• Tejun Heo's avatar
    sysfs: make attr namespace interface less convoluted · 58292cbe
    Tejun Heo authored
    
    
    sysfs ns (namespace) implementation became more convoluted than
    necessary while trying to hide ns information from visible interface.
    The relatively recent attr ns support is a good example.
    
    * attr ns tag is determined by sysfs_ops->namespace() callback while
      dir tag is determined by kobj_type->namespace().  The placement is
      arbitrary.
    
    * Instead of performing operations with explicit ns tag, the namespace
      callback is routed through sysfs_attr_ns(), sysfs_ops->namespace(),
      class_attr_namespace(), class_attr->namespace().  It's not simpler
      in any sense.  The only thing this convolution does is traversing
      the whole stack backwards.
    
    The namespace callbacks are unncessary because the operations involved
    are inherently synchronous.  The information can be provided in in
    straight-forward top-down direction and reversing that direction is
    unnecessary and against basic design principles.
    
    This backward interface is unnecessarily convoluted and hinders
    properly separating out sysfs from driver model / kobject for proper
    layering.  This patch updates attr ns support such that
    
    * sysfs_ops->namespace() and class_attr->namespace() are dropped.
    
    * sysfs_{create|remove}_file_ns(), which take explicit @ns param, are
      added and sysfs_{create|remove}_file() are now simple wrappers
      around the ns aware functions.
    
    * ns handling is dropped from sysfs_chmod_file().  Nobody uses it at
      this point.  sysfs_chmod_file_ns() can be added later if necessary.
    
    * Explicit @ns is propagated through class_{create|remove}_file_ns()
      and netdev_class_{create|remove}_file_ns().
    
    * driver/net/bonding which is currently the only user of attr
      namespace is updated to use netdev_class_{create|remove}_file_ns()
      with @bh->net as the ns tag instead of using the namespace callback.
    
    This patch should be an equivalent conversion without any functional
    difference.  It makes the code easier to follow, reduces lines of code
    a bit and helps proper separation and layering.
    Signed-off-by: default avatarTejun Heo <tj@kernel.org>
    Cc: Eric W. Biederman <ebiederm@xmission.com>
    Cc: Kay Sievers <kay@vrfy.org>
    Acked-by: default avatarDavid S. Miller <davem@davemloft.net>
    Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
    58292cbe