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authorTejun Heo <htejun@gmail.com>2007-06-13 22:45:18 +0400
committerGreg Kroah-Hartman <gregkh@suse.de>2007-07-12 03:09:07 +0400
commit8619f979898397582e366877fd5feeba7560d70c (patch)
tree7d0e92d4c17d92a00dfeba2b840bf89657b30607 /net/802
parentb6b4a4399c2a83d1af77c99dee0d0b5cc15ec268 (diff)
downloadlinux-8619f979898397582e366877fd5feeba7560d70c.tar.xz
sysfs: slim down sysfs_dirent->s_active
Make sysfs_dirent->s_active an atomic_t instead of rwsem. This reduces the size of sysfs_dirent from 136 to 104 on 64bit and from 76 to 60 on 32bit with lock debugging turned off. With lock debugging turned on the reduction is much larger. s_active starts at zero and each active reference increments s_active. Putting a reference decrements s_active. Deactivation subtracts SD_DEACTIVATED_BIAS which is currently INT_MIN and assumed to be small enough to make s_active negative. If s_active is negative, sysfs_get() no longer grants new references. Deactivation succeeds immediately if there is no active user; otherwise, it waits using a completion for the last put. Due to the removal of lockdep tricks, this change makes things less trickier in release_sysfs_dirent(). As all the complexity is contained in three s_active functions, I think it's more readable this way. Signed-off-by: Tejun Heo <htejun@gmail.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
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