SUNRPC: Skip zero-refcount transports

When looking for the next transport to use for an RPC call, skip those
that are in the process of being destroyed and that have a zero refcount.

Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>

diff --git a/net/sunrpc/xprtmultipath.c b/net/sunrpc/xprtmultipath.c
index 5df4e7a..c12778e 100644 (file)
--- a/net/sunrpc/xprtmultipath.c
+++ b/net/sunrpc/xprtmultipath.c
@@ -193,10 +193,22 @@ void xprt_iter_default_rewind(struct rpc_xprt_iter *xpi)
        WRITE_ONCE(xpi->xpi_cursor, NULL);
 }
 
+static
+bool xprt_is_active(const struct rpc_xprt *xprt)
+{
+       return kref_read(&xprt->kref) != 0;
+}
+
 static
 struct rpc_xprt *xprt_switch_find_first_entry(struct list_head *head)
 {
-       return list_first_or_null_rcu(head, struct rpc_xprt, xprt_switch);
+       struct rpc_xprt *pos;
+
+       list_for_each_entry_rcu(pos, head, xprt_switch) {
+               if (xprt_is_active(pos))
+                       return pos;
+       }
+       return NULL;
 }
 
 static
@@ -214,9 +226,12 @@ struct rpc_xprt *xprt_switch_find_current_entry(struct list_head *head,
                const struct rpc_xprt *cur)
 {
        struct rpc_xprt *pos;
+       bool found = false;
 
        list_for_each_entry_rcu(pos, head, xprt_switch) {
                if (cur == pos)
+                       found = true;
+               if (found && xprt_is_active(pos))
                        return pos;
        }
        return NULL;
@@ -261,9 +276,12 @@ struct rpc_xprt *xprt_switch_find_next_entry(struct list_head *head,
                const struct rpc_xprt *cur)
 {
        struct rpc_xprt *pos, *prev = NULL;
+       bool found = false;
 
        list_for_each_entry_rcu(pos, head, xprt_switch) {
                if (cur == prev)
+                       found = true;
+               if (found && xprt_is_active(pos))
                        return pos;
                prev = pos;
        }