[ 118/150] fb: Yet another band-aid for fixing lockdep mess

Greg Kroah-Hartman
2013-02-26T23:58:26Z

From: Takashi Iwai <tiwai@suse.de>

commit e93a9a868792ad71cdd09d75e5a02d8067473c4e upstream.

I've still got lockdep warnings even after Alan's patch, and it seems that
yet more band aids are required to paper over similar paths for
unbind_con_driver() and unregister_con_driver(). After this hack, lockdep
warnings are finally gone.

Signed-off-by: Takashi Iwai <tiwai@suse.de>
Cc: Alan Cox <alan@linux.intel.com>
Cc: Florian Tobias Schandinat <FlorianSchandinat@gmx.de>
Cc: Jiri Kosina <jkosina@suse.cz>
Tested-by: Sedat Dilek <sedat.dilek@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Dave Airlie <airlied@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/tty/vt/vt.c | 43 +++++++++++++++++++++++++++---------------
drivers/video/console/fbcon.c | 4 +--
drivers/video/fbmem.c | 4 +++
include/linux/console.h | 1
include/linux/vt_kern.h | 2 +
5 files changed, 37 insertions(+), 17 deletions(-)

--- a/drivers/tty/vt/vt.c
+++ b/drivers/tty/vt/vt.c
@@ -3135,6 +3135,18 @@ static int con_is_graphics(const struct
*/
int unbind_con_driver(const struct consw *csw, int first, int last, int deflt)
{
+ int retval;
+
+ console_lock();
+ retval = do_unbind_con_driver(csw, first, last, deflt);
+ console_unlock();
+ return retval;
+}
+EXPORT_SYMBOL(unbind_con_driver);
+
+/* unlocked version of unbind_con_driver() */
+int do_unbind_con_driver(const struct consw *csw, int first, int last, int deflt)
+{
struct module *owner = csw->owner;
const struct consw *defcsw = NULL;
struct con_driver *con_driver = NULL, *con_back = NULL;
@@ -3143,7 +3155,7 @@ int unbind_con_driver(const struct consw
if (!try_module_get(owner))
return -ENODEV;

- console_lock();
+ WARN_CONSOLE_UNLOCKED();

/* check if driver is registered and if it is unbindable */
for (i = 0; i < MAX_NR_CON_DRIVER; i++) {
@@ -3156,10 +3168,8 @@ int unbind_con_driver(const struct consw
}
}

- if (retval) {
- console_unlock();
+ if (retval)
goto err;
- }

retval = -ENODEV;

@@ -3175,15 +3185,11 @@ int unbind_con_driver(const struct consw
}
}

- if (retval) {
- console_unlock();
+ if (retval)
goto err;
- }

- if (!con_is_bound(csw)) {
- console_unlock();
+ if (!con_is_bound(csw))
goto err;
- }

first = max(first, con_driver->first);
last = min(last, con_driver->last);
@@ -3212,13 +3218,12 @@ int unbind_con_driver(const struct consw

/* ignore return value, binding should not fail */
do_bind_con_driver(defcsw, first, last, deflt);
- console_unlock();
err:
module_put(owner);
return retval;

}
-EXPORT_SYMBOL(unbind_con_driver);
+EXPORT_SYMBOL_GPL(do_unbind_con_driver);

static int vt_bind(struct con_driver *con)
{
@@ -3605,9 +3610,18 @@ EXPORT_SYMBOL(register_con_driver);
*/
int unregister_con_driver(const struct consw *csw)
{
- int i, retval = -ENODEV;
+ int retval;

console_lock();
+ retval = do_unregister_con_driver(csw);
+ console_unlock();
+ return retval;
+}
+EXPORT_SYMBOL(unregister_con_driver);
+
+int do_unregister_con_driver(const struct consw *csw)
+{
+ int i, retval = -ENODEV;

/* cannot unregister a bound driver */
if (con_is_bound(csw))
@@ -3633,10 +3647,9 @@ int unregister_con_driver(const struct c
}
}
err:
- console_unlock();
return retval;
}
-EXPORT_SYMBOL(unregister_con_driver);
+EXPORT_SYMBOL_GPL(do_unregister_con_driver);

/*
* If we support more console drivers, this function is used
--- a/drivers/video/console/fbcon.c
+++ b/drivers/video/console/fbcon.c
@@ -3010,7 +3010,7 @@ static int fbcon_unbind(void)
{
int ret;

- ret = unbind_con_driver(&fb_con, first_fb_vc, last_fb_vc,
+ ret = do_unbind_con_driver(&fb_con, first_fb_vc, last_fb_vc,
fbcon_is_default);

if (!ret)
@@ -3083,7 +3083,7 @@ static int fbcon_fb_unregistered(struct
primary_device = -1;

if (!num_registered_fb)
- unregister_con_driver(&fb_con);
+ do_unregister_con_driver(&fb_con);

return 0;
}
--- a/drivers/video/fbmem.c
+++ b/drivers/video/fbmem.c
@@ -1668,8 +1668,10 @@ static int do_unregister_framebuffer(str

if (!lock_fb_info(fb_info))
return -ENODEV;
+ console_lock();
event.info = fb_info;
ret = fb_notifier_call_chain(FB_EVENT_FB_UNBIND, &event);
+ console_unlock();
unlock_fb_info(fb_info);

if (ret)
@@ -1684,7 +1686,9 @@ static int do_unregister_framebuffer(str
num_registered_fb--;
fb_cleanup_device(fb_info);
event.info = fb_info;
+ console_lock();
fb_notifier_call_chain(FB_EVENT_FB_UNREGISTERED, &event);
+ console_unlock();

/* this may free fb info */
put_fb_info(fb_info);
--- a/include/linux/console.h
+++ b/include/linux/console.h
@@ -77,6 +77,7 @@ extern const struct consw prom_con; /* S
int con_is_bound(const struct consw *csw);
int register_con_driver(const struct consw *csw, int first, int last);
int unregister_con_driver(const struct consw *csw);
+int do_unregister_con_driver(const struct consw *csw);
int take_over_console(const struct consw *sw, int first, int last, int deflt);
int do_take_over_console(const struct consw *sw, int first, int last, int deflt);
void give_up_console(const struct consw *sw);
--- a/include/linux/vt_kern.h
+++ b/include/linux/vt_kern.h
@@ -131,6 +131,8 @@ void vt_event_post(unsigned int event, u
int vt_waitactive(int n);
void change_console(struct vc_data *new_vc);
void reset_vc(struct vc_data *vc);
+extern int do_unbind_con_driver(const struct consw *csw, int first, int last,
+ int deflt);
extern int unbind_con_driver(const struct consw *csw, int first, int last,
int deflt);
int vty_init(const struct file_operations *console_fops);