component: Detach components when deleting master struct

component_master_add_with_match calls find_components which, if any
components already exist, it attaches to the master struct. However, if
we later encounter an error the master struct is deleted, leaving
components with a dangling pointer to it.

If the error was a temporary one, e.g. for probe deferral, then when
the master device is re-probed, it will fail to find the required
components as they appear to already be attached to a master.

Fix this by nulling components pointers to the master struct when it is
deleted. This code is factored out into a separate function so it can be
shared with component_master_del.

Signed-off-by: Jon Medhurst <tixy@linaro.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

1 files changed, 22 insertions, 19 deletions

diff --git a/drivers/base/component.c b/drivers/base/component.c
index 05cd26c02449..2738039aae9e 100644
--- a/drivers/base/component.c
+++ b/drivers/base/component.c
@@ -285,6 +285,24 @@ void component_match_add_release(struct device *master,
 }
 EXPORT_SYMBOL(component_match_add_release);
 
+static void free_master(struct master *master)
+{
+        struct component_match *match = master->match;
+        int i;
+
+        list_del(&master->node);
+
+        if (match) {
+                for (i = 0; i < match->num; i++) {
+                        struct component *c = match->compare[i].component;
+                        if (c)
+                                c->master = NULL;
+                }
+        }
+
+        kfree(master);
+}
+
 int component_master_add_with_match(struct device *dev,
         const struct component_master_ops *ops,
         struct component_match *match)
@@ -311,11 +329,9 @@ int component_master_add_with_match(struct device *dev,
 
         ret = try_to_bring_up_master(master, NULL);
 
-        if (ret < 0) {
-                /* Delete off the list if we weren't successful */
-                list_del(&master->node);
-                kfree(master);
-        }
+        if (ret < 0)
+                free_master(master);
+
         mutex_unlock(&component_mutex);
 
         return ret < 0 ? ret : 0;
@@ -326,25 +342,12 @@ void component_master_del(struct device *dev,
         const struct component_master_ops *ops)
 {
         struct master *master;
-        int i;
 
         mutex_lock(&component_mutex);
         master = __master_find(dev, ops);
         if (master) {
-                struct component_match *match = master->match;
-
                 take_down_master(master);
-
-                list_del(&master->node);
-
-                if (match) {
-                        for (i = 0; i < match->num; i++) {
-                                struct component *c = match->compare[i].component;
-                                if (c)
-                                        c->master = NULL;
-                        }
-                }
-                kfree(master);
+                free_master(master);
         }
         mutex_unlock(&component_mutex);
 }