[PATCH v2] pci: add O_CLOEXEC when open uio device

[PATCH v2] pci: add O_CLOEXEC when open uio device

[Weifeng Su]

In this scenario, the DPDK process invokes a script which
inherits an open file descriptor (FD) for a UIO device.
After the script execution is complete, the UIO device's
close operation is called. However, in a new kernel version
(865a11f987ab5f03:uio/uio_pci_generic: Disable bus-mastering on release),
this close operation causes the PCI bus master bit to be cleared,
rendering the device unusable and leading to unexpected behavior.

This modification was made to prevent the UIO device's FD
from being inherited by the child process.

Signed-off-by: Weifeng Su <suweifeng1@huawei.com>
---
 drivers/bus/pci/linux/pci_uio.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/bus/pci/linux/pci_uio.c b/drivers/bus/pci/linux/pci_uio.c
index d52125e49b..7ac142c36e 100644
--- a/drivers/bus/pci/linux/pci_uio.c
+++ b/drivers/bus/pci/linux/pci_uio.c
@@ -246,7 +246,7 @@ pci_uio_alloc_resource(struct rte_pci_device *dev,
 	snprintf(devname, sizeof(devname), "/dev/uio%u", uio_num);
 
 	/* save fd if in primary process */
-	fd = open(devname, O_RDWR);
+	fd = open(devname, O_RDWR | O_CLOEXEC);
 	if (fd < 0) {
 		RTE_LOG(ERR, EAL, "Cannot open %s: %s\n",
 			devname, strerror(errno));
-- 
2.18.0.windows.1

Re: [PATCH v2] pci: add O_CLOEXEC when open uio device

[Stephen Hemminger]

On Thu, 29 Jun 2023 10:53:39 +0800
Weifeng Su <suweifeng1@huawei.com> wrote:

> In this scenario, the DPDK process invokes a script which
> inherits an open file descriptor (FD) for a UIO device.
> After the script execution is complete, the UIO device's
> close operation is called. However, in a new kernel version
> (865a11f987ab5f03:uio/uio_pci_generic: Disable bus-mastering on release),
> this close operation causes the PCI bus master bit to be cleared,
> rendering the device unusable and leading to unexpected behavior.
> 
> This modification was made to prevent the UIO device's FD
> from being inherited by the child process.
> 
> Signed-off-by: Weifeng Su <suweifeng1@huawei.com>

Makes sense, the eventfd used form VFIO is already marked as close on exec.

Acked-by: Stephen Hamminger <stephen@networkplumber.org>