On Mon, 11 Nov 2019 18:23:22 +0100
Greg KH [off-list ref] wrote:

On Mon, Nov 11, 2019 at 08:47:12AM -0800, Stephen Hemminger wrote:

quoted

On Mon, 11 Nov 2019 01:49:20 -0800
"Greg KH" [off-list ref] wrote:
  

quoted

quoted

+	ret = sysfs_create_bin_file(&channel->kobj,    

&ring_buffer_bin_attr);  

quoted

+	if (ret)
+		dev_notice(&dev->device,
+			   "sysfs create ring bin file failed; %d\n",    

ret);  

quoted

+    

Again, don't create sysfs files on your own, the bus code should be
doing this for you automatically and in a way that is race-free.

thanks,

greg k-h  

The sysfs file is only created if the VFIO/UIO driveris used.  

That's even worse.  Again, sysfs files should be automatically created
by the driver core when the device is created.  To randomly add/remove
random files after that happens means userspace is never notified of
that and that's not good.

We've been working for a while to fix up these types of races, don't
purposfully add new ones for no good reason please :)

thanks,

greg k-h

The handler for this sysfs file is in the vfio (and uio) driver.
How would this work if bus handled it?