driver core: do not wait unnecessarily in driver_unregister()

Ingo reported that built-in drivers suffered bootup hangs with certain
driver unregistry sequences, due to sysfs breakage.

Do the minimal fix for v2.6.21: only wait if the driver is a module.

Acked-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 8 insertions, 1 deletions

diff --git a/drivers/base/driver.c b/drivers/base/driver.c
index 1214cbd17d86..082bfded3854 100644
--- a/drivers/base/driver.c
+++ b/drivers/base/driver.c
@@ -183,7 +183,14 @@ int driver_register(struct device_driver * drv)
 void driver_unregister(struct device_driver * drv)
 {
         bus_remove_driver(drv);
-        wait_for_completion(&drv->unloaded);
+        /*
+         * If the driver is a module, we are probably in
+         * the module unload path, and we want to wait
+         * for everything to unload before we can actually
+         * finish the unload.
+         */
+        if (drv->owner)
+                wait_for_completion(&drv->unloaded);
 }
 
 /**