LKML Archive on lore.kernel.org
 help / color / Atom feed
From: Pavel Tatashin <pasha.tatashin@soleen.com>
To: Petr Mladek <pmladek@suse.com>
Cc: Kees Cook <keescook@chromium.org>,
	Anton Vorontsov <anton@enomsg.org>,
	Colin Cross <ccross@android.com>, Tony Luck <tony.luck@intel.com>,
	Jonathan Corbet <corbet@lwn.net>,
	Rob Herring <robh+dt@kernel.org>,
	Benson Leung <bleung@chromium.org>,
	Enric Balletbo i Serra <enric.balletbo@collabora.com>,
	Sergey Senozhatsky <sergey.senozhatsky@gmail.com>,
	Steven Rostedt <rostedt@goodmis.org>,
	James Morris <jmorris@namei.org>, Sasha Levin <sashal@kernel.org>,
	Linux Doc Mailing List <linux-doc@vger.kernel.org>,
	LKML <linux-kernel@vger.kernel.org>,
	devicetree@vger.kernel.org
Subject: Re: [PATCH v3 0/6] allow ramoops to collect all kmesg_dump events
Date: Tue, 12 May 2020 10:03:44 -0400
Message-ID: <CA+CK2bBMUxxuTBicQ7ihKpN3jK94mMjcNCXhnAXUaODce09Wmw@mail.gmail.com> (raw)
In-Reply-To: <20200512131655.GE17734@linux-b0ei>

Hi Petr,

> Alternative solution is to dump all messages using ramoops. The
> problem is that it currently works only during Oops and panic
> situation. This is solved by this patchset.
>
>
> OK, I personally see this as two separate problems:
>
>    1. Missing support to set loglevel per console.
>    2. Missing support to dump messages for other reasons.
>
> I would remove the paragraph about console log levels completely.

OK, I see your point, this paragraph can be removed, however, I think
it makes it clear to understand the rationale for this change. As I
understand, the per console loglevel has been proposed but were never
accepted.

> It is your reason to use ramoops. But it is not reason to modify
> the logic about max_reason.
>
>
> Now, the max_reason logic makes sense only when all the values
> have some ordering. Is this the case?
>
> I see it as two distinct sets:
>
>    + panic, oops, emerg: describe how critical is an error situation
>    + restart, halt, poweroff: describe behavior when the system goes down
>
> Let's say that panic is more critical than oops. Is restart more
> critical than halt?
>
> If you want the dump during restart. Does it mean that you want it
> also during emergency situation?
>
> My fear is that this patchset is going to introduce user interface
> (max_reason) with a weird logic. IMHO, max_reason is confusing even
> in the code and we should not spread this to users.
>
> Is there any reason why the existing printk.always_kmsg_dump option
> is not enough for you?

printk.always_kmsg_dump is not working for me because ramoops has its
own filtering based on dump_oops boolean, and ignores everything but
panics and conditionally oops.
max_reason makes the ramoops internal logic cleaner compared to using dump_oops.

I agree, the reasons in kmsg_dump_reason do not order well  (I
actually want to add another reason for kexec type reboots, and where
do I put it?), so how about if we change the ordering list to
bitfield/flags, and instead of max_reason provide: "reasons" bitset?

Thank you,
Pasha

  reply index

Thread overview: 26+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-05-06 21:15 Kees Cook
2020-05-06 21:15 ` [PATCH v3 1/6] printk: honor the max_reason field in kmsg_dumper Kees Cook
2020-05-06 21:15 ` [PATCH v3 2/6] pstore/platform: Pass max_reason to kmesg dump Kees Cook
2020-05-06 21:25   ` Joe Perches
2020-05-06 22:40     ` Kees Cook
2020-05-06 21:15 ` [PATCH v3 3/6] pstore/ram: Refactor DT size parsing Kees Cook
2020-05-07 12:57   ` Pavel Tatashin
2020-05-07 18:04     ` Kees Cook
2020-05-06 21:15 ` [PATCH v3 4/6] pstore/ram: Introduce max_reason and convert dump_oops Kees Cook
2020-05-06 21:17   ` Kees Cook
2020-05-12 23:35   ` Tyler Hicks
2020-05-12 23:57     ` Kees Cook
2020-05-16  2:43     ` Kees Cook
2020-05-06 21:15 ` [PATCH v3 5/6] ramoops: Add max_reason optional field to ramoops DT node Kees Cook
2020-05-06 21:15 ` [PATCH v3 6/6] pstore/ram: Adjust module param permissions to reflect reality Kees Cook
2020-05-12 13:16 ` [PATCH v3 0/6] allow ramoops to collect all kmesg_dump events Petr Mladek
2020-05-12 14:03   ` Pavel Tatashin [this message]
2020-05-12 15:52     ` Petr Mladek
2020-05-12 16:03       ` Steven Rostedt
2020-05-12 16:49       ` Pavel Tatashin
2020-05-12 18:53         ` Kees Cook
2020-05-12 18:45       ` Kees Cook
2020-05-13  7:34         ` Petr Mladek
2020-05-13  7:47           ` Kees Cook
2020-05-13 14:35             ` Pavel Tatashin
2020-05-13 20:15               ` Kees Cook

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=CA+CK2bBMUxxuTBicQ7ihKpN3jK94mMjcNCXhnAXUaODce09Wmw@mail.gmail.com \
    --to=pasha.tatashin@soleen.com \
    --cc=anton@enomsg.org \
    --cc=bleung@chromium.org \
    --cc=ccross@android.com \
    --cc=corbet@lwn.net \
    --cc=devicetree@vger.kernel.org \
    --cc=enric.balletbo@collabora.com \
    --cc=jmorris@namei.org \
    --cc=keescook@chromium.org \
    --cc=linux-doc@vger.kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=pmladek@suse.com \
    --cc=robh+dt@kernel.org \
    --cc=rostedt@goodmis.org \
    --cc=sashal@kernel.org \
    --cc=sergey.senozhatsky@gmail.com \
    --cc=tony.luck@intel.com \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

LKML Archive on lore.kernel.org

Archives are clonable:
	git clone --mirror https://lore.kernel.org/lkml/0 lkml/git/0.git
	git clone --mirror https://lore.kernel.org/lkml/1 lkml/git/1.git
	git clone --mirror https://lore.kernel.org/lkml/2 lkml/git/2.git
	git clone --mirror https://lore.kernel.org/lkml/3 lkml/git/3.git
	git clone --mirror https://lore.kernel.org/lkml/4 lkml/git/4.git
	git clone --mirror https://lore.kernel.org/lkml/5 lkml/git/5.git
	git clone --mirror https://lore.kernel.org/lkml/6 lkml/git/6.git
	git clone --mirror https://lore.kernel.org/lkml/7 lkml/git/7.git
	git clone --mirror https://lore.kernel.org/lkml/8 lkml/git/8.git
	git clone --mirror https://lore.kernel.org/lkml/9 lkml/git/9.git

	# If you have public-inbox 1.1+ installed, you may
	# initialize and index your mirror using the following commands:
	public-inbox-init -V2 lkml lkml/ https://lore.kernel.org/lkml \
		linux-kernel@vger.kernel.org
	public-inbox-index lkml

Example config snippet for mirrors

Newsgroup available over NNTP:
	nntp://nntp.lore.kernel.org/org.kernel.vger.linux-kernel


AGPL code for this site: git clone https://public-inbox.org/public-inbox.git