From: Thomas Hellstrom Date: Tue, 6 Nov 2012 11:31:49 +0000 (+0000) Subject: kref: Implement kref_get_unless_zero v3 X-Git-Tag: v3.8-rc1~82^2~149 X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=4b20db3de8dab005b07c74161cb041db8c5ff3a7;p=pandora-kernel.git 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 Signed-off-by: Dave Airlie --- Reading git-diff-tree failed