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?
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