[dpdk-dev] [PATCH] vfio: correct system call error checking

[Neil Horman <nhorman@tuxdriver.com>]

Noticed today that ioctl error code return checking was incorrect in some of the
vfio code.  ioctl can return a negative value if the system detects an error
before the target device/driver can produce a return code.  The dpdk vfio code
only checks specfically for the values that it expects, which leaves it open to
accepting unexpected error codes as success.  For instance, if the vfio layer
noted that the iommu driver hadn't finished registering yet, it would return an
-EINVAL error code, but the dpdk would accept that as success, becuase it wasn't
0.

Fix this to specifically check for < 0 error codes

Signed-off-by: Neil Horman <nhorman@tuxdriver.com>
CC: Thomas Monjalon <thomas.monjalon@6wind.com>
---
 lib/librte_eal/linuxapp/eal/eal_pci_vfio.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/lib/librte_eal/linuxapp/eal/eal_pci_vfio.c b/lib/librte_eal/linuxapp/eal/eal_pci_vfio.c
index 4de6061..65aa8ad 100644
--- a/lib/librte_eal/linuxapp/eal/eal_pci_vfio.c
+++ b/lib/librte_eal/linuxapp/eal/eal_pci_vfio.c
@@ -319,16 +319,16 @@ pci_vfio_get_container_fd(void)
 
 		/* check VFIO API version */
 		ret = ioctl(vfio_container_fd, VFIO_GET_API_VERSION);
-		if (ret != VFIO_API_VERSION) {
-			RTE_LOG(ERR, EAL, "  unknown VFIO API version!\n");
+		if ((ret < 0) || (ret != VFIO_API_VERSION)) {
+			RTE_LOG(ERR, EAL, "  unknown VFIO API version! errno = %d\n", errno);
 			close(vfio_container_fd);
 			return -1;
 		}
 
 		/* check if we support IOMMU type 1 */
 		ret = ioctl(vfio_container_fd, VFIO_CHECK_EXTENSION, VFIO_TYPE1_IOMMU);
-		if (!ret) {
-			RTE_LOG(ERR, EAL, "  unknown IOMMU driver!\n");
+		if (ret <= 0) {
+			RTE_LOG(ERR, EAL, "  unknown IOMMU driver! errno = %d\n", errno);
 			close(vfio_container_fd);
 			return -1;
 		}
-- 
1.8.3.1