• Michel Lespinasse's avatar
    rbtree: empty nodes have no color · 4c199a93
    Michel Lespinasse authored
    Empty nodes have no color.  We can make use of this property to simplify
    the code emitted by the RB_EMPTY_NODE and RB_CLEAR_NODE macros.  Also,
    we can get rid of the rb_init_node function which had been introduced by
    commit 88d19cf3 ("timers: Add rb_init_node() to allow for stack
    allocated rb nodes") to avoid some issue with the empty node's color not
    being initialized.
    
    I'm not sure what the RB_EMPTY_NODE checks in rb_prev() / rb_next() are
    doing there, though.  axboe introduced them in commit 10fd48f2
    ("rbtree: fixed reversed RB_EMPTY_NODE and rb_next/prev").  The way I
    see it, the 'empty node' abstraction is only used by rbtree users to
    flag nodes that they haven't inserted in any rbtree, so asking the
    predecessor or successor of such nodes doesn't make any sense.
    
    One final rb_init_node() caller was recently added in sysctl code to
    implement faster sysctl name lookups.  This code doesn't make use of
    RB_EMPTY_NODE at all, and from what I could see it only called
    rb_init_node() under the mistaken assumption that such initialization was
    required before node insertion.
    
    [sfr@canb.auug.org.au: fix net/ceph/osd_client.c build]
    Signed-off-by: default avatarMichel Lespinasse <walken@google.com>
    Cc: Andrea Arcangeli <aarcange@redhat.com>
    Acked-by: default avatarDavid Woodhouse <David.Woodhouse@intel.com>
    Cc: Rik van Riel <riel@redhat.com>
    Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
    Cc: Daniel Santos <daniel.santos@pobox.com>
    Cc: Jens Axboe <axboe@kernel.dk>
    Cc: "Eric W. Biederman" <ebiederm@xmission.com>
    Cc: John Stultz <john.stultz@linaro.org>
    Signed-off-by: default avatarStephen Rothwell <sfr@canb.auug.org.au>
    Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
    Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
    4c199a93
proc_sysctl.c 39 KB