linux-kernel - Re: [PATCH V2 2/2] dmaengine: tegra-adma: Add support for Tegra210 ADMA

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: <16524792.BmEijCQ1oc@wuerfel>
Date:	Tue, 06 Oct 2015 11:32:35 +0200
From:	Arnd Bergmann <arnd@...db.de>
To:	Jon Hunter <jonathanh@...dia.com>
Cc:	Laxman Dewangan <ldewangan@...dia.com>,
	Vinod Koul <vinod.koul@...el.com>,
	Stephen Warren <swarren@...dotorg.org>,
	Thierry Reding <thierry.reding@...il.com>,
	Alexandre Courbot <gnurou@...il.com>,
	Rob Herring <robh+dt@...nel.org>,
	Pawel Moll <pawel.moll@....com>,
	Mark Rutland <mark.rutland@....com>,
	Ian Campbell <ijc+devicetree@...lion.org.uk>,
	Kumar Gala <galak@...eaurora.org>, dmaengine@...r.kernel.org,
	linux-tegra@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH V2 2/2] dmaengine: tegra-adma: Add support for Tegra210 ADMA

On Monday 05 October 2015 13:10:07 Jon Hunter wrote:
> Add support for the Tegra210 Audio DMA controller that is used for
> transferring data between system memory and the Audio sub-system.
> The driver only supports cyclic transfers because this is being solely
> used for audio.
> 
> This driver is based upon the work by Dara Ramesh <dramesh@...dia.com>.
> 
> Signed-off-by: Jon Hunter <jonathanh@...dia.com>

This version looks much better!

Just one small comment:

> +	slave_req = dma_spec->args[0];
> +	slave_dir = dma_spec->args[1];
> +
> +	if (slave_req == 0)
> +		return NULL;
> +
> +	switch (slave_dir) {
> +	case ADMA_AHUB_TO_MEM:
> +		if (slave_req > tdma->rx_requests)
> +			return NULL;
> +
> +		if (tdma->rx_requests_reserved & BIT(slave_req))
> +			return NULL;
> +
> +		tdma->rx_requests_reserved |= BIT(slave_req);
> +		break;

The rx_requests_reserved logic looks racy, if you have more than
one concurrent request or release. Better use atomic_test_and_set()
here and turn the variable into an atomic_t.

	Arbd
--
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/