greybus: use a simple list of hd connections

First of all, there's a bug in _gb_hd_connection_insert, which
Viresh found.  But pointing out that problem just called attention
to the fact that I have planning to to remove the affected block of
code.

The set of connections associated with a host device is currently
maintained in a red-black tree.  The number of connections we're
likely to have is on the order of a hundred, and at least for now
isn't even going to approach that.  When this code first went in,
Greg asserted that using a list is speedier than a red-black tree
for smallish numbers of elements (maybe up to a few hundred?).

So this patch just removes the host device's red-black tree of
connections, using a simple list instead.

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

diff --git a/drivers/staging/greybus/connection.c b/drivers/staging/greybus/connection.c
index 5927f2d979c280ca01bc942b31befb66714108b9..ecd7931e024da1293b2f4dfab9c5c56264a6f693 100644 (file)
--- a/drivers/staging/greybus/connection.c
+++ b/drivers/staging/greybus/connection.c
@@ -13,51 +13,15 @@
 
 static DEFINE_SPINLOCK(gb_connections_lock);
 
-static void _gb_hd_connection_insert(struct greybus_host_device *hd,
-                                       struct gb_connection *connection)
-{
-       struct rb_root *root = &hd->connections;
-       struct rb_node *node = &connection->hd_node;
-       struct rb_node **link = &root->rb_node;
-       struct rb_node *above = NULL;
-       u16 cport_id = connection->hd_cport_id;
-
-       while (*link) {
-               struct gb_connection *_connection;
-
-               above = *link;
-               _connection = rb_entry(above, struct gb_connection, hd_node);
-               if (_connection->hd_cport_id > cport_id)
-                       link = &above->rb_left;
-               else if (_connection->hd_cport_id < cport_id)
-                       link = &above->rb_right;
-       }
-       rb_link_node(node, above, link);
-       rb_insert_color(node, root);
-}
-
-static void _gb_hd_connection_remove(struct gb_connection *connection)
-{
-       rb_erase(&connection->hd_node, &connection->hd->connections);
-}
-
 struct gb_connection *gb_hd_connection_find(struct greybus_host_device *hd,
                                                u16 cport_id)
 {
        struct gb_connection *connection = NULL;
-       struct rb_node *node;
 
        spin_lock_irq(&gb_connections_lock);
-       node = hd->connections.rb_node;
-       while (node) {
-               connection = rb_entry(node, struct gb_connection, hd_node);
-               if (connection->hd_cport_id > cport_id)
-                       node = node->rb_left;
-               else if (connection->hd_cport_id < cport_id)
-                       node = node->rb_right;
-               else
+       list_for_each_entry(connection, &hd->connections, hd_links)
+               if (connection->hd_cport_id == cport_id)
                        goto found;
-       }
        connection = NULL;
  found:
        spin_unlock_irq(&gb_connections_lock);
@@ -204,7 +168,7 @@ struct gb_connection *gb_connection_create(struct gb_interface *interface,
        }
 
        spin_lock_irq(&gb_connections_lock);
-       _gb_hd_connection_insert(hd, connection);
+       list_add_tail(&connection->hd_links, &hd->connections);
        list_add_tail(&connection->interface_links, &interface->connections);
        spin_unlock_irq(&gb_connections_lock);
 
@@ -233,7 +197,7 @@ void gb_connection_destroy(struct gb_connection *connection)
        }
        spin_lock_irq(&gb_connections_lock);
        list_del(&connection->interface_links);
-       _gb_hd_connection_remove(connection);
+       list_del(&connection->hd_links);
        spin_unlock_irq(&gb_connections_lock);
 
        gb_connection_hd_cport_id_free(connection);

diff --git a/drivers/staging/greybus/connection.h b/drivers/staging/greybus/connection.h
index 3aa86955b748df2e42616a145c5a1b6c56d15def..5e969672b7938ac444c45db3791aa417188214aa 100644 (file)
--- a/drivers/staging/greybus/connection.h
+++ b/drivers/staging/greybus/connection.h
@@ -28,7 +28,7 @@ struct gb_connection {
        u16                             hd_cport_id;
        u16                             interface_cport_id;
 
-       struct rb_node                  hd_node;
+       struct list_head                hd_links;
        struct list_head                interface_links;
 
        struct gb_protocol              *protocol;

diff --git a/drivers/staging/greybus/core.c b/drivers/staging/greybus/core.c
index 9567324c71ec8f50144366f7eb869c412a98169f..96bd97481cf2c698a6c5b8dba5cdb5212a092bb3 100644 (file)
--- a/drivers/staging/greybus/core.c
+++ b/drivers/staging/greybus/core.c
@@ -186,7 +186,7 @@ struct greybus_host_device *greybus_create_hd(struct greybus_host_driver *driver
        hd->parent = parent;
        hd->driver = driver;
        INIT_LIST_HEAD(&hd->modules);
-       hd->connections = RB_ROOT;
+       INIT_LIST_HEAD(&hd->connections);
        ida_init(&hd->cport_id_map);
        spin_lock_init(&hd->cport_id_map_lock);
 

diff --git a/drivers/staging/greybus/greybus.h b/drivers/staging/greybus/greybus.h
index c86eb25dd38d76aff2862d9cd1c893668108e5f9..bb395280e7d37bc34f976a9cd68b139085b36307 100644 (file)
--- a/drivers/staging/greybus/greybus.h
+++ b/drivers/staging/greybus/greybus.h
@@ -166,7 +166,7 @@ struct greybus_host_device {
        const struct greybus_host_driver *driver;
 
        struct list_head modules;
-       struct rb_root connections;
+       struct list_head connections;
        struct ida cport_id_map;
        spinlock_t cport_id_map_lock;
        u8 device_id;