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, 114 insertions, 0 deletions

diff --git a/host/lib/transport/uhd-dpdk/uhd_dpdk_wait.c b/host/lib/transport/uhd-dpdk/uhd_dpdk_wait.c
new file mode 100644
index 000000000..c00eaa3c4
--- /dev/null
+++ b/host/lib/transport/uhd-dpdk/uhd_dpdk_wait.c
@@ -0,0 +1,114 @@
+//
+// Copyright 2018 Ettus Research, a National Instruments Company
+//
+// SPDX-License-Identifier: GPL-3.0-or-later
+//
+#include "uhd_dpdk_wait.h"
+
+int _uhd_dpdk_waiter_wake(struct uhd_dpdk_wait_req *req,
+                          struct uhd_dpdk_thread *t)
+{
+    int stat = pthread_mutex_trylock(&req->mutex);
+    if (stat) {
+        if (rte_ring_full(t->waiter_ring)) {
+            RTE_LOG(ERR, USER2, "%s: Could not lock req mutex\n", __func__);
+            return -ENOBUFS;
+        } else {
+            req->reason = UHD_DPDK_WAIT_SIMPLE;
+            rte_ring_enqueue(t->waiter_ring, req);
+            return -EAGAIN;
+        }
+    }
+    stat = pthread_cond_signal(&req->cond);
+    if (stat)
+        RTE_LOG(ERR, USER2, "%s: Could not signal req cond\n", __func__);
+    pthread_mutex_unlock(&req->mutex);
+    uhd_dpdk_waiter_put(req);
+    return stat;
+}
+
+struct uhd_dpdk_wait_req *uhd_dpdk_waiter_alloc(enum uhd_dpdk_wait_type reason)
+{
+    struct uhd_dpdk_wait_req *req;
+    req = (struct uhd_dpdk_wait_req *) rte_zmalloc(NULL, sizeof(*req), 0);
+    if (!req)
+        return NULL;
+
+    pthread_mutex_init(&req->mutex, NULL);
+    pthread_condattr_t condattr;
+    pthread_condattr_init(&condattr);
+    pthread_condattr_setclock(&condattr, CLOCK_MONOTONIC);
+    pthread_cond_init(&req->cond, &condattr);
+    rte_atomic32_set(&req->refcnt, 1);
+    req->reason = reason;
+    return req;
+}
+
+static inline void uhd_dpdk_waiter_prepare(struct uhd_dpdk_wait_req *req)
+{
+    pthread_mutex_lock(&req->mutex);
+    /* Get a reference here, to be consumed by other thread (handshake) */
+    uhd_dpdk_waiter_get(req);
+}
+
+static inline int uhd_dpdk_waiter_submit(struct uhd_dpdk_wait_req *req,
+                                         int timeout)
+{
+    int retval = 0;
+    if (timeout < 0) {
+        retval = pthread_cond_wait(&req->cond, &req->mutex);
+    } else {
+        struct timespec timeout_spec;
+        clock_gettime(CLOCK_MONOTONIC, &timeout_spec);
+        timeout_spec.tv_sec += timeout/1000000;
+        timeout_spec.tv_nsec += (timeout % 1000000)*1000;
+        if (timeout_spec.tv_nsec > 1000000000) {
+            timeout_spec.tv_sec++;
+            timeout_spec.tv_nsec -= 1000000000;
+        }
+        retval = pthread_cond_timedwait(&req->cond, &req->mutex, &timeout_spec);
+    }
+    return retval;
+}
+
+int uhd_dpdk_waiter_wait(struct uhd_dpdk_wait_req *req, int timeout,
+                         struct uhd_dpdk_thread *t)
+{
+    int ret;
+    if (!req || !t)
+        return -EINVAL;
+
+    uhd_dpdk_waiter_prepare(req);
+
+    ret = rte_ring_enqueue(t->waiter_ring, req);
+    if (ret) {
+        uhd_dpdk_waiter_put(req);
+        pthread_mutex_unlock(&req->mutex);
+        return ret;
+    }
+
+    uhd_dpdk_waiter_submit(req, timeout);
+    pthread_mutex_unlock(&req->mutex);
+    return 0;
+}
+
+int uhd_dpdk_config_req_submit(struct uhd_dpdk_config_req *req,
+                               int timeout, struct uhd_dpdk_thread *t)
+{
+    int ret;
+    if (!req || !t)
+        return -EINVAL;
+
+    uhd_dpdk_waiter_prepare(req->waiter);
+
+    ret = rte_ring_enqueue(t->sock_req_ring, req);
+    if (ret) {
+        uhd_dpdk_waiter_put(req->waiter);
+        pthread_mutex_unlock(&req->waiter->mutex);
+        return ret;
+    }
+
+    uhd_dpdk_waiter_submit(req->waiter, timeout);
+    pthread_mutex_unlock(&req->waiter->mutex);
+    return 0;
+}