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). Thanks Stanislaw
