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From: Kees Cook <keescook@chromium.org>
To: Petr Mladek <pmladek@suse.com>
Cc: Pavel Tatashin <pasha.tatashin@soleen.com>,
	Anton Vorontsov <anton@enomsg.org>,
	Colin Cross <ccross@android.com>, Tony Luck <tony.luck@intel.com>,
	Jonathan Corbet <corbet@lwn.net>,
	Benson Leung <bleung@chromium.org>,
	Rob Herring <robh+dt@kernel.org>,
	Michael Ellerman <mpe@ellerman.id.au>,
	Benjamin Herrenschmidt <benh@kernel.crashing.org>,
	Paul Mackerras <paulus@samba.org>,
	Enric Balletbo i Serra <enric.balletbo@collabora.com>,
	Sergey Senozhatsky <sergey.senozhatsky@gmail.com>,
	Steven Rostedt <rostedt@goodmis.org>,
	linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org,
	devicetree@vger.kernel.org, linuxppc-dev@lists.ozlabs.org
Subject: Re: [PATCH v4 2/6] printk: honor the max_reason field in kmsg_dumper
Date: Fri, 22 May 2020 10:34:17 -0700
Message-ID: <202005221032.859452DFA0@keescook> (raw)
In-Reply-To: <20200522165120.GL3464@linux-b0ei>

On Fri, May 22, 2020 at 06:51:20PM +0200, Petr Mladek wrote:
> On Fri 2020-05-15 11:44:30, Kees Cook wrote:
> > From: Pavel Tatashin <pasha.tatashin@soleen.com>
> > 
> > kmsg_dump() allows to dump kmesg buffer for various system events: oops,
> > panic, reboot, etc. It provides an interface to register a callback call
> > for clients, and in that callback interface there is a field "max_reason"
> > which gets ignored unless always_kmsg_dump is passed as kernel parameter.
> 
> Strictly speaking, this is not fully true. "max_reason" field is not
> ignored when set to KMSG_DUMP_PANIC even when always_kmsg_dump was not set.
> 
> It should be something like:
> 
> "which gets ignored for reason higher than KMSG_DUMP_OOPS unless
> always_kmsg_dump is passed as kernel parameter".
> 
> Heh, I wonder if anyone will be able to parse this ;-)

Ah yeah, good point. I've reworded things like this:


    kmsg_dump() allows to dump kmesg buffer for various system events: oops,
    panic, reboot, etc. It provides an interface to register a callback
    call for clients, and in that callback interface there is a field
    "max_reason", but it was getting ignored when set to any "reason"
    higher than KMSG_DUMP_OOPS unless "always_kmsg_dump" was passed as
    kernel parameter.

    Allow clients to actually control their "max_reason", and keep the
    current behavior when "max_reason" is not set.

> Otherwise, it looks good to me. With the updated commit message:
> 
> Reviewed-by: Petr Mladek <pmladek@suse.com>

Thanks!

-- 
Kees Cook

  reply index

Thread overview: 20+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-05-15 18:44 [PATCH v4 0/6] allow ramoops to collect all kmesg_dump events Kees Cook
2020-05-15 18:44 ` [PATCH v4 1/6] printk: Collapse shutdown types into a single dump reason Kees Cook
2020-05-15 19:17   ` Pavel Tatashin
2020-05-22 16:21   ` Petr Mladek
2020-05-23 11:16   ` Michael Ellerman
2020-05-15 18:44 ` [PATCH v4 2/6] printk: honor the max_reason field in kmsg_dumper Kees Cook
2020-05-22 16:51   ` Petr Mladek
2020-05-22 17:34     ` Kees Cook [this message]
2020-05-15 18:44 ` [PATCH v4 3/6] printk: Introduce kmsg_dump_reason_str() Kees Cook
2020-05-15 19:23   ` Pavel Tatashin
2020-05-15 18:44 ` [PATCH v4 4/6] pstore/platform: Pass max_reason to kmesg dump Kees Cook
2020-05-15 18:44 ` [PATCH v4 5/6] pstore/ram: Introduce max_reason and convert dump_oops Kees Cook
2020-05-15 19:30   ` Pavel Tatashin
2020-05-15 19:48     ` Kees Cook
2020-05-15 19:40   ` Pavel Tatashin
2020-05-15 19:53     ` Kees Cook
2020-05-15 18:44 ` [PATCH v4 6/6] ramoops: Add max_reason optional field to ramoops DT node Kees Cook
2020-05-18 22:45   ` Rob Herring
2020-05-18 23:04     ` Kees Cook
2020-05-15 19:13 ` [PATCH v4 0/6] allow ramoops to collect all kmesg_dump events Pavel Tatashin

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