From mboxrd@z Thu Jan 1 00:00:00 1970 From: Petr Mladek Subject: Re: [PATCH 19/30] panic: Add the panic hypervisor notifier list Date: Thu, 19 May 2022 09:03:52 +0200 Message-ID: References: <20220427224924.592546-1-gpiccoli@igalia.com> <20220427224924.592546-20-gpiccoli@igalia.com> Mime-Version: 1.0 Return-path: DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1652943838; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=395st/CngVntAAOn5uSBsdHcf6UJsehUQOcbe6ab9wI=; b=qJ/FgyV3p4LuXUdkZjoAbs2+ewn4o7aNZN0S67D2rC96Mde70WoKxt5D1iYy3vIxFGNywX NYQFStO7xXozlUSKqQPZCblT/M2McgEFa5ttVGDSrZzFsBjH4DUBLxqHsrlOhubnXz8Ip9 VRfQAfc3f6HDJx77hS/XQSQpNXuMeJQ= Content-Disposition: inline In-Reply-To: List-ID: Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: "Guilherme G. Piccoli" Cc: David Gow , Evan Green , Julius Werner , Scott Branden , bcm-kernel-feedback-list@broadcom.com, Sebastian Reichel , linux-pm@vger.kernel.org, Florian Fainelli , akpm@linux-foundation.org, bhe@redhat.com, kexec@lists.infradead.org, linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-alpha@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-edac@vger.kernel.org, linux-hyperv@vger.kernel.org, linux-leds@vger.kernel.org, linux-mips@vger.kernel.org, linux-parisc@vger.kernel.org, linux-remoteproc@vger.kernel.org, linux-s390@vger.kernel.org, linux-tegra@vger.kernel.org, linux-um@lists.infradead.org, linux-xtensa@linux-xtensa.org On Wed 2022-05-18 10:16:20, Guilherme G. Piccoli wrote: > On 18/05/2022 04:58, Petr Mladek wrote: > > [...] > >> I does similar things like kmsg_dump() so it should be called in > >> the same location (after info notifier list and before kdump). > >> > >> A solution might be to put it at these notifiers at the very > >> end of the "info" list or make extra "dump" notifier list. > > > > I just want to point out that the above idea has problems. > > Notifiers storing kernel log need to be treated as kmsg_dump(). > > In particular, we would need to know if there are any. > > We do not need to call "info" notifier list before kdump > > when there is no kernel log dumper registered. > > > > Notifiers respect the priority concept, which is just a number that > orders the list addition (and the list is called in order). > > I've used the last position to panic_print() [in patch 25] - one idea > here is to "reserve" the last position (represented by INT_MIN) for > notifiers that act like kmsg_dump(). I couldn't find any IIRC, but that > doesn't prevent us to save this position and comment about that. I would ignore it for now. If anyone would want to safe the log then they would need to read it. They will most likely use the existing kmsg_dump() infastructure. In fact, they should use it to avoid a code duplication. Best Regards, Petr