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 <redacted>
---

<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