greybus: connection: check for duplicate cport ids

Check at connection creation time for an attempt to create a
connection with an interface CPort ID that's the same as one that's
already been created.

Define a new helper function to look for such a duplicate.  The
check for a duplicate is only performed at initialization time,
and CPorts are initialized serially for each bundle, so there's
no need to acquire the list lock for this search.

Signed-off-by: Alex Elder <elder@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>

diff --git a/drivers/staging/greybus/connection.c b/drivers/staging/greybus/connection.c
index 8f528c1640e1d2c6eb4a3395098014e1311a5481..ab6c60ec874cdb5b9154d5c70b432d9e0a577f22 100644 (file)
--- a/drivers/staging/greybus/connection.c
+++ b/drivers/staging/greybus/connection.c
@@ -11,10 +11,22 @@
 
 static DEFINE_SPINLOCK(gb_connections_lock);
 
+/* This is only used at initialization time; no locking is required. */
+static struct gb_connection *
+gb_connection_intf_find(struct greybus_host_device *hd, u16 cport_id)
+{
+       struct gb_connection *connection;
+
+       list_for_each_entry(connection, &hd->connections, hd_links)
+               if (connection->intf_cport_id == cport_id)
+                       return connection;
+       return NULL;
+}
+
 static struct gb_connection *
 gb_connection_hd_find(struct greybus_host_device *hd, u16 cport_id)
 {
-       struct gb_connection *connection = NULL;
+       struct gb_connection *connection;
        unsigned long flags;
 
        spin_lock_irqsave(&gb_connections_lock, flags);
@@ -22,7 +34,7 @@ gb_connection_hd_find(struct greybus_host_device *hd, u16 cport_id)
                if (connection->hd_cport_id == cport_id)
                        goto found;
        connection = NULL;
- found:
+found:
        spin_unlock_irqrestore(&gb_connections_lock, flags);
 
        return connection;
@@ -159,21 +171,29 @@ struct gb_connection *gb_connection_create(struct gb_bundle *bundle,
                                u16 cport_id, u8 protocol_id)
 {
        struct gb_connection *connection;
-       struct greybus_host_device *hd;
+       struct greybus_host_device *hd = bundle->intf->hd;
        int retval;
        u8 major = 0;
        u8 minor = 1;
 
+       /*
+        * If a manifest tries to reuse a cport, reject it.  We
+        * initialize connections serially so we don't need to worry
+        * about holding the connection lock.
+        */
+       if (gb_connection_intf_find(hd, cport_id)) {
+               pr_err("duplicate interface cport id 0x%04hx\n", cport_id);
+               return NULL;
+       }
+
        connection = kzalloc(sizeof(*connection), GFP_KERNEL);
        if (!connection)
                return NULL;
 
+       connection->hd = hd;
        connection->protocol_id = protocol_id;
        connection->major = major;
        connection->minor = minor;
-
-       hd = bundle->intf->hd;
-       connection->hd = hd;
        if (!gb_connection_hd_cport_id_alloc(connection)) {
                gb_protocol_put(connection->protocol);
                kfree(connection);