From: Stanislaw Gruszka <sgruszka@redhat.com>
To: Dmitry Vyukov <dvyukov@google.com>
Cc: Andrey Konovalov <andreyknvl@google.com>,
Helmut Schaa <helmut.schaa@googlemail.com>,
Kalle Valo <kvalo@codeaurora.org>,
linux-wireless@vger.kernel.org, netdev <netdev@vger.kernel.org>,
LKML <linux-kernel@vger.kernel.org>,
Kostya Serebryany <kcc@google.com>,
syzkaller <syzkaller@googlegroups.com>
Subject: Re: usb/net/rt2x00: warning in rt2800_eeprom_word_index
Date: Mon, 16 Oct 2017 11:40:24 +0200 [thread overview]
Message-ID: <20171016094024.GD2553@redhat.com> (raw)
In-Reply-To: <CACT4Y+YLM-u7bMfRB=eu_pz1M9iDrY-Qmnho7Hw_Lh3M=LSeMQ@mail.gmail.com>
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@redhat.com> 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
next prev parent reply other threads:[~2017-10-16 9:40 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-10-09 17:50 usb/net/rt2x00: warning in rt2800_eeprom_word_index Andrey Konovalov
2017-10-12 7:25 ` Stanislaw Gruszka
2017-10-14 14:38 ` Dmitry Vyukov
2017-10-16 9:40 ` Stanislaw Gruszka [this message]
2017-10-16 12:19 ` Dmitry Vyukov
2017-10-19 8:25 ` Dmitry Vyukov
2017-10-16 10:27 ` Kalle Valo
2017-10-16 12:16 ` Dmitry Vyukov
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