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, 3 insertions, 1 deletions

diff --git a/host/lib/transport/uhd-dpdk/CMakeLists.txt b/host/lib/transport/uhd-dpdk/CMakeLists.txt
index be683aaf2..0beb1eed5 100644
--- a/host/lib/transport/uhd-dpdk/CMakeLists.txt
+++ b/host/lib/transport/uhd-dpdk/CMakeLists.txt
@@ -22,13 +22,15 @@ if(ENABLE_DPDK)
         ${CMAKE_CURRENT_SOURCE_DIR}/uhd_dpdk_driver.c
         ${CMAKE_CURRENT_SOURCE_DIR}/uhd_dpdk_fops.c
         ${CMAKE_CURRENT_SOURCE_DIR}/uhd_dpdk_udp.c
+        ${CMAKE_CURRENT_SOURCE_DIR}/uhd_dpdk_wait.c
     )
     set_source_files_properties(
         ${CMAKE_CURRENT_SOURCE_DIR}/uhd_dpdk.c
         ${CMAKE_CURRENT_SOURCE_DIR}/uhd_dpdk_driver.c
         ${CMAKE_CURRENT_SOURCE_DIR}/uhd_dpdk_fops.c
         ${CMAKE_CURRENT_SOURCE_DIR}/uhd_dpdk_udp.c
-        PROPERTIES COMPILE_FLAGS ${UHD_DPDK_CFLAGS}
+        ${CMAKE_CURRENT_SOURCE_DIR}/uhd_dpdk_wait.c
+        PROPERTIES COMPILE_FLAGS "${UHD_DPDK_CFLAGS} -D_GNU_SOURCE"
     )
     include_directories(${DPDK_INCLUDE_DIR})
     LIBUHD_APPEND_LIBS(${DPDK_LIBRARIES})