Re: [libvirt] [PATCH v2 9/9] Wait for iommmu device to go away before reprobing the host driver

There could be a delay of 1 or 2 seconds before the vfio-pci driver is unbound and the device file /dev/vfio/<iommu> is actually removed. If the file exists, the host driver probing the device can lead to crash. So, wait and avoid the crash. Signed-off-by: Shivaprasad G Bhat <sbhat(a)linux.vnet.ibm.com&gt; --- src/util/virpci.c | 42 ++++++++++++++++++++++++++++++++++++++++++ tests/virpcimock.c | 14 ++++++++++++-- 2 files changed, 54 insertions(+), 2 deletions(-) diff --git a/src/util/virpci.c b/src/util/virpci.c index 0bb465b..68fd54c 100644 --- a/src/util/virpci.c +++ b/src/util/virpci.c @@ -1098,6 +1098,43 @@ virPCIIsAKnownStub(char *driver) return ret; } +#define VFIO_UNBIND_TIMEOUT 10 + +/* It is not safe to initiate host driver probe if the vfio driver has not + * completely unbound the device. Usual wait time is 1 to 2 seconds. + * So, return if the unbind didn't complete in 10 seconds. + */ +static int +virPCIWaitForVFIOUnbindCompletion(virPCIDevicePtr dev) +{ + int retry = 0; + int ret = -1; + char *path = NULL; + + if (!(path = virPCIDeviceGetIOMMUGroupDev(dev))) + goto cleanup; + + while (retry++ < VFIO_UNBIND_TIMEOUT) { + if (!virFileExists(path)) + break; + sleep(1);