[PATCH v2] bus/pci: don't open uio device in secondary process

[Konrad Sztyber <konrad.sztyber@intel.com>]

The uio_pci_generic driver clears the bus master bit when the device
file is closed. So, when the secondary process terminates after probing
a device, that device becomes unusable in the primary process.

To avoid that, the device file is now opened only in the primary
process. The commit that introduced this regression, 847d78fb9530
("bus/pci: fix FD in secondary process"), only mentioned enabling access
to config space from secondary process, which still works, as it doesn't
rely on the device file.

Fixes: 847d78fb9530 ("bus/pci: fix FD in secondary process")
Cc: stable@dpdk.org

Signed-off-by: Konrad Sztyber <konrad.sztyber@intel.com>
---
 drivers/bus/pci/linux/pci_uio.c | 27 +++++++++++++++------------
 1 file changed, 15 insertions(+), 12 deletions(-)

diff --git a/drivers/bus/pci/linux/pci_uio.c b/drivers/bus/pci/linux/pci_uio.c
index 4c1d3327a9..5c4ba8098c 100644
--- a/drivers/bus/pci/linux/pci_uio.c
+++ b/drivers/bus/pci/linux/pci_uio.c
@@ -232,18 +232,6 @@ pci_uio_alloc_resource(struct rte_pci_device *dev,
 			loc->domain, loc->bus, loc->devid, loc->function);
 		return 1;
 	}
-	snprintf(devname, sizeof(devname), "/dev/uio%u", uio_num);
-
-	/* save fd */
-	fd = open(devname, O_RDWR);
-	if (fd < 0) {
-		PCI_LOG(ERR, "Cannot open %s: %s", devname, strerror(errno));
-		goto error;
-	}
-
-	if (rte_intr_fd_set(dev->intr_handle, fd))
-		goto error;
-
 	snprintf(cfgname, sizeof(cfgname),
 			"/sys/class/uio/uio%u/device/config", uio_num);
 
@@ -273,6 +261,21 @@ pci_uio_alloc_resource(struct rte_pci_device *dev,
 	if (rte_eal_process_type() != RTE_PROC_PRIMARY)
 		return 0;
 
+	/*
+	 * the uio_pci_generic driver clears the bus master enable bit when the device file is
+	 * closed, so open it only in the primary process
+	 */
+	snprintf(devname, sizeof(devname), "/dev/uio%u", uio_num);
+	/* save fd */
+	fd = open(devname, O_RDWR);
+	if (fd < 0) {
+		PCI_LOG(ERR, "Cannot open %s: %s", devname, strerror(errno));
+		goto error;
+	}
+
+	if (rte_intr_fd_set(dev->intr_handle, fd))
+		goto error;
+
 	/* allocate the mapping details for secondary processes*/
 	*uio_res = rte_zmalloc("UIO_RES", sizeof(**uio_res), 0);
 	if (*uio_res == NULL) {
-- 
2.45.0