linux-kernel - Re: [PATCH] x86: adjust GFP mask handling for coherent allocations

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: <4AE6CA2A020000780001BF51@vpn.id2.novell.com>
Date:	Tue, 27 Oct 2009 09:23:38 +0000
From:	"Jan Beulich" <JBeulich@...ell.com>
To:	"FUJITA Tomonori" <fujita.tomonori@....ntt.co.jp>
Cc:	<mingo@...e.hu>, <yinghai@...nel.org>, <tglx@...utronix.de>,
	<tiwai@...e.de>, <linux-kernel@...r.kernel.org>,
	<jbarnes@...tuousgeek.org>, <hpa@...or.com>
Subject: Re: [PATCH] x86: adjust GFP mask handling for coherent
	 allocations

>>> FUJITA Tomonori <fujita.tomonori@....ntt.co.jp> 27.10.09 10:11 >>>
>If a driver doesn't want to GFP_DMA, it should set up the
>dma_coherent_mask of the device and pass it. In fact, it should do. A
>driver that uses the fallback device is broken.

Agreed.

>Why can't you fix drivers that use the fallback instead of adding
>another hack to the common place?

Because there's quite a few of them - just search for callers of
dma_alloc_coherent() passing NULL as the first argument. Of course
I'd rather see the fallback gone, but I think this requires cooperation
from/action taken by the driver maintainers first. A first step might be
to add a WRN_ON() for that case, but I don't see it being reasonable
to eliminate the fallback right away. Hence, with it having got broken
in .26 I think it is reasonable to fix it for the time being.

Jan

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/