linux-kernel - Re: [PATCH] kernel/resource: optimize find_next_iomem

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <783e9d9a-e408-c6f0-9a4b-050e1979b919@linux.intel.com>
Date: Mon, 3 Jun 2024 10:24:39 +0300 (EEST)
From: Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>
To: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
cc: Chia-I Wu <olvaffe@...il.com>, amd-gfx@...ts.freedesktop.org, 
    dri-devel@...ts.freedesktop.org, christian.koenig@....com, 
    alexander.deucher@....com, Greg Kroah-Hartman <gregkh@...uxfoundation.org>, 
    Alison Schofield <alison.schofield@...el.com>, 
    Dave Jiang <dave.jiang@...el.com>, Baoquan He <bhe@...hat.com>, 
    LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] kernel/resource: optimize find_next_iomem_res

On Sun, 2 Jun 2024, Andy Shevchenko wrote:

> On Fri, May 31, 2024 at 02:31:45PM -0700, Chia-I Wu wrote:
> > On Fri, May 31, 2024 at 1:57 AM Andy Shevchenko <
> > andriy.shevchenko@...ux.intel.com> wrote:
> > > On Thu, May 30, 2024 at 10:36:57PM -0700, Chia-I Wu wrote:
> 
> ...
> 
> > > P.S> I'm not so sure about this change. It needs a thoroughly testing, esp.
> > > in PCI case. Cc'ing to Ilpo.
> 
> > What's special about PCI?
> 
> PCI, due to its nature, may rebuild resources either by shrinking or expanding
> of the entire subtree after the PCI bridge in question. And this may happen at
> run-time due to hotplug support. But I'm not a deep expert in this area, Ilpo
> knows much more than me.

There is code which clearly tries to do expanding resource but that 
usually fails to work as intended because of a parent resource whose size 
is fixed because it's already assigned.

Some other code might block shrinking too under certain conditions.

This area would need to be reworked in PCI core but it's massive and 
scary looking change.

-- 
 i.