diff options
| author | Thomas Hellstrom <thellstrom@vmware.com> | 2012-11-06 11:31:49 +0000 |
|---|---|---|
| committer | Dave Airlie <airlied@redhat.com> | 2012-11-20 16:15:02 +1000 |
| commit | 4b20db3de8dab005b07c74161cb041db8c5ff3a7 (patch) | |
| tree | 894e7d485b2e5d2b1ae0652b55dcd0f3f249fe8b /include/linux/genhd.h | |
| parent | d7144556195ab04a148e722a93103da5438bdf78 (diff) | |
kref: Implement kref_get_unless_zero v3
This function is intended to simplify locking around refcounting for
objects that can be looked up from a lookup structure, and which are
removed from that lookup structure in the object destructor.
Operations on such objects require at least a read lock around
lookup + kref_get, and a write lock around kref_put + remove from lookup
structure. Furthermore, RCU implementations become extremely tricky.
With a lookup followed by a kref_get_unless_zero *with return value check*
locking in the kref_put path can be deferred to the actual removal from
the lookup structure and RCU lookups become trivial.
v2: Formatting fixes.
v3: Invert the return value.
Signed-off-by: Thomas Hellstrom <thellstrom@vmware.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>
Diffstat (limited to 'include/linux/genhd.h')
0 files changed, 0 insertions, 0 deletions