Re: [PATCH v2] ARM/dma-mapping: use kvcalloc for fallback memory allocation need

From: Deepak R Varma <drv@mailo.com>
To: "Russell King (Oracle)" <linux@armlinux.org.uk>
Cc: linux-arm-kernel@lists.infradead.org,
	linux-kernel@vger.kernel.org,
	Praveen Kumar <kumarpraveen@linux.microsoft.com>,
	Saurabh Singh Sengar <ssengar@microsoft.com>,
	Julia Lawall <julia.lawall@inria.fr>,
	Deepak R Varma <drv@mailo.com>
Subject: Re: [PATCH v2] ARM/dma-mapping: use kvcalloc for fallback memory allocation need
Date: Tue, 3 Jan 2023 16:18:57 +0530	[thread overview]
Message-ID: <Y7QIGfF3GyD5nsP3@qemulion> (raw)
In-Reply-To: <Y7QBKMzuzNQAdKyY@shell.armlinux.org.uk>

On Tue, Jan 03, 2023 at 10:19:20AM +0000, Russell King (Oracle) wrote:
> On Wed, Dec 28, 2022 at 03:49:44PM +0530, Deepak R Varma wrote:
> > On Tue, Dec 20, 2022 at 07:46:32PM +0530, Deepak R Varma wrote:
> > > Current conditional determination of whether to use kzalloc or vzalloc
> > > has known issues such as "indefinite retry" when less than PAGE_SIZE
> > > memory is needed, but is unavailable. This LWN article [1] describes
> > > these issues in greater detail. Use helper function kvcalloc() instead
> > > which is more efficient in terms of performance and security.
> > >
> > >  	[1] https://lwn.net/Articles/711653/
> > >
> > > This patch proposal is based on following Coccinelle warning using the
> > > kvmalloc.cocci semantic patch.
> > > 	arch/arm/mm/dma-mapping.c:858:28-29: WARNING opportunity for kvmalloc
> > >
> > > The semantic patch suggests using kvzalloc() helper function, however,
> > > this patch proposes to use kvcalloc instead. kvcalloc() helper function
> > > uses 2-factor argument form which is better from a security perspective
> > > as described in the following KSPP project commit.
> > >
> > > 	Commit 4e3fd7217105 ("wireguard: ratelimiter: use kvcalloc() instead of kvzalloc()")
> > >
> > > Signed-off-by: Deepak R Varma <drv@mailo.com>
> >
> > Hello,
> > May I please request a review and feedback on this patch proposal?
>
> The DMA API on ARM has been maintained by others recently, so it's no
> longer up to me. Please include Christoph Hellwig <hch@lst.de> when
> sending changes for this. Thanks.

Sure. Actually the get_maintainer.pl scripts still returns yourself as the
maintainer for this driver. Hence the email to you.
I will send a v3 and include the change you asked for. I will keep you in cc if
you don't mind.

Also, let me know if I can help with getting the maintainer list updated for
this core subsystem.

Thank you,
./drv

>
> --
> RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
> FTTP is here! 40Mbps down 10Mbps up. Decent connectivity at last!

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