transport: Add blocking recv calls to uhd-dpdk

This adds an internal wait queue API to uhd-dpdk. Socket configuration
requests had their blocking calls re-implemented on top of this API, and
it is also used to service requests to wait on RX packets (w/ timeout).

The wait API involves a multi-producer, single-consumer queue per I/O
thread (waiter_ring), with a condition variable used for sleeping. The
data structure is shared between user thread and I/O thread, and because
timeouts make resource release time non-deterministic, we use reference
counting on the shared resource.

One reference is generated by the user thread and passed to the I/O
thread to consume. A user thread that still needs the data after waking
must get() another reference, to postpone the destruction of the
resource until it is done.

Timeouts are based on CLOCK_MONOTONIC. For recv, a timeout of 0
indicates blocking indefinitely, and a negative timeout indicates no
timeout is desired.

Also drop timeout for closing sockets in uhd-dpdk.
The timeout would allow a user thread to pre-empt the I/O thread's
cleanup process. The user thread would free data structures the I/O
thread still needed to function. Since this timeout is superfluous
anyway, let's just get rid of it.

Also add some more input checking and error reporting.

1 files changed, 14 insertions, 2 deletions

diff --git a/host/lib/include/uhd/transport/uhd-dpdk.h b/host/lib/include/uhd/transport/uhd-dpdk.h
index 68438fe40..8d46912bd 100644
--- a/host/lib/include/uhd/transport/uhd-dpdk.h
+++ b/host/lib/include/uhd/transport/uhd-dpdk.h
@@ -148,10 +148,11 @@ int uhd_dpdk_destroy(void);
  * @param sock pointer to socket
  * @param bufs pointer to array of buffers (to store buffer locations)
  * @param num_bufs number of buffers requested
+ * @param timeout Time (in us) to wait for a buffer
  *
  * @return Returns number of buffers retrieved or negative error code
  */
-int uhd_dpdk_request_tx_bufs(struct uhd_dpdk_socket *sock, struct rte_mbuf **bufs, unsigned int num_bufs);
+int uhd_dpdk_request_tx_bufs(struct uhd_dpdk_socket *sock, struct rte_mbuf **bufs, unsigned int num_bufs, int timeout);
 
 /**
  * Enqueues num_bufs buffers in sock TX buffer. Uses pointers to buffers in bufs table.
@@ -241,7 +242,18 @@ int uhd_dpdk_udp_get_info(struct uhd_dpdk_socket *sock, struct uhd_dpdk_sockarg_
  *
  * @return Return 0 for success, else failed
  */
-int uhd_dpdk_get_drop_count(struct uhd_dpdk_socket *sock, uint32_t *count);
+int uhd_dpdk_get_drop_count(struct uhd_dpdk_socket *sock, size_t *count);
+
+/**
+ * Get transferred packet count of provided socket
+ * Currently only tracks received packets (i.e. for RX)
+ *
+ * @param sock Socket to get information from
+ * @param count Pointer to location where information will be stored
+ *
+ * @return Return 0 for success, else failed
+ */
+int uhd_dpdk_get_xfer_count(struct uhd_dpdk_socket *sock, size_t *count);
 
 #ifdef __cplusplus
 }