path: root/include/keys/keyring-type.h
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authorDavid Howells <dhowells@redhat.com>2012-05-11 10:56:56 +0100
committerDavid Howells <dhowells@redhat.com>2012-05-11 10:56:56 +0100
commit65d87fe68abf2fc226a9e96be61160f65d6b4680 (patch)
tree23881b6daf54c7522178363f0ae32ddb6c836784 /include/keys/keyring-type.h
parent1eb1bcf5bfad001128293b86d891c9d6f2f27333 (diff)
KEYS: Perform RCU synchronisation on keys prior to key destruction
Make the keys garbage collector invoke synchronize_rcu() prior to destroying keys with a zero usage count. This means that a key can be examined under the RCU read lock in the safe knowledge that it won't get deallocated until after the lock is released - even if its usage count becomes zero whilst we're looking at it. This is useful in keyring search vs key link. Consider a keyring containing a link to a key. That link can be replaced in-place in the keyring without requiring an RCU copy-and-replace on the keyring contents without breaking a search underway on that keyring when the displaced key is released, provided the key is actually destroyed only after the RCU read lock held by the search algorithm is released. This permits __key_link() to replace a key without having to reallocate the key payload. A key gets replaced if a new key being linked into a keyring has the same type and description. Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Jeff Layton <jlayton@redhat.com>
Diffstat (limited to 'include/keys/keyring-type.h')
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