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author | Tejun Heo <htejun@gmail.com> | 2007-06-14 03:45:18 +0900 |
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committer | Greg Kroah-Hartman <gregkh@suse.de> | 2007-07-11 16:09:07 -0700 |
commit | 8619f979898397582e366877fd5feeba7560d70c (patch) | |
tree | 7d0e92d4c17d92a00dfeba2b840bf89657b30607 /init/do_mounts.c | |
parent | b6b4a4399c2a83d1af77c99dee0d0b5cc15ec268 (diff) |
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>
Diffstat (limited to 'init/do_mounts.c')
0 files changed, 0 insertions, 0 deletions