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| author | Thomas Hellstrom <thellstrom@vmware.com> | 2012-11-06 11:31:49 +0000 |
|---|---|---|
| committer | Ben Hutchings <ben@decadent.org.uk> | 2013-04-25 20:25:38 +0100 |
| commit | 3fa8ee5fafec620e0dadb3ce226124a75d599288 (patch) | |
| tree | f841664a42467710e6ebbceb1ffc8ed3ea45d73a /lib/kobject.c | |
| parent | 595b57bbaf350dceda50bb2021153ab0bf7632b2 (diff) | |
| download | lwn-3fa8ee5fafec620e0dadb3ce226124a75d599288.tar.gz lwn-3fa8ee5fafec620e0dadb3ce226124a75d599288.zip | |
kref: Implement kref_get_unless_zero v3
commit 4b20db3de8dab005b07c74161cb041db8c5ff3a7 upstream.
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>
[bwh: Backported to 3.2:
- Adjust context
- Add #include <linux/atomic.h>]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Diffstat (limited to 'lib/kobject.c')
0 files changed, 0 insertions, 0 deletions