On 24/03/2021 20.24, Joe Perches wrote: > On Wed, 2021-03-24 at 18:33 +0100, Rasmus Villemoes wrote: >> On 24/03/2021 18.20, Joe Perches wrote: >> >>> >>> Maybe it's better to output non PTR_ERR %pe uses as decimal so this >>> sort of code would work. >> >> No, because that would leak the pointer value when somebody has >> accidentally passed a real kernel pointer to %pe. > > I think it's not really an issue. > > _All_ code that uses %p<foo> extensions need inspection anyway. There are now a bunch of sanity checks in place that catch e.g. an ERR_PTR passed to an extension that would derefence the pointer; enforcing that only ERR_PTRs are passed to %pe (or falling back to %p) is another of those safeguards. > It's already possible to intentionally 'leak' the ptr value > by using %pe, -ptr so I think that's not really an issue. > Huh, what? I assume -ptr is shorthand for (void*)-(unsigned long)ptr. How would that leak the value if ptr is an ordinary kernel pointer? That's not an ERR_PTR unless (unsigned long)ptr is < 4095 or so. If you want to print the pointer value just do %px. No need for silly games. What I'm talking about is preventing _un_intentionally leaking a valid kernel pointer value. So no, a non-ERR_PTR passed to %pe is not going to be printed as-is, not in decimal or hexadecimal or roman numerals. >> If the code wants a cute -EFOO string explaining what's wrong, what >> about "%pe", ERR_PTR(mux < 0 : mux : -ERANGE)? Or two separate error >> messages >> >> if (mux < 0) >> ... >> else if (mux >= ARRAY_SIZE()) >> ... > > Multiple tests, more unnecessary code, multiple format strings, etc... Agreed, I'm not really advocating for the latter; the former suggestion is IMO a pretty concise way of providing useful information in dmesg. Rasmus _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/dri-devel
