[dpdk-dev] [PATCH v5] dmadev: introduce DMA device library

[Bruce Richardson]

On Fri, Jul 16, 2021 at 10:45:35AM +0800, Chengwen Feng wrote:
> This patch introduce 'dmadevice' which is a generic type of DMA
> device.
> 
> The APIs of dmadev library exposes some generic operations which can
> enable configuration and I/O with the DMA devices.
> 
> Signed-off-by: Chengwen Feng <fengchengwen at huawei.com>
> ---
<snip>
> +
> +static struct rte_dmadev *
> +dmadev_allocate(const char *name)
> +{
> +	struct rte_dmadev *dev;
> +	uint16_t dev_id;
> +
> +	dev = dmadev_find(name);
> +	if (dev != NULL) {
> +		RTE_DMADEV_LOG(ERR, "DMA device already allocated\n");
> +		return NULL;
> +	}
> +
> +	dev_id = dmadev_find_free_dev();
> +	if (dev_id == RTE_DMADEV_MAX_DEVS) {
> +		RTE_DMADEV_LOG(ERR, "Reached maximum number of DMA devices\n");
> +		return NULL;
> +	}
> +
> +	if (dmadev_shared_data_prepare() != 0) {
> +		RTE_DMADEV_LOG(ERR, "Cannot allocate DMA shared data\n");
> +		return NULL;
> +	}
> +
The order of the "shared_data_prepare" and "find_free_dev" calls needs to
be reversed. When calling allocate for the first dmadev driver you will get
a segfault in find function, since it accesses the shared data which has
not been created yet.

Regards,
/Bruce