[PATCH v3 3/8] eal/linux: fix closing of event FDs not owned by EAL

[Anatoly Burakov <anatoly.burakov@intel.com>]

rte_intr_efd_disable() decides whether to close the event FDs based on
max_intr being greater than nb_efd. This is a side effect of how
rte_intr_efd_enable() fills the handle for VFIO MSI-X, where an extra
slot is reserved for the misc interrupt, and only indirectly identifies
the eventfds that EAL created itself.

Any driver filling the event FD array for a VDEV or EXT handle and
setting max_intr the same way gets its descriptors closed by EAL even
though it owns them. The virtio-user driver does exactly this, so its
callfds are closed by rte_intr_efd_disable() and then closed again by
the driver on uninit.

Check the interrupt handle type instead, so that only the eventfds
created by rte_intr_efd_enable() for VFIO MSI-X are closed.

Fixes: b9e0662a931d ("eal/linux: add interrupt API for drivers")
Cc: stable@dpdk.org

Signed-off-by: Anatoly Burakov <anatoly.burakov@intel.com>
---
 lib/eal/linux/eal_interrupts.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/lib/eal/linux/eal_interrupts.c b/lib/eal/linux/eal_interrupts.c
index 4cfaeba7fe0..bdee1dd9777 100644
--- a/lib/eal/linux/eal_interrupts.c
+++ b/lib/eal/linux/eal_interrupts.c
@@ -1620,7 +1620,11 @@ rte_intr_efd_disable(struct rte_intr_handle *intr_handle)
 	uint32_t i;
 
 	rte_intr_free_epoll_fd(intr_handle);
-	if (rte_intr_max_intr_get(intr_handle) > rte_intr_nb_efd_get(intr_handle)) {
+	/* Only eventfds created by rte_intr_efd_enable() for MSI-X are owned
+	 * by the handle. In other modes the entries reference fds owned by
+	 * the device or the driver and must not be closed here.
+	 */
+	if (rte_intr_type_get(intr_handle) == RTE_INTR_HANDLE_VFIO_MSIX) {
 		for (i = 0; i < (uint32_t)rte_intr_nb_efd_get(intr_handle); i++)
 			close(rte_intr_efds_index_get(intr_handle, i));
 	}
-- 
2.52.0