So I finally have an arm64 laptop that I'm playing with, and as a
result building the kernel the way I usually do - with warnings as
errors.
And I get this:
drivers/net/wireguard/allowedips.c: In function ‘root_remove_peer_lists’:
drivers/net/wireguard/allowedips.c:77:1: error: the frame size of
1040 bytes is larger than 1024 bytes [-Werror=frame-larger-than=]
77 | }
| ^
drivers/net/wireguard/allowedips.c: In function ‘root_free_rcu’:
drivers/net/wireguard/allowedips.c:64:1: error: the frame size of
1040 bytes is larger than 1024 bytes [-Werror=frame-larger-than=]
64 | }
| ^
and clearly it only happens for me because it turns out Asahi has for
some odd reason picked that low CONFIG_FRAME_WARN of just 1kB.
So the fix for the warning was just to update my .config file, no biggie.
But when I look at the code that generates that warning, it just
worries me. It has that magical constant 128.
Sure, that same constant is also in push_rcu().
And there it is randomly as a warning, and then it will happily
overflow the stack frame.
That's not ok.
I think that
(a) that constant should be a bit lower, so that we *can* use a 1kB
stack frame warning on 64-bit architectures
(b) it should be documented some way as a #define
(c) push_rcu() should damn well not "warn and corrupt the stack". It
should warn-and-not-corrupt the stack, even if that then means that
the thing isn't pushed at all.
Hmm?
Linus
