• Tejun Heo's avatar
    idr: remove MAX_IDR_MASK and move left MAX_IDR_* into idr.c · e8c8d1bc
    Tejun Heo authored
    MAX_IDR_MASK is another weirdness in the idr interface.  As idr covers
    whole positive integer range, it's defined as 0x7fffffff or INT_MAX.
    
    Its usage in idr_find(), idr_replace() and idr_remove() is bizarre.
    They basically mask off the sign bit and operate on the rest, so if
    the caller, by accident, passes in a negative number, the sign bit
    will be masked off and the remaining part will be used as if that was
    the input, which is worse than crashing.
    
    The constant is visible in idr.h and there are several users in the
    kernel.
    
    * drivers/i2c/i2c-core.c:i2c_add_numbered_adapter()
    
      Basically used to test if adap->nr is a negative number which isn't
      -1 and returns -EINVAL if so.  idr_alloc() already has negative
      @start checking (w/ WARN_ON_ONCE), so this can go away.
    
    * drivers/infiniband/core/cm.c:cm_alloc_id()
      drivers/infiniband/hw/mlx4/cm.c:id_map_alloc()
    
      Used to wrap cyclic @start.  Can be replaced with max(next, 0).
      Note that this type of cyclic allocation using idr is buggy.  These
      are prone to spurious -ENOSPC failure after the first wraparound.
    
    * fs/super.c:get_anon_bdev()
    
      The ID allocated from ida is masked off before being tested whether
      it's inside valid range.  ida allocated ID can never be a negative
      number and the masking is unnecessary.
    
    Update idr_*() functions to fail with -EINVAL when negative @id is
    specified and update other MAX_IDR_MASK users as described above.
    
    This leaves MAX_IDR_MASK without any user, remove it and relocate
    other MAX_IDR_* constants to lib/idr.c.
    Signed-off-by: default avatarTejun Heo <tj@kernel.org>
    Cc: Jean Delvare <khali@linux-fr.org>
    Cc: Roland Dreier <roland@kernel.org>
    Cc: Sean Hefty <sean.hefty@intel.com>
    Cc: Hal Rosenstock <hal.rosenstock@gmail.com>
    Cc: "Marciniszyn, Mike" <mike.marciniszyn@intel.com>
    Cc: Jack Morgenstein <jackm@dev.mellanox.co.il>
    Cc: Or Gerlitz <ogerlitz@mellanox.com>
    Cc: Al Viro <viro@zeniv.linux.org.uk>
    Acked-by: default avatarWolfram Sang <wolfram@the-dreams.de>
    Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
    Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
    e8c8d1bc
idr.c 28.3 KB