[PATCH v2] nodedev: transient mdev update on nodeDeviceCreateXML

[Jonathon Jongsma]

On 6/30/23 6:34 AM, Boris Fiuczynski wrote:
> Update the optional mdev attributes by running an mdevctl update on a
> new created nodedev object representing an mdev.
> 
> Resolves: https://bugzilla.redhat.com/show_bug.cgi?id=2143158
> Signed-off-by: Boris Fiuczynski <fiuczy at linux.ibm.com>
> ---
>   src/node_device/node_device_udev.c | 12 ++++++++++--
>   1 file changed, 10 insertions(+), 2 deletions(-)
> 
> diff --git a/src/node_device/node_device_udev.c b/src/node_device/node_device_udev.c
> index 4c37ec3189..fce4212728 100644
> --- a/src/node_device/node_device_udev.c
> +++ b/src/node_device/node_device_udev.c
> @@ -1757,12 +1757,20 @@ nodeStateCleanup(void)
>   static int
>   udevHandleOneDevice(struct udev_device *device)
>   {
> +    virNodeDevCapType dev_cap_type;
>       const char *action = udev_device_get_action(device);
>   
>       VIR_DEBUG("udev action: '%s': %s", action, udev_device_get_syspath(device));
>   
> -    if (STREQ(action, "add") || STREQ(action, "change"))
> -        return udevAddOneDevice(device);
> +    if (STREQ(action, "add") || STREQ(action, "change")) {
> +        int ret = udevAddOneDevice(device);
> +        if (ret == 0 &&
> +            udevGetDeviceType(device, &dev_cap_type) == 0 &&
> +            dev_cap_type == VIR_NODE_DEV_CAP_MDEV)
> +            if (nodeDeviceUpdateMediatedDevices() < 0)
> +                VIR_WARN("mdevctl failed to update mediated devices");
> +        return ret;
> +    }
>   
>       if (STREQ(action, "remove"))
>           return udevRemoveOneDevice(device);


So, this should work and roughly matches what we've done for other 
similar cases. But this is running from within the udev event handler 
thread, and theoretically there could already be an mdevctl thread 
running concurrently and updating the internal device list. The device 
list update functions are thread-safe so I don't think it'll corrupt 
anything, but it seems better to do all mdevctl updates from  mdevctl 
update thread rather than calling it directly here. The same actually 
applies to a couple other existing calls to 
nodeDeviceUpdateMediatedDevices(). I'll send a couple patches that apply 
on top of yours and refactor things a bit. Let me know what you think.

Jonathon