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From: Luis Chamberlain <mcgrof@kernel.org>
To: Steve deRosier <derosier@gmail.com>
Cc: Johannes Berg <johannes@sipsolutions.net>,
	Jakub Kicinski <kuba@kernel.org>,
	Ben Greear <greearb@candelatech.com>,
	jeyu@kernel.org, akpm@linux-foundation.org, arnd@arndb.de,
	rostedt@goodmis.org, mingo@redhat.com, aquini@redhat.com,
	cai@lca.pw, dyoung@redhat.com, bhe@redhat.com,
	peterz@infradead.org, tglx@linutronix.de, gpiccoli@canonical.com,
	pmladek@suse.com, Takashi Iwai <tiwai@suse.de>,
	schlad@suse.de, andriy.shevchenko@linux.intel.com,
	Kees Cook <keescook@chromium.org>,
	Daniel Vetter <daniel.vetter@ffwll.ch>,
	will@kernel.org, mchehab+samsung@kernel.org,
	Kalle Valo <kvalo@codeaurora.org>,
	"David S. Miller" <davem@davemloft.net>,
	Network Development <netdev@vger.kernel.org>,
	LKML <linux-kernel@vger.kernel.org>,
	linux-wireless <linux-wireless@vger.kernel.org>,
	ath10k@lists.infradead.org, jiri@resnulli.us,
	briannorris@chromium.org
Subject: Re: [RFC 1/2] devlink: add simple fw crash helpers
Date: Fri, 22 May 2020 23:44:09 +0000
Message-ID: <20200522234409.GH11244@42.do-not-panic.com> (raw)
In-Reply-To: <CALLGbR+QPcECtJbYmzztV_Qysc5qtwujT_qc785zvhZMCH50fg@mail.gmail.com>

On Fri, May 22, 2020 at 04:23:55PM -0700, Steve deRosier wrote:
> Specifically, I don't think we should set a taint flag when a driver
> easily handles a routine firmware crash and is confident that things
> have come up just fine again. In other words, triggering the taint in
> every driver module where it spits out a log comment that it had a
> firmware crash and had to recover seems too much. Sure, firmware
> shouldn't crash, sure it should be open source so we can fix it,
> whatever... those sort of wishful comments simply ignore reality and
> our ability to affect effective change. A lot of WiFi firmware crashes
> and for well-known cases the drivers handle them well. And in some
> cases, not so well and that should be a place the driver should detect
> and thus raise a red flag.  If a WiFi firmware crash can bring down
> the kernel, there's either a major driver bug or some very funky
> hardware crap going on. That sort of thing we should be able to
> detect, mark with a taint (or something), and fix if within our sphere
> of influence. I guess what it comes down to me is how aggressive we
> are about setting the flag.

Exactly the crux of the issue.

I hope that by now we should all be in agreement that at least a
firmware crash requiring a reboot is something we should record and
inform the user of. A taint seems like a reasonable standard practice
for these sorts of things.

> I would like there to be a single solution, or a minimized set
> depending on what makes sense for the requirements. I haven't had time
> to look into the alternatives mentioned here so I don't have an
> informed opinion about the solution. I do think Luis is trying to
> solve a real problem though. Can we look at this from the point of
> view of what are the requirements?  What is it we're trying to solve?
> 
> I _think_ that the goal of Luis's original proposal is to report up to
> the user, at some future point when the user is interested (because
> something super drastic just occured, but long after the fw crash),
> that there was a firmware crash without the user having to grep
> through all logs on the machine. And then if the user sees that flag
> and suspects it, then they can bother to find it in the logs or do
> more drastic debugging steps like finding the fw crash in the log and
> pulling firmware crash dumps, etc.

Yes, that's exactly it. Not all users are clueful to inspect logs. I now
have a generic uevent mechanism drafted which sends a uevent for *any*
taint. So that is, it does not even depend on this series. But it
accomplishes the goal of informing the user of taints.

> I think the various alternate solutions are great but perhaps solving
> a superset of features (like adding in user-space notifications etc)?
> Perhaps different people on these related threads are trying to solve
> different problems?

The uevent mechanism I implemented (but not yet posted for review) at
least sends out a smoke signal. I think that if each subsystem wants
to expand on this with dumping facilities that is great too!

  Luis

  reply index

Thread overview: 50+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <20200515212846.1347-1-mcgrof@kernel.org>
2020-05-15 21:28 ` [PATCH v2 12/15] ath10k: use new module_firmware_crashed() Luis Chamberlain
2020-05-16  4:11   ` Rafael Aquini
2020-05-16 13:24   ` Johannes Berg
2020-05-16 13:50     ` Johannes Berg
2020-05-18 16:56       ` Luis Chamberlain
2020-05-19  1:23       ` Brian Norris
2020-05-19 14:02         ` Luis Chamberlain
2020-05-20  0:47           ` Brian Norris
2020-05-20  5:37             ` Emmanuel Grumbach
2020-05-20  8:32               ` Andy Shevchenko
2020-05-21 19:01               ` Brian Norris
2020-05-22  5:12                 ` Emmanuel Grumbach
2020-05-22  5:23                   ` Luis Chamberlain
2020-05-18 16:51     ` Luis Chamberlain
2020-05-18 16:58       ` Ben Greear
2020-05-18 17:09         ` Luis Chamberlain
2020-05-18 17:15           ` Ben Greear
2020-05-18 17:18             ` Luis Chamberlain
2020-05-18 18:06               ` Steve deRosier
2020-05-18 19:09                 ` Luis Chamberlain
2020-05-18 19:25                   ` Johannes Berg
2020-05-18 19:59                     ` Luis Chamberlain
2020-05-18 20:07                       ` Johannes Berg
2020-05-18 21:18                         ` Luis Chamberlain
2020-05-18 20:28                     ` Jakub Kicinski
2020-05-18 20:29                       ` Johannes Berg
2020-05-18 20:35                         ` Jakub Kicinski
2020-05-18 20:41                           ` Johannes Berg
2020-05-18 20:46                             ` Jakub Kicinski
2020-05-18 21:22                               ` Luis Chamberlain
2020-05-18 22:16                                 ` Jakub Kicinski
2020-05-19  1:05                                   ` Luis Chamberlain
2020-05-19 21:15                                     ` [RFC 1/2] devlink: add simple fw crash helpers Jakub Kicinski
2020-05-22  5:20                                       ` Luis Chamberlain
2020-05-22 17:17                                         ` Jakub Kicinski
2020-05-22 20:46                                           ` Johannes Berg
2020-05-22 21:51                                             ` Luis Chamberlain
2020-05-22 23:23                                               ` Steve deRosier
2020-05-22 23:44                                                 ` Luis Chamberlain [this message]
2020-05-25  9:07                                                 ` Andy Shevchenko
2020-05-25 17:08                                                   ` Ben Greear
2020-05-25 20:57                                             ` Jakub Kicinski
2020-05-22 21:49                                           ` Luis Chamberlain
2020-05-19 21:15                                     ` [RFC 2/2] i2400m: use devlink health reporter Jakub Kicinski
2020-05-15 21:28 ` [PATCH v2 13/15] ath6kl: use new module_firmware_crashed() Luis Chamberlain
2020-05-16  4:12   ` Rafael Aquini
2020-05-15 21:28 ` [PATCH v2 14/15] brcm80211: " Luis Chamberlain
2020-05-16  4:13   ` Rafael Aquini
2020-05-15 21:28 ` [PATCH v2 15/15] mwl8k: " Luis Chamberlain
2020-05-16  4:13   ` Rafael Aquini

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