• Linus Torvalds's avatar
    selinux: don't inline slow-path code into avc_has_perm_noaudit() · a554bea8
    Linus Torvalds authored
    The selinux AVC paths remain some of the hottest (and deepest) codepaths
    at filename lookup time, and we make it worse by having the slow path
    cases take up I$ and stack space even when they don't trigger.  Gcc
    tends to always want to inline functions that are just called once -
    never mind that this might make for slower and worse code in the caller.
    
    So this tries to improve on it a bit by making the slow-path cases
    explicitly separate functions that are marked noinline, causing gcc to
    at least no longer allocate stack space for them unless they are
    actually called.  It also seems to help register allocation a tiny bit,
    since gcc now doesn't take the slow case code into account.
    
    Uninlining the slow path may also allow us to inline the remaining hot
    path into the one caller that actually matters: avc_has_perm_flags().
    I'll have to look at that separately, but both avc_audit() and
    avc_has_perm_noaudit() are now small and lean enough that inlining them
    may make sense.
    Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
    a554bea8
avc.c 22.6 KB