This is the usual amount of whitespace. A couple of examples

https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/lin...

https://github.com/apple/darwin-xnu/blob/master/libsyscall/m...

To my eyes this seemed like a completely normal amount of whitespace. The only thing I personally prefer that you would reasonably reduce is moving the left block delimiter from its own line (But left block braces being on their own line is fairly common for C/C++ projects afaik)

Allman style. More popular in the error before pretty printing editors, to help visualize the blocks.