On Mon, Oct 16, 2017 at 11:40 AM, Stanislaw Gruszka <sgruszka@xxxxxxxxxx> wrote: > Hi Dmitry > > On Sat, Oct 14, 2017 at 04:38:03PM +0200, Dmitry Vyukov wrote: >> On Thu, Oct 12, 2017 at 9:25 AM, Stanislaw Gruszka <sgruszka@xxxxxxxxxx> wrote: >> > Hi >> > >> > On Mon, Oct 09, 2017 at 07:50:53PM +0200, Andrey Konovalov wrote: >> >> I've got the following report while fuzzing the kernel with syzkaller. >> >> >> >> On commit 8a5776a5f49812d29fe4b2d0a2d71675c3facf3f (4.14-rc4). >> >> >> >> I'm not sure whether this is a bug in the driver, or just a way to >> >> report misbehaving device. In the latter case this shouldn't be a >> >> WARN() call, since WARN() means bug in the kernel. >> > >> > This is about wrong EEPROM, which reported 3 tx streams on >> > non 3 antenna device. I think WARN() is justified and thanks >> > to the call trace I was actually able to to understand what >> > happened. >> > >> > In general I do not think WARN() only means a kernel bug, it >> > can be F/W or H/W bug too. >> >> Hi Stanislaw, >> >> Printing messages is fine. Printing stacks is fine. Just please make >> them distinguishable from kernel bugs and don't kill the whole >> possibility of automated Linux kernel testing. That's an important >> capability. > > We do not distinguish between bugs and other problems when WARN() is > used in (wireless) drivers, what I think is correct, taking comment from > include/asm-generic/bug.h : > > /* > * WARN(), WARN_ON(), WARN_ON_ONCE, and so on can be used to report > * significant issues that need prompt attention if they should ever > * appear at runtime. Use the versions with printk format strings > * to provide better diagnostics. > */ > > Historically we have BUG() to mark the bugs, but usage if it is not > recommended as it can kill the system, so for anything that can > be recovered in runtime - WARN() is recommended. > > Perhaps we can introduce another helper like PROBLEM() for marking > situations when something is wrong, but it is not a bug. However I'm > not even sure at what extent it can be used, since for many cases > if not the most, driver author can not tell apriori if the problem > is a bug in the driver or HW/FW misbehaviour (or maybe particular > issue can happen because of both). I will write a separate email to LKML. Thanks
