Jul 22, 2016 at 1:45 AM, Steve Muckle <steve.muc...@linaro.org> wrote: > On Fri, Jul 22, 2016 at 01:32:00AM +0200, Rafael J. Wysocki wrote: >> On Fri, Jul 22, 2016 at 1:22 AM, Steve Muckle <steve.muc...@linaro.org> >> wrote: >> > On Fri, Jul 22, 2016 at 01:22:22AM +0200, Rafael J. Wysocki wrote: >> >> OK, applied. >> > >> > FWIW I do have a concern on this patch, I think it adds unnecessary >> > overhead. >> >> It isn't unnecessary. It prevents an otherwise possible kernel crash >> from happening. > > The logic may not be unecessary, but the overhead is. The crash could be > prevented in a way that doesn't require repeatedly checking a pointer > that doesn't change.
Well, you had the ->resolve_freq check in your patch, didn't you? Viresh simply added a ->target_index check to it. Now, you can argue that this is one check too many, but as long as drivers are allowed to implement ->target without implementing ->resolve_freq, the *number* of checks in this routine cannot be reduced. There are three possible cases and two checks are required to determine which case really takes place.
