[dpdk-dev] [PATCH v4] net/tap: add Rx interrupts

[Moti Haimovsky]

This patch adds support for registering and waiting for Rx interrupts.
This allows applications to wait for Rx events from the PMD using the
DPDK rte_epoll subsystem.

Signed-off-by: Moti Haimovsky <motih at mellanox.com>
---
V4:
Modified license in tap_intr.c to SPDX-License.

V3:
Fixed coding style warnings.

V2:
Modifications according to inputs from Pascal Mazon
* Removed unneeded counter limit check.
---
 doc/guides/nics/features/tap.ini |   1 +
 drivers/net/tap/Makefile         |   1 +
 drivers/net/tap/rte_eth_tap.c    |  17 +++++-
 drivers/net/tap/rte_eth_tap.h    |   4 ++
 drivers/net/tap/tap_intr.c       | 110 +++++++++++++++++++++++++++++++++++++++
 5 files changed, 132 insertions(+), 1 deletion(-)
 create mode 100644 drivers/net/tap/tap_intr.c

diff --git a/doc/guides/nics/features/tap.ini b/doc/guides/nics/features/tap.ini
index f0e893d..8bc5187 100644
--- a/doc/guides/nics/features/tap.ini
+++ b/doc/guides/nics/features/tap.ini
@@ -7,6 +7,7 @@
 Speed capabilities   = P
 Link status          = Y
 Link status event    = Y
+Rx interrupt         = Y
 Jumbo frame          = Y
 Promiscuous mode     = Y
 Allmulticast mode    = Y
diff --git a/drivers/net/tap/Makefile b/drivers/net/tap/Makefile
index 315c6bd..ccc5c5f 100644
--- a/drivers/net/tap/Makefile
+++ b/drivers/net/tap/Makefile
@@ -36,6 +36,7 @@ SRCS-$(CONFIG_RTE_LIBRTE_PMD_TAP) += tap_flow.c
 SRCS-$(CONFIG_RTE_LIBRTE_PMD_TAP) += tap_netlink.c
 SRCS-$(CONFIG_RTE_LIBRTE_PMD_TAP) += tap_tcmsgs.c
 SRCS-$(CONFIG_RTE_LIBRTE_PMD_TAP) += tap_bpf_api.c
+SRCS-$(CONFIG_RTE_LIBRTE_PMD_TAP) += tap_intr.c
 
 include $(RTE_SDK)/mk/rte.lib.mk
 
diff --git a/drivers/net/tap/rte_eth_tap.c b/drivers/net/tap/rte_eth_tap.c
index fd42572..29d6356 100644
--- a/drivers/net/tap/rte_eth_tap.c
+++ b/drivers/net/tap/rte_eth_tap.c
@@ -1218,7 +1218,7 @@ enum ioctl_mode {
 }
 
 static int
-tap_intr_handle_set(struct rte_eth_dev *dev, int set)
+tap_lsc_intr_handle_set(struct rte_eth_dev *dev, int set)
 {
 	struct pmd_internals *pmd = dev->data->dev_private;
 
@@ -1243,6 +1243,20 @@ enum ioctl_mode {
 					    tap_dev_intr_handler, dev);
 }
 
+static int
+tap_intr_handle_set(struct rte_eth_dev *dev, int set)
+{
+	int err;
+
+	err = tap_lsc_intr_handle_set(dev, set);
+	if (err)
+		return err;
+	err = tap_rx_intr_vec_set(dev, set);
+	if (err && set)
+		tap_lsc_intr_handle_set(dev, 0);
+	return err;
+}
+
 static const uint32_t*
 tap_dev_supported_ptypes_get(struct rte_eth_dev *dev __rte_unused)
 {
@@ -1375,6 +1389,7 @@ enum ioctl_mode {
 
 	pmd->intr_handle.type = RTE_INTR_HANDLE_EXT;
 	pmd->intr_handle.fd = -1;
+	dev->intr_handle = &pmd->intr_handle;
 
 	/* Presetup the fds to -1 as being not valid */
 	for (i = 0; i < RTE_PMD_TAP_MAX_QUEUES; i++) {
diff --git a/drivers/net/tap/rte_eth_tap.h b/drivers/net/tap/rte_eth_tap.h
index d4f1e6c..ed85244 100644
--- a/drivers/net/tap/rte_eth_tap.h
+++ b/drivers/net/tap/rte_eth_tap.h
@@ -106,4 +106,8 @@ struct pmd_internals {
 	struct rte_intr_handle intr_handle;          /* LSC interrupt handle. */
 };
 
+/* tap_intr.c */
+
+int tap_rx_intr_vec_set(struct rte_eth_dev *dev, int set);
+
 #endif /* _RTE_ETH_TAP_H_ */
diff --git a/drivers/net/tap/tap_intr.c b/drivers/net/tap/tap_intr.c
new file mode 100644
index 0000000..b0e1991
--- /dev/null
+++ b/drivers/net/tap/tap_intr.c
@@ -0,0 +1,110 @@
+/* SPDX-License-Identifier: BSD-3-Clause
+ * Copyright 2018 Mellanox Technologies, Ltd.
+ */
+
+/**
+ * @file
+ * Interrupts handling for tap driver.
+ */
+
+#include <assert.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <signal.h>
+#include <stdint.h>
+#include <stdlib.h>
+#include <unistd.h>
+
+#include <rte_eth_tap.h>
+#include <rte_errno.h>
+#include <rte_interrupts.h>
+
+
+/**
+ * Unregister Rx interrupts free the queue interrupt vector.
+ *
+ * @param dev
+ *   Pointer to the tap rte_eth_dev structure.
+ */
+static void
+tap_rx_intr_vec_uninstall(struct rte_eth_dev *dev)
+{
+	struct pmd_internals *pmd = dev->data->dev_private;
+	struct rte_intr_handle *intr_handle = &pmd->intr_handle;
+
+	rte_intr_free_epoll_fd(intr_handle);
+	free(intr_handle->intr_vec);
+	intr_handle->intr_vec = NULL;
+	intr_handle->nb_efd = 0;
+}
+
+/**
+ * Allocate Rx queue interrupt vector and register Rx interrupts.
+ *
+ * @param dev
+ *   Pointer to the tap rte_eth_dev device structure.
+ *
+ * @return
+ *   0 on success, negative errno value otherwise and rte_errno is set.
+ */
+static int
+tap_rx_intr_vec_install(struct rte_eth_dev *dev)
+{
+	struct pmd_internals *pmd = dev->data->dev_private;
+	unsigned int rxqs_n = pmd->dev->data->nb_rx_queues;
+	struct rte_intr_handle *intr_handle = &pmd->intr_handle;
+	unsigned int n = RTE_MIN(rxqs_n, (uint32_t)RTE_MAX_RXTX_INTR_VEC_ID);
+	unsigned int i;
+	unsigned int count = 0;
+
+	if (!dev->data->dev_conf.intr_conf.rxq)
+		return 0;
+	intr_handle->intr_vec = malloc(sizeof(intr_handle->intr_vec[rxqs_n]));
+	if (intr_handle->intr_vec == NULL) {
+		rte_errno = ENOMEM;
+		RTE_LOG(ERR, PMD,
+			"failed to allocate memory for interrupt vector,"
+			" Rx interrupts will not be supported");
+		return -rte_errno;
+	}
+	for (i = 0; i < n; i++) {
+		struct rx_queue *rxq = pmd->dev->data->rx_queues[i];
+
+		/* Skip queues that cannot request interrupts. */
+		if (!rxq || rxq->fd <= 0) {
+			/* Use invalid intr_vec[] index to disable entry. */
+			intr_handle->intr_vec[i] =
+				RTE_INTR_VEC_RXTX_OFFSET +
+				RTE_MAX_RXTX_INTR_VEC_ID;
+			continue;
+		}
+		intr_handle->intr_vec[i] = RTE_INTR_VEC_RXTX_OFFSET + count;
+		intr_handle->efds[count] = rxq->fd;
+		count++;
+	}
+	if (!count)
+		tap_rx_intr_vec_uninstall(dev);
+	else
+		intr_handle->nb_efd = count;
+	return 0;
+}
+
+/**
+ * Register or unregister the Rx interrupts.
+ *
+ * @param dev
+ *   Pointer to the tap rte_eth_dev device structure.
+ * @param set
+ *   should the operation be register or unregister the interrupts.
+ *
+ * @return
+ *   0 on success, negative errno value otherwise and rte_errno is set.
+ */
+int
+tap_rx_intr_vec_set(struct rte_eth_dev *dev, int set)
+{
+	tap_rx_intr_vec_uninstall(dev);
+	if (set)
+		return tap_rx_intr_vec_install(dev);
+	return 0;
+}
-- 
1.8.3.1