summaryrefslogtreecommitdiff
path: root/include/linux
diff options
context:
space:
mode:
authorJeff Layton <jlayton@poochiereds.net>2016-04-22 03:51:56 +0300
committerAnna Schumaker <Anna.Schumaker@Netapp.com>2016-05-09 16:05:40 +0300
commit62dbef2ae41393eba2f6853ca174130f2d09c7d3 (patch)
treec042592a7ea30cb95d46670142e06f73d7b1d545 /include/linux
parentc065d229e308ede426a3608cf480c61983b36fb8 (diff)
downloadlinux-62dbef2ae41393eba2f6853ca174130f2d09c7d3.tar.xz
sunrpc: add a get_rpccred_rcu inline
Sometimes we might have a RCU managed credential pointer and don't want to use locking to handle it. Add a function that will take a reference to the cred iff the refcount is not already zero. Callers can dereference the pointer under the rcu_read_lock and use that function to take a reference only if the cred is not on its way to destruction. Signed-off-by: Jeff Layton <jeff.layton@primarydata.com> Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
Diffstat (limited to 'include/linux')
-rw-r--r--include/linux/sunrpc/auth.h18
1 files changed, 18 insertions, 0 deletions
diff --git a/include/linux/sunrpc/auth.h b/include/linux/sunrpc/auth.h
index 16bd8f8fef8c..6f36b2bf3e05 100644
--- a/include/linux/sunrpc/auth.h
+++ b/include/linux/sunrpc/auth.h
@@ -206,5 +206,23 @@ struct rpc_cred * get_rpccred(struct rpc_cred *cred)
return cred;
}
+/**
+ * get_rpccred_rcu - get a reference to a cred using rcu-protected pointer
+ * @cred: cred of which to take a reference
+ *
+ * In some cases, we may have a pointer to a credential to which we
+ * want to take a reference, but don't already have one. Because these
+ * objects are freed using RCU, we can access the cr_count while its
+ * on its way to destruction and only take a reference if it's not already
+ * zero.
+ */
+static inline struct rpc_cred *
+get_rpccred_rcu(struct rpc_cred *cred)
+{
+ if (atomic_inc_not_zero(&cred->cr_count))
+ return cred;
+ return NULL;
+}
+
#endif /* __KERNEL__ */
#endif /* _LINUX_SUNRPC_AUTH_H */