[RFC 3/4] interrupts: mark file descriptors invalid on allocation

[David Marchand <david.marchand@redhat.com>]

Initialize fd, dev_fd, and all efds array elements as invalid in
rte_intr_instance_alloc().
This follows Unix convention, avoiding confusion with fd 0
which could result from zero-initialization.

Update the API documentation to reflect this behavior and add a
unit test check to verify the fd is invalid after allocation.

Remove now-redundant initialization calls that were setting the fd
invalid right after allocation.

Signed-off-by: David Marchand <david.marchand@redhat.com>
---
 app/test/test_interrupts.c             |  5 +++--
 doc/guides/rel_notes/release_26_11.rst |  5 +++++
 drivers/bus/cdx/cdx_vfio.c             |  6 ------
 drivers/bus/pci/linux/pci_vfio.c       | 11 -----------
 drivers/bus/pci/pci_common_uio.c       |  6 ------
 drivers/bus/vmbus/vmbus_common_uio.c   |  6 ------
 drivers/net/failsafe/failsafe.c        |  3 ---
 drivers/net/mana/mana.c                |  4 ----
 drivers/net/memif/rte_eth_memif.c      |  6 ------
 drivers/net/mlx4/mlx4.c                |  3 ---
 drivers/net/tap/rte_eth_tap.c          |  1 -
 lib/eal/common/eal_common_interrupts.c |  6 ++++++
 lib/eal/freebsd/eal_alarm.c            |  3 ---
 lib/eal/include/rte_interrupts.h       |  2 ++
 lib/eal/linux/eal_dev.c                |  4 ----
 15 files changed, 16 insertions(+), 55 deletions(-)

diff --git a/app/test/test_interrupts.c b/app/test/test_interrupts.c
index 3a5be92cd7..5901cec2fe 100644
--- a/app/test/test_interrupts.c
+++ b/app/test/test_interrupts.c
@@ -73,11 +73,12 @@ test_interrupt_init(void)
 			rte_intr_instance_alloc(RTE_INTR_INSTANCE_F_PRIVATE);
 		if (!intr_handles[i])
 			return -1;
+		/* Verify fd is initialized to -1 */
+		if (rte_intr_fd_get(intr_handles[i]) != -1)
+			return -1;
 	}
 
 	test_intr_handle = intr_handles[TEST_INTERRUPT_HANDLE_INVALID];
-	if (rte_intr_fd_set(test_intr_handle, -1))
-		return -1;
 	if (rte_intr_type_set(test_intr_handle, RTE_INTR_HANDLE_UNKNOWN))
 		return -1;
 
diff --git a/doc/guides/rel_notes/release_26_11.rst b/doc/guides/rel_notes/release_26_11.rst
index 938617ca75..55368b95a6 100644
--- a/doc/guides/rel_notes/release_26_11.rst
+++ b/doc/guides/rel_notes/release_26_11.rst
@@ -84,6 +84,11 @@ API Changes
    Also, make sure to start the actual text at the margin.
    =======================================================
 
+* interrupts: Updated interrupt handle file descriptor management.
+
+  * ``rte_intr_instance_alloc()`` now initializes file descriptors
+    to invalid values instead of zero.
+
 
 ABI Changes
 -----------
diff --git a/drivers/bus/cdx/cdx_vfio.c b/drivers/bus/cdx/cdx_vfio.c
index 11fe3265d2..0e4af4e940 100644
--- a/drivers/bus/cdx/cdx_vfio.c
+++ b/drivers/bus/cdx/cdx_vfio.c
@@ -397,9 +397,6 @@ cdx_vfio_map_resource_primary(struct rte_cdx_device *dev)
 	struct cdx_map *maps;
 	int vfio_dev_fd, i, ret;
 
-	if (rte_intr_fd_set(dev->intr_handle, -1))
-		return -1;
-
 	ret = rte_vfio_setup_device(RTE_CDX_BUS_DEVICES_PATH, dev_name,
 				    &vfio_dev_fd, &device_info);
 	if (ret)
@@ -493,9 +490,6 @@ cdx_vfio_map_resource_secondary(struct rte_cdx_device *dev)
 	const char *dev_name = dev->device.name;
 	struct cdx_map *maps;
 
-	if (rte_intr_fd_set(dev->intr_handle, -1))
-		return -1;
-
 	/* if we're in a secondary process, just find our tailq entry */
 	TAILQ_FOREACH(vfio_res, vfio_res_list, next) {
 		if (strcmp(vfio_res->name, dev_name))
diff --git a/drivers/bus/pci/linux/pci_vfio.c b/drivers/bus/pci/linux/pci_vfio.c
index bc5c5c2499..a92a0d86ec 100644
--- a/drivers/bus/pci/linux/pci_vfio.c
+++ b/drivers/bus/pci/linux/pci_vfio.c
@@ -742,12 +742,6 @@ pci_vfio_map_resource_primary(struct rte_pci_device *dev)
 
 	struct pci_map *maps;
 
-	if (rte_intr_fd_set(dev->intr_handle, -1))
-		return -1;
-
-	if (rte_intr_fd_set(dev->vfio_req_intr_handle, -1))
-		return -1;
-
 	/* store PCI address string */
 	snprintf(pci_addr, sizeof(pci_addr), PCI_PRI_FMT,
 			loc->domain, loc->bus, loc->devid, loc->function);
@@ -939,11 +933,6 @@ pci_vfio_map_resource_secondary(struct rte_pci_device *dev)
 
 	struct pci_map *maps;
 
-	if (rte_intr_fd_set(dev->intr_handle, -1))
-		return -1;
-	if (rte_intr_fd_set(dev->vfio_req_intr_handle, -1))
-		return -1;
-
 	/* store PCI address string */
 	snprintf(pci_addr, sizeof(pci_addr), PCI_PRI_FMT,
 			loc->domain, loc->bus, loc->devid, loc->function);
diff --git a/drivers/bus/pci/pci_common_uio.c b/drivers/bus/pci/pci_common_uio.c
index 71974e9f56..47d50721dc 100644
--- a/drivers/bus/pci/pci_common_uio.c
+++ b/drivers/bus/pci/pci_common_uio.c
@@ -101,12 +101,6 @@ pci_uio_map_resource(struct rte_pci_device *dev)
 	struct mapped_pci_res_list *uio_res_list =
 		RTE_TAILQ_CAST(rte_uio_tailq.head, mapped_pci_res_list);
 
-	if (rte_intr_fd_set(dev->intr_handle, -1))
-		return -1;
-
-	if (rte_intr_dev_fd_set(dev->intr_handle, -1))
-		return -1;
-
 	/* allocate uio resource */
 	ret = pci_uio_alloc_resource(dev, &uio_res);
 	if (ret)
diff --git a/drivers/bus/vmbus/vmbus_common_uio.c b/drivers/bus/vmbus/vmbus_common_uio.c
index c6e7e07302..7459f4ea7a 100644
--- a/drivers/bus/vmbus/vmbus_common_uio.c
+++ b/drivers/bus/vmbus/vmbus_common_uio.c
@@ -173,12 +173,6 @@ vmbus_uio_map_resource(struct rte_vmbus_device *dev)
 	int ret;
 
 	/* TODO: handle rescind */
-	if (rte_intr_fd_set(dev->intr_handle, -1))
-		return -1;
-
-	if (rte_intr_dev_fd_set(dev->intr_handle, -1))
-		return -1;
-
 	if (rte_intr_type_set(dev->intr_handle, RTE_INTR_HANDLE_UNKNOWN))
 		return -1;
 
diff --git a/drivers/net/failsafe/failsafe.c b/drivers/net/failsafe/failsafe.c
index aa3fe53b22..3ba143924d 100644
--- a/drivers/net/failsafe/failsafe.c
+++ b/drivers/net/failsafe/failsafe.c
@@ -279,9 +279,6 @@ fs_eth_dev_create(struct rte_vdev_device *vdev)
 		goto cancel_alarm;
 	}
 
-	if (rte_intr_fd_set(PRIV(dev)->intr_handle, -1))
-		goto cancel_alarm;
-
 	if (rte_intr_type_set(PRIV(dev)->intr_handle, RTE_INTR_HANDLE_EXT))
 		goto cancel_alarm;
 
diff --git a/drivers/net/mana/mana.c b/drivers/net/mana/mana.c
index 0b72f711a1..1864ba2a2b 100644
--- a/drivers/net/mana/mana.c
+++ b/drivers/net/mana/mana.c
@@ -1946,10 +1946,6 @@ mana_intr_install(struct rte_eth_dev *eth_dev, struct mana_priv *priv)
 		return -ENOMEM;
 	}
 
-	ret = rte_intr_fd_set(priv->intr_handle, -1);
-	if (ret)
-		goto free_intr;
-
 	ret = mana_fd_set_non_blocking(ctx->async_fd);
 	if (ret) {
 		DRV_LOG(ERR, "Failed to change async_fd to NONBLOCK");
diff --git a/drivers/net/memif/rte_eth_memif.c b/drivers/net/memif/rte_eth_memif.c
index 5d153c3a5a..04e12b8ffa 100644
--- a/drivers/net/memif/rte_eth_memif.c
+++ b/drivers/net/memif/rte_eth_memif.c
@@ -1496,9 +1496,6 @@ memif_tx_queue_setup(struct rte_eth_dev *dev,
 	mq->n_pkts = 0;
 	mq->n_bytes = 0;
 
-	if (rte_intr_fd_set(mq->intr_handle, -1))
-		return -rte_errno;
-
 	if (rte_intr_type_set(mq->intr_handle, RTE_INTR_HANDLE_EXT))
 		return -rte_errno;
 
@@ -1536,9 +1533,6 @@ memif_rx_queue_setup(struct rte_eth_dev *dev,
 	mq->n_pkts = 0;
 	mq->n_bytes = 0;
 
-	if (rte_intr_fd_set(mq->intr_handle, -1))
-		return -rte_errno;
-
 	if (rte_intr_type_set(mq->intr_handle, RTE_INTR_HANDLE_EXT))
 		return -rte_errno;
 
diff --git a/drivers/net/mlx4/mlx4.c b/drivers/net/mlx4/mlx4.c
index 28f1116891..dbcd98d49f 100644
--- a/drivers/net/mlx4/mlx4.c
+++ b/drivers/net/mlx4/mlx4.c
@@ -1062,9 +1062,6 @@ mlx4_pci_probe(struct rte_pci_driver *pci_drv, struct rte_pci_device *pci_dev)
 			goto port_error;
 		}
 
-		if (rte_intr_fd_set(priv->intr_handle, -1))
-			goto port_error;
-
 		if (rte_intr_type_set(priv->intr_handle, RTE_INTR_HANDLE_EXT))
 			goto port_error;
 
diff --git a/drivers/net/tap/rte_eth_tap.c b/drivers/net/tap/rte_eth_tap.c
index b93452f168..13114edba5 100644
--- a/drivers/net/tap/rte_eth_tap.c
+++ b/drivers/net/tap/rte_eth_tap.c
@@ -2191,7 +2191,6 @@ eth_dev_tap_create(struct rte_vdev_device *vdev, const char *tap_name,
 	dev->tx_pkt_burst = pmd_tx_burst;
 
 	rte_intr_type_set(pmd->intr_handle, RTE_INTR_HANDLE_EXT);
-	rte_intr_fd_set(pmd->intr_handle, -1);
 	dev->intr_handle = pmd->intr_handle;
 
 	/* Presetup the fds to -1 as being not valid */
diff --git a/lib/eal/common/eal_common_interrupts.c b/lib/eal/common/eal_common_interrupts.c
index a2a310750a..4e31a71319 100644
--- a/lib/eal/common/eal_common_interrupts.c
+++ b/lib/eal/common/eal_common_interrupts.c
@@ -68,6 +68,8 @@ struct rte_intr_handle *rte_intr_instance_alloc(uint32_t flags)
 		rte_errno = ENOMEM;
 		goto fail;
 	}
+	for (int i = 0; i < RTE_MAX_RXTX_INTR_VEC_ID; i++)
+		intr_handle->efds[i] = -1;
 
 	if (uses_rte_memory) {
 		intr_handle->elist = rte_zmalloc(NULL,
@@ -83,6 +85,8 @@ struct rte_intr_handle *rte_intr_instance_alloc(uint32_t flags)
 		goto fail;
 	}
 
+	intr_handle->fd = -1;
+	intr_handle->dev_fd = -1;
 	intr_handle->alloc_flags = flags;
 	intr_handle->nb_intr = RTE_MAX_RXTX_INTR_VEC_ID;
 
@@ -153,6 +157,8 @@ int rte_intr_event_list_update(struct rte_intr_handle *intr_handle, int size)
 		goto fail;
 	}
 	intr_handle->efds = tmp_efds;
+	for (int i = intr_handle->nb_intr; i < size; i++)
+		intr_handle->efds[i] = -1;
 
 	if (uses_rte_memory) {
 		tmp_elist = rte_realloc(intr_handle->elist,
diff --git a/lib/eal/freebsd/eal_alarm.c b/lib/eal/freebsd/eal_alarm.c
index c03e281e67..f7480d2802 100644
--- a/lib/eal/freebsd/eal_alarm.c
+++ b/lib/eal/freebsd/eal_alarm.c
@@ -73,9 +73,6 @@ rte_eal_alarm_init(void)
 	if (rte_intr_type_set(intr_handle, RTE_INTR_HANDLE_ALARM))
 		goto error;
 
-	if (rte_intr_fd_set(intr_handle, -1))
-		goto error;
-
 	/* on FreeBSD, timers don't use fd's, and their identifiers are stored
 	 * in separate namespace from fd's, so using any value is OK. however,
 	 * EAL interrupts handler expects fd's to be unique, so use an actual fd
diff --git a/lib/eal/include/rte_interrupts.h b/lib/eal/include/rte_interrupts.h
index 0ae16bbe19..1cfb9d3f8e 100644
--- a/lib/eal/include/rte_interrupts.h
+++ b/lib/eal/include/rte_interrupts.h
@@ -225,6 +225,8 @@ uint32_t rte_intr_active_events_flags(void);
  * can be realloced later based on size of MSIX interrupts supported by a PCI
  * device.
  *
+ * All file descriptors (fd, dev_fd, efds) are initialized to -1.
+ *
  * This function should be called from application or driver, before calling
  * any of the interrupt APIs.
  *
diff --git a/lib/eal/linux/eal_dev.c b/lib/eal/linux/eal_dev.c
index ec408649d0..c78e565427 100644
--- a/lib/eal/linux/eal_dev.c
+++ b/lib/eal/linux/eal_dev.c
@@ -326,10 +326,6 @@ rte_dev_event_monitor_start(void)
 	if (ret)
 		goto exit;
 
-	ret = rte_intr_fd_set(intr_handle, -1);
-	if (ret)
-		goto exit;
-
 	ret = dev_uev_socket_fd_create();
 	if (ret) {
 		EAL_LOG(ERR, "error create device event fd.");
-- 
2.54.0