[patch 003/100] fbdev: fix info->lock deadlock in fbcon_event_notify()

Chris Wright
2009-04-23T07:37:43Z

[-- Attachment #1: fbdev-fix-info-lock-deadlock-in-fbcon_event_notify.patch --]
[-- Type: text/plain, Size: 7326 bytes --]

-stable review patch. If anyone has any objections, please let us know.
---------------------

From: Andrea Righi <righi.andrea@gmail.com>

upstream commit: 513adb58685615b0b1d47a3f0d40f5352beff189

fb_notifier_call_chain() is called with info->lock held, i.e. in
do_fb_ioctl() => FBIOPUT_VSCREENINFO => fb_set_var() and the some
notifier callbacks, like fbcon_event_notify(), try to re-acquire
info->lock again.

Remove the lock/unlock_fb_info() in all the framebuffer notifier
callbacks' and be sure to always call fb_notifier_call_chain() with
info->lock held.

[fixes hang caused by 66c1ca01]

Reported-by: Pavel Roskin <proski@gnu.org>
Reported-by: Eric Miao <eric.y.miao@gmail.com>
Signed-off-by: Andrea Righi <righi.andrea@gmail.com>
Cc: Stefan Richter <stefanr@s5r6.in-berlin.de>
Cc: Krzysztof Helt <krzysztof.h1@poczta.fm>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: "Rafael J. Wysocki" <rjw@sisk.pl>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Chris Wright <chrisw@sous-sol.org>
---
drivers/video/backlight/backlight.c | 3 -
drivers/video/backlight/lcd.c | 3 -
drivers/video/console/fbcon.c | 55 +-----------------------------------
drivers/video/fbmem.c | 19 ++++++++++++
4 files changed, 22 insertions(+), 58 deletions(-)

--- a/drivers/video/backlight/backlight.c
+++ b/drivers/video/backlight/backlight.c
@@ -35,8 +35,6 @@ static int fb_notifier_callback(struct n
return 0;

bd = container_of(self, struct backlight_device, fb_notif);
- if (!lock_fb_info(evdata->info))
- return -ENODEV;
mutex_lock(&bd->ops_lock);
if (bd->ops)
if (!bd->ops->check_fb ||
@@ -49,7 +47,6 @@ static int fb_notifier_callback(struct n
backlight_update_status(bd);
}
mutex_unlock(&bd->ops_lock);
- unlock_fb_info(evdata->info);
return 0;
}

--- a/drivers/video/backlight/lcd.c
+++ b/drivers/video/backlight/lcd.c
@@ -40,8 +40,6 @@ static int fb_notifier_callback(struct n
if (!ld->ops)
return 0;

- if (!lock_fb_info(evdata->info))
- return -ENODEV;
mutex_lock(&ld->ops_lock);
if (!ld->ops->check_fb || ld->ops->check_fb(ld, evdata->info)) {
if (event == FB_EVENT_BLANK) {
@@ -53,7 +51,6 @@ static int fb_notifier_callback(struct n
}
}
mutex_unlock(&ld->ops_lock);
- unlock_fb_info(evdata->info);
return 0;
}

--- a/drivers/video/console/fbcon.c
+++ b/drivers/video/console/fbcon.c
@@ -2263,9 +2263,12 @@ static void fbcon_generic_blank(struct v
}

+ if (!lock_fb_info(info))
+ return;
event.info = info;
event.data = &blank;
fb_notifier_call_chain(FB_EVENT_CONBLANK, &event);
+ unlock_fb_info(info);
}

static int fbcon_blank(struct vc_data *vc, int blank, int mode_switch)
@@ -2956,8 +2959,6 @@ static int fbcon_fb_unregistered(struct
{
int i, idx;

- if (!lock_fb_info(info))
- return -ENODEV;
idx = info->node;
for (i = first_fb_vc; i <= last_fb_vc; i++) {
if (con2fb_map[i] == idx)
@@ -2985,8 +2986,6 @@ static int fbcon_fb_unregistered(struct
if (primary_device == idx)
primary_device = -1;

- unlock_fb_info(info);
-
if (!num_registered_fb)
unregister_con_driver(&fb_con);

@@ -3027,11 +3026,8 @@ static int fbcon_fb_registered(struct fb
{
int ret = 0, i, idx;

- if (!lock_fb_info(info))
- return -ENODEV;
idx = info->node;
fbcon_select_primary(info);
- unlock_fb_info(info);

if (info_idx == -1) {
for (i = first_fb_vc; i <= last_fb_vc; i++) {
@@ -3152,53 +3148,23 @@ static int fbcon_event_notify(struct not

switch(action) {
case FB_EVENT_SUSPEND:
- if (!lock_fb_info(info)) {
- ret = -ENODEV;
- goto done;
- }
fbcon_suspended(info);
- unlock_fb_info(info);
break;
case FB_EVENT_RESUME:
- if (!lock_fb_info(info)) {
- ret = -ENODEV;
- goto done;
- }
fbcon_resumed(info);
- unlock_fb_info(info);
break;
case FB_EVENT_MODE_CHANGE:
- if (!lock_fb_info(info)) {
- ret = -ENODEV;
- goto done;
- }
fbcon_modechanged(info);
- unlock_fb_info(info);
break;
case FB_EVENT_MODE_CHANGE_ALL:
- if (!lock_fb_info(info)) {
- ret = -ENODEV;
- goto done;
- }
fbcon_set_all_vcs(info);
- unlock_fb_info(info);
break;
case FB_EVENT_MODE_DELETE:
mode = event->data;
- if (!lock_fb_info(info)) {
- ret = -ENODEV;
- goto done;
- }
ret = fbcon_mode_deleted(info, mode);
- unlock_fb_info(info);
break;
case FB_EVENT_FB_UNBIND:
- if (!lock_fb_info(info)) {
- ret = -ENODEV;
- goto done;
- }
idx = info->node;
- unlock_fb_info(info);
ret = fbcon_fb_unbind(idx);
break;
case FB_EVENT_FB_REGISTERED:
@@ -3217,29 +3183,14 @@ static int fbcon_event_notify(struct not
con2fb->framebuffer = con2fb_map[con2fb->console - 1];
break;
case FB_EVENT_BLANK:
- if (!lock_fb_info(info)) {
- ret = -ENODEV;
- goto done;
- }
fbcon_fb_blanked(info, *(int *)event->data);
- unlock_fb_info(info);
break;
case FB_EVENT_NEW_MODELIST:
- if (!lock_fb_info(info)) {
- ret = -ENODEV;
- goto done;
- }
fbcon_new_modelist(info);
- unlock_fb_info(info);
break;
case FB_EVENT_GET_REQ:
caps = event->data;
- if (!lock_fb_info(info)) {
- ret = -ENODEV;
- goto done;
- }
fbcon_get_requirement(info, caps);
- unlock_fb_info(info);
break;
}
done:
--- a/drivers/video/fbmem.c
+++ b/drivers/video/fbmem.c
@@ -1086,8 +1086,11 @@ static long do_fb_ioctl(struct fb_info *
return -EINVAL;
con2fb.framebuffer = -1;
event.data = &con2fb;
+ if (!lock_fb_info(info))
+ return -ENODEV;
event.info = info;
fb_notifier_call_chain(FB_EVENT_GET_CONSOLE_MAP, &event);
+ unlock_fb_info(info);
ret = copy_to_user(argp, &con2fb, sizeof(con2fb)) ? -EFAULT : 0;
break;
case FBIOPUT_CON2FBMAP:
@@ -1104,8 +1107,11 @@ static long do_fb_ioctl(struct fb_info *
break;
}
event.data = &con2fb;
+ if (!lock_fb_info(info))
+ return -ENODEV;
event.info = info;
ret = fb_notifier_call_chain(FB_EVENT_SET_CONSOLE_MAP, &event);
+ unlock_fb_info(info);
break;
case FBIOBLANK:
if (!lock_fb_info(info))
@@ -1510,7 +1516,10 @@ register_framebuffer(struct fb_info *fb_
registered_fb[i] = fb_info;

event.info = fb_info;
+ if (!lock_fb_info(fb_info))
+ return -ENODEV;
fb_notifier_call_chain(FB_EVENT_FB_REGISTERED, &event);
+ unlock_fb_info(fb_info);
return 0;
}

@@ -1544,8 +1553,12 @@ unregister_framebuffer(struct fb_info *f
goto done;
}

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

if (ret) {
ret = -EINVAL;
@@ -1579,6 +1592,8 @@ void fb_set_suspend(struct fb_info *info
{
struct fb_event event;

+ if (!lock_fb_info(info))
+ return;
event.info = info;
if (state) {
fb_notifier_call_chain(FB_EVENT_SUSPEND, &event);
@@ -1587,6 +1602,7 @@ void fb_set_suspend(struct fb_info *info
info->state = FBINFO_STATE_RUNNING;
fb_notifier_call_chain(FB_EVENT_RESUME, &event);
}
+ unlock_fb_info(info);
}

/**
@@ -1656,8 +1672,11 @@ int fb_new_modelist(struct fb_info *info
err = 1;

if (!list_empty(&info->modelist)) {
+ if (!lock_fb_info(info))
+ return -ENODEV;
event.info = info;
err = fb_notifier_call_chain(FB_EVENT_NEW_MODELIST, &event);
+ unlock_fb_info(info);
}

return err;