Re: [PATCH v2] spi: qup: Add DMA capabilities

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



On Tue, Feb 24, 2015 at 03:00:03PM +0200, Stanimir Varbanov wrote:

> +static void spi_qup_dma_done(void *data)
> +{
> +	struct spi_qup *qup = data;
> +
> +	if (atomic_dec_and_test(&qup->dma_outstanding))
> +		complete(&qup->done);
> +}

I'm finding it hard to be thrilled about the use of atomics for
synchronization (they're just generally hard to work with) and...

> +	cookie = dmaengine_submit(desc);
> +	ret = dma_submit_error(cookie);
> +	if (ret)
> +		return ret;

> +	atomic_inc(&qup->dma_outstanding);

..don't we have two potential races here: one if somehow the DMA manages
to complete prior to the atomic_inc() (unlikely but that's what race
conditions are all about really) and one if we are issuing multiple DMAs
and the early ones complete before the later ones are issued?

Attachment: signature.asc
Description: Digital signature


[Index of Archives]     [Linux ARM Kernel]     [Linux ARM]     [Linux Omap]     [Fedora ARM]     [Linux for Sparc]     [IETF Annouce]     [Security]     [Bugtraq]     [Linux MIPS]     [ECOS]     [Asterisk Internet PBX]     [Linux API]

  Powered by Linux