SUNRPC: Lockless server RPCSEC_GSS context lookup

Use RCU protection for looking up the RPCSEC_GSS context.
Signed-off-by: NTrond Myklebust <trond.myklebust@hammerspace.com>
Signed-off-by: NJ. Bruce Fields <bfields@redhat.com>

net/sunrpc/auth_gss/svcauth_gss.c

@@ -76,6 +76,7 @@ struct rsi {
 	struct xdr_netobj	in_handle, in_token;
 	struct xdr_netobj	out_handle, out_token;
 	int			major_status, minor_status;
+	struct rcu_head		rcu_head;
 };
 
 static struct rsi *rsi_update(struct cache_detail *cd, struct rsi *new, struct rsi *old);
@@ -89,13 +90,21 @@ static void rsi_free(struct rsi *rsii)
 	kfree(rsii->out_token.data);
 }
 
-static void rsi_put(struct kref *ref)
+static void rsi_free_rcu(struct rcu_head *head)
 {
-	struct rsi *rsii = container_of(ref, struct rsi, h.ref);
+	struct rsi *rsii = container_of(head, struct rsi, rcu_head);
+
 	rsi_free(rsii);
 	kfree(rsii);
 }
 
+static void rsi_put(struct kref *ref)
+{
+	struct rsi *rsii = container_of(ref, struct rsi, h.ref);
+
+	call_rcu(&rsii->rcu_head, rsi_free_rcu);
+}
+
 static inline int rsi_hash(struct rsi *item)
 {
 	return hash_mem(item->in_handle.data, item->in_handle.len, RSI_HASHBITS)
@@ -282,7 +291,7 @@ static struct rsi *rsi_lookup(struct cache_detail *cd, struct rsi *item)
 	struct cache_head *ch;
 	int hash = rsi_hash(item);
 
-	ch = sunrpc_cache_lookup(cd, &item->h, hash);
+	ch = sunrpc_cache_lookup_rcu(cd, &item->h, hash);
 	if (ch)
 		return container_of(ch, struct rsi, h);
 	else
@@ -330,6 +339,7 @@ struct rsc {
 	struct svc_cred		cred;
 	struct gss_svc_seq_data	seqdata;
 	struct gss_ctx		*mechctx;
+	struct rcu_head		rcu_head;
 };
 
 static struct rsc *rsc_update(struct cache_detail *cd, struct rsc *new, struct rsc *old);
@@ -343,12 +353,22 @@ static void rsc_free(struct rsc *rsci)
 	free_svc_cred(&rsci->cred);
 }
 
+static void rsc_free_rcu(struct rcu_head *head)
+{
+	struct rsc *rsci = container_of(head, struct rsc, rcu_head);
+
+	kfree(rsci->handle.data);
+	kfree(rsci);
+}
+
 static void rsc_put(struct kref *ref)
 {
 	struct rsc *rsci = container_of(ref, struct rsc, h.ref);
 
-	rsc_free(rsci);
-	kfree(rsci);
+	if (rsci->mechctx)
+		gss_delete_sec_context(&rsci->mechctx);
+	free_svc_cred(&rsci->cred);
+	call_rcu(&rsci->rcu_head, rsc_free_rcu);
 }
 
 static inline int
@@ -542,7 +562,7 @@ static struct rsc *rsc_lookup(struct cache_detail *cd, struct rsc *item)
 	struct cache_head *ch;
 	int hash = rsc_hash(item);
 
-	ch = sunrpc_cache_lookup(cd, &item->h, hash);
+	ch = sunrpc_cache_lookup_rcu(cd, &item->h, hash);
 	if (ch)
 		return container_of(ch, struct rsc, h);
 	else