On 27.07.2022 19:42, Linus Torvalds wrote: > On Wed, Jul 27, 2022 at 9:17 AM Alexey Khoroshilov > <khoroshilov@xxxxxxxxx> wrote: >> >> We see a number of cases where WARNING is used to inform userspace that >> it is doing something wrong, e.g. >> https://elixir.bootlin.com/linux/v5.19-rc8/source/net/can/j1939/socket.c#L181 >> https://elixir.bootlin.com/linux/v5.19-rc8/source/drivers/video/fbdev/core/fbmem.c#L1023 > > That first case is entirely bogus. > > WARN_ON() should only be used for "This cannot happen, but if it does, > I want to know how we got here". > > But the second case is fine: Using "pr_warn()" is fine. A kernel > warning (without a backtrace) is a normal thing for something that is > deprecated or questionable, and you want to tell the user that "this > app is doing something wrong". Agree with the only note that I like the requirement: * Do not include "BUG"/"WARNING" in format strings manually to make * these conditions distinguishable from kernel issues. very much. Thank you, Alexey
