On Sun, 2022-06-26 at 13:19 -0700, Linus Torvalds wrote: > On Sun, Jun 26, 2022 at 12:53 PM Joe Perches <joe@xxxxxxxxxxx> wrote: > > > > In a reply to the printbufs thread, I wrote a proposal to use an > > alloc to reduce stack in vsprintf when CONFIG_KALLSYMS is enabled. > > > > No one has replied to this but I think it's somewhat sensible. > > I think that's a bad idea. Somewhat sensible not sensible... > Those things are *literally* called from panic situations, which may > be while holding core memory allocation locks, or similar. True, and special_hex_number was used on alloc failure. > Now, you are correct that the stack buffer is annoying. But I think > the proper way to fix that is to say "we already *have* the target > buffer, let's use it". OK, and that's true for all the temp stack buffers in every %p<foo>. > That does require teaching the sprint_symbol() functions that they > need to take a "length of buffer" and return how much they used, but > that would seem to be a sensible thing anyway, and what the code > should always have done? Unnecessary stack and/or unnecessary buffers for printbufs are just unnecessary. > It's bad policy to just pass in a buffer without length, and I think > it was always broken. Nasty. That KSYM_SYMBOL_LEN is magically taking > care of it all, but it's ugly as heck, wouldn't you say? Yup.
