linux-kernel - Re: [PATCH v4 06/14] cxl/region: Avoid duplicate call of cxl_find_decoder

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: <67c9ff24afcbb_1a772947f@dwillia2-xfh.jf.intel.com.notmuch>
Date: Thu, 6 Mar 2025 12:01:40 -0800
From: Dan Williams <dan.j.williams@...el.com>
To: Robert Richter <rrichter@....com>, Alison Schofield
	<alison.schofield@...el.com>, Vishal Verma <vishal.l.verma@...el.com>, "Ira
 Weiny" <ira.weiny@...el.com>, Dan Williams <dan.j.williams@...el.com>,
	Jonathan Cameron <Jonathan.Cameron@...wei.com>, Dave Jiang
	<dave.jiang@...el.com>, Davidlohr Bueso <dave@...olabs.net>
CC: <linux-cxl@...r.kernel.org>, <linux-kernel@...r.kernel.org>, Gregory Price
	<gourry@...rry.net>, "Fabio M. De Francesco"
	<fabio.m.de.francesco@...ux.intel.com>, Terry Bowman <terry.bowman@....com>,
	Robert Richter <rrichter@....com>
Subject: Re: [PATCH v4 06/14] cxl/region: Avoid duplicate call of
 cxl_find_decoder_early()

Robert Richter wrote:
> Function cxl_find_decoder_early() is called twice, in
> alloc_region_ref() and cxl_rr_alloc_decoder(). Both functions are
> subsequently called from cxl_port_attach_region(). Make the decoder a
> function argument to both which avoids a duplicate call of
> cxl_find_decoder_early().
> 
> Moving the call out of alloc_region_ref() also moves it out of the
> xa_for_each() loop in there. Now, cxld is determined no longer only
> for each auto-generated region, but now once for all regions
> regardless of auto-generated or not. This is fine as the cxld argument
> is needed for all regions in cxl_rr_alloc_decoder() and an error would
> be returned otherwise anyway. So it is better to determine the decoder
> in front of all this and fail early if missing instead of running
> through all that code with multiple calls of cxl_find_decoder_early().
> 
> Signed-off-by: Robert Richter <rrichter@....com>
> Reviewed-by: Gregory Price <gourry@...rry.net>
> Tested-by: Gregory Price <gourry@...rry.net>
> ---
>  drivers/cxl/core/region.c | 31 +++++++++++++++----------------
>  1 file changed, 15 insertions(+), 16 deletions(-)

The change of order makes some sense, but now none of the naming makes
any sense.

So, if you pickup the cxl_port_pick_region_decoder() rename, that
implies an allocation. Then it follows that cxl_rr_alloc_decoder()
should be renamed to something like cxl_rr_assign_decoder(), because the
"alloc" was what cxl_region_find_decoder() was doing in that function.

That also would imply that cxl_rr_assign_decoder() cannot fail if all
the allocation work is done ahead of time.