The patch titled
revert "fbdev: fix info->lock deadlock in fbcon_event_notify()"
has been added to the -mm tree. Its filename is
revert-fbdev-fix-info-lock-deadlock-in-fbcon_event_notify.patch
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------------------------------------------------------
Subject: revert "fbdev: fix info->lock deadlock in fbcon_event_notify()"
From: Krzysztof Helt <krzysztof.h1@xxxxx>
A conversion of the BLK to the fb_info->lock mutex brought some circular
locking dependencies. Despite extensive effort to fix these problems
there are still some bugs left. The last effort unveiled a problem
described below. It is not fixable without rethinking how locking should
be done inside the fbdev layer.
Short summary of the lock dep is:
1. sys_munmap() obtains [mm->mmap_sem] and calls indirectly
:: fb_release() obtains [fb_info->lock]
2. fb_ioctl() obtains [fb_info->lock] and calls indirectly
:: fb_notifier_call_chain() obtains [fb_notifier_list->rwsem]
3. driver_probe_device() calls indirectly
:: register_framebuffer() calls indirectly
:: fb_notifier_call_chain() obtains [fb_notifier_list->rwsem] and calls indirectly
:: sysfs_create_dir() obtains [sysfs_mutex]
4. sysfs_readdir() obtains [sysfs_mutex] and calls indirectly
:: copy_to_user() obtains [mm->mmap_sem]
Revert the BKL to mutex conversion patch
(3e680aae4e53ab54cdbb0c29257dae0cbb158e1c) while keeping the patch which
made the fb_ioctl and the fb_compat_ioctl using a common function
(a684e7d33096892093456dd56a582cfc3bfad648).
This patch: revert
: commit 513adb58685615b0b1d47a3f0d40f5352beff189
: Author: Andrea Righi <righi.andrea@xxxxxxxxx>
: Date: Mon Apr 13 14:39:39 2009 -0700
:
: fbdev: fix info->lock deadlock in fbcon_event_notify()
Signed-off-by: Krzysztof Helt <krzysztof.h1@xxxxx>
Cc: Andrea Righi <righi.andrea@xxxxxxxxx>
Cc: Geert Uytterhoeven <geert@xxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
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, 58 insertions(+), 22 deletions(-)
diff -puN drivers/video/backlight/backlight.c~revert-fbdev-fix-info-lock-deadlock-in-fbcon_event_notify drivers/video/backlight/backlight.c
--- a/drivers/video/backlight/backlight.c~revert-fbdev-fix-info-lock-deadlock-in-fbcon_event_notify
+++ a/drivers/video/backlight/backlight.c
@@ -35,6 +35,8 @@ 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 ||
@@ -47,6 +49,7 @@ static int fb_notifier_callback(struct n
backlight_update_status(bd);
}
mutex_unlock(&bd->ops_lock);
+ unlock_fb_info(evdata->info);
return 0;
}
diff -puN drivers/video/backlight/lcd.c~revert-fbdev-fix-info-lock-deadlock-in-fbcon_event_notify drivers/video/backlight/lcd.c
--- a/drivers/video/backlight/lcd.c~revert-fbdev-fix-info-lock-deadlock-in-fbcon_event_notify
+++ a/drivers/video/backlight/lcd.c
@@ -40,6 +40,8 @@ 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) {
@@ -51,6 +53,7 @@ static int fb_notifier_callback(struct n
}
}
mutex_unlock(&ld->ops_lock);
+ unlock_fb_info(evdata->info);
return 0;
}
diff -puN drivers/video/console/fbcon.c~revert-fbdev-fix-info-lock-deadlock-in-fbcon_event_notify drivers/video/console/fbcon.c
--- a/drivers/video/console/fbcon.c~revert-fbdev-fix-info-lock-deadlock-in-fbcon_event_notify
+++ a/drivers/video/console/fbcon.c
@@ -2263,12 +2263,9 @@ static void fbcon_generic_blank(struct v
}
- if (!lock_fb_info(info))
- return;
event.info = info;
event.data = ␣
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)
@@ -2959,6 +2956,8 @@ 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)
@@ -2986,6 +2985,8 @@ 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);
@@ -3026,8 +3027,11 @@ 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++) {
@@ -3148,23 +3152,53 @@ 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:
@@ -3183,14 +3217,29 @@ 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:
diff -puN drivers/video/fbmem.c~revert-fbdev-fix-info-lock-deadlock-in-fbcon_event_notify drivers/video/fbmem.c
--- a/drivers/video/fbmem.c~revert-fbdev-fix-info-lock-deadlock-in-fbcon_event_notify
+++ a/drivers/video/fbmem.c
@@ -1097,11 +1097,8 @@ 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:
@@ -1118,11 +1115,8 @@ 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))
@@ -1527,10 +1521,7 @@ 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;
}
@@ -1564,12 +1555,8 @@ 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;
@@ -1603,8 +1590,6 @@ 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);
@@ -1613,7 +1598,6 @@ 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);
}
/**
@@ -1683,11 +1667,8 @@ 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;
_
Patches currently in -mm which might be from krzysztof.h1@xxxxx are
viafb-make-it-work-on-x86_64.patch
linux-next.patch
revert-fbdev-fix-info-lock-deadlock-in-fbcon_event_notify.patch
revert-fbdev-uninline-lock_fb_info.patch
revert-fbmem-fix-fb_info-lock-and-mm-mmap_sem-circular-locking-dependency.patch
revert-fbmem-dont-call-copy_from-to_user-with-mutex-held.patch
chipsfb-remove-redundant-assignment.patch
igafb-use-framebuffer_alloc-to-allocate-fb_info-struct.patch
offb-use-framebuffer_alloc-to-allocate-fb_info-struct.patch
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