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    pkt_sched: Change misleading code in class delete. · 7cd0a638
    Jarek Poplawski 提交于
    While looking for a possible reason of bugzilla report on HTB oops:
    http://bugzilla.kernel.org/show_bug.cgi?id=12858
    I found the code in htb_delete calling htb_destroy_class on zero
    refcount is very misleading: it can suggest this is a common path, and
    destroy is called under sch_tree_lock. Actually, this can never happen
    like this because before deletion cops->get() is done, and after
    delete a class is still used by tclass_notify. The class destroy is
    always called from cops->put(), so without sch_tree_lock.
    
    This doesn't mean much now (since 2.6.27) because all vulnerable calls
    were moved from htb_destroy_class to htb_delete, but there was a bug
    in older kernels. The same change is done for other classful scheds,
    which, it seems, didn't have similar locking problems here.
    Reported-by: Nm0sia <m0sia@m0sia.ru>
    Signed-off-by: NJarek Poplawski <jarkao2@gmail.com>
    Signed-off-by: NDavid S. Miller <davem@davemloft.net>
    7cd0a638
sch_htb.c 42.0 KB