Re: [PATCH 1/2] fs/efivarfs: restrict inode permissions

Linus Torvalds writes: (Summary) wrote:

[...]

we just add a delay to each call so that we can't exceed the limit. Delaying sounds ok, I guess.
Delaying sounds ok, I guess.
But the "obvious" implementation may be simple: But the "obvious" implementation may be simple: static void efi_ratelimit(void)

    {
        static DEFINE_RATELIMIT_STATE(ratelimit, HZ, 100);

If you put this all inside a lock like a mutex, you can generate
basically arbitrary delays, and you're back to the DoS schenario. A
fair lock will allow thousands of waiters to line up and make the
delay be

But maybe I'm missing some really obvious way. Then one user cannot delay another one.