• Ondrej Mosnacek's avatar
    selinux: prepare for inlining of hashtab functions · 24def7bb
    Ondrej Mosnacek authored
    Refactor searching and inserting into hashtabs to pave the way for
    converting hashtab_search() and hashtab_insert() to inline functions in
    the next patch. This will avoid indirect calls and allow the compiler to
    better optimize individual callers, leading to a significant performance
    improvement.
    
    In order to avoid the indirect calls, the key hashing and comparison
    callbacks need to be extracted from the hashtab struct and passed
    directly to hashtab_search()/_insert() by the callers so that the
    callback address is always known at compile time. The kernel's
    rhashtable library (<linux/rhashtable*.h>) does the same thing.
    
    This of course makes the hashtab functions slightly easier to misuse by
    passing a wrong callback set, but unfortunately there is no better way
    to implement a hash table that is both generic and efficient in C. This
    patch tries to somewhat mitigate this by only calling the hashtab
    functions in the same file where the corresponding callbacks are
    defined (wrapping them into more specialized functions as needed).
    
    Note that this patch doesn't bring any benefit without also moving the
    definitions of hashtab_search() and -_insert() to the header file, which
    is done in a follow-up patch for easier review of the hashtab.c changes
    in this patch.
    Signed-off-by: default avatarOndrej Mosnacek <omosnace@redhat.com>
    Acked-by: default avatarStephen Smalley <stephen.smalley.work@gmail.com>
    Signed-off-by: default avatarPaul Moore <paul@paul-moore.com>
    24def7bb
hashtab.h 2.41 KB