On Tue, Jun 22, 2021 at 08:27:13AM -0700, Luis Chamberlain wrote:

On Tue, Jun 22, 2021 at 09:41:23AM +0200, Greg KH wrote:

quoted

On Mon, Jun 21, 2021 at 04:36:34PM -0700, Luis Chamberlain wrote:

quoted

+	ssize_t __ret; \
+	if (!try_module_get(THIS_MODULE)) \

try_module_get(THIS_MODULE) is always racy and probably does not do what
you want it to do.  You always want to get/put module references from
code that is NOT the code calling these functions.

In this case, we want it to trump module removal if it succeeds. That's all.

True, but either you stop the race, or you do not right?  If you are so
invested in your load/unload test, this should show up with this code
eventually as well.

quoted

quoted

+		return -ENODEV; \
+	__ret = _name ## _store(dev, attr, buf, len); \
+	module_put(THIS_MODULE); \

This too is going to be racy.

While fun to poke at, I still think this is pointless.

If you have a better idea, which does not "DOS" module removal, please
let me know!

I have yet to understand why you think that the load/unload in a loop is
a valid use case.

thanks,

greg k-h