component: do not dereference opaque pointer in debugfs

The match data does not have to be a struct device pointer, and indeed
very often is not. Attempt to treat it as such easily results in a
crash.

For the components that are not registered, we don't know which device
is missing. Once it it is there, we can use the struct component to get
the device and whether it's bound or not.

Fixes: 59e73854 ('component: add debugfs support')
Signed-off-by: Lubomir Rintel <lkundrak@v3.sk>
Cc: stable <stable@vger.kernel.org>
Cc: Arnaud Pouliquen <arnaud.pouliquen@st.com>
Link: https://lore.kernel.org/r/20191118115431.63626-1-lkundrak@v3.skSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/base/component.c

@@ -101,11 +101,11 @@ static int component_devices_show(struct seq_file *s, void *data)
 	seq_printf(s, "%-40s %20s\n", "device name", "status");
 	seq_puts(s, "-------------------------------------------------------------\n");
 	for (i = 0; i < match->num; i++) {
-		struct device *d = (struct device *)match->compare[i].data;
+		struct component *component = match->compare[i].component;
 
-		seq_printf(s, "%-40s %20s\n", dev_name(d),
-			   match->compare[i].component ?
-			   "registered" : "not registered");
+		seq_printf(s, "%-40s %20s\n",
+			   component ? dev_name(component->dev) : "(unknown)",
+			   component ? (component->bound ? "bound" : "not bound") : "not registered");
 	}
 	mutex_unlock(&component_mutex);