On 2009-02-02 18:36, Andrey Borzenkov wrote:
> I hope you do not think I'm doing this on purpose? :)
LOL!
Don't worry, we'll be able to fix it before linux 3.0.0 (maybe).
>
> [ 241.668005] =======================================================
> [ 241.668044] [ INFO: possible circular locking dependency detected ]
> [ 241.668068] 2.6.29-rc3-1avb #17
> [ 241.668080] -------------------------------------------------------
> [ 241.668100] s2disk/4219 is trying to acquire lock:
> [ 241.668118] (&fb_info->lock){--..}, at: [<c02235e7>]
> fb_mmap+0x97/0x170
> [ 241.668188]
> [ 241.668190] but task is already holding lock:
> [ 241.668207] (&mm->mmap_sem){----}, at: [<c010639e>]
> sys_mmap2+0x8e/0xc0
> [ 241.668256]
> [ 241.668258] which lock already depends on the new lock.
> [ 241.668262]
> [ 241.668282]
> [ 241.668284] the existing dependency chain (in reverse order) is:
> [ 241.668305]
> [ 241.668307] -> #2 (&mm->mmap_sem){----}:
> [ 241.668331] [<c014520f>] __lock_acquire+0x129f/0x1930
> [ 241.668362] [<c01458fc>] lock_acquire+0x5c/0x80
> [ 241.668382] [<c0182117>] might_fault+0x77/0xa0
> [ 241.668413] [<c0209916>] copy_to_user+0x36/0x120
> [ 241.668439] [<c01a60f7>] filldir+0x97/0xe0
> [ 241.668482] [<c01de339>] sysfs_readdir+0x129/0x220
> [ 241.668508] [<c01a62a6>] vfs_readdir+0x86/0xa0
> [ 241.668529] [<c01a63e8>] sys_getdents+0x68/0xc0
> [ 241.668549] [<c010344a>] syscall_call+0x7/0xb
> [ 241.668570] [<ffffffff>] 0xffffffff
> [ 241.668650]
> [ 241.668653] -> #1 (sysfs_mutex){--..}:
> [ 241.668676] [<c014520f>] __lock_acquire+0x129f/0x1930
> [ 241.668698] [<c01458fc>] lock_acquire+0x5c/0x80
> [ 241.668718] [<c030820a>] mutex_lock_nested+0xba/0x2f0
> [ 241.668749] [<c01de6cc>] sysfs_addrm_start+0x2c/0xc0
> [ 241.668771] [<c01dec80>] create_dir+0x40/0x90
> [ 241.668792] [<c01decfb>] sysfs_create_dir+0x2b/0x50
> [ 241.668812] [<c02036bc>] kobject_add_internal+0xbc/0x1b0
> [ 241.668853] [<c0203881>] kobject_add_varg+0x31/0x50
> [ 241.668874] [<c02038fc>] kobject_add+0x2c/0x60
> [ 241.668895] [<c0273718>] device_add+0xa8/0x550
> [ 241.668938] [<c0273bd2>] device_register+0x12/0x20
> [ 241.668960] [<c0273c8b>] device_create_vargs+0xab/0xc0
> [ 241.668982] [<c0273cc8>] device_create+0x28/0x30
> [ 241.669003] [<c026cf3d>] register_con_driver+0xed/0x130
> [ 241.669027] [<c026e45b>] take_over_console+0x1b/0x50
> [ 241.669049] [<c02304dd>] fbcon_takeover+0x5d/0xb0
> [ 241.669081] [<c0231457>] fbcon_event_notify+0xb27/0xc20
> [ 241.669104] [<c030c683>] notifier_call_chain+0x53/0xa0
> [ 241.669138] [<c0138ab4>]
> __blocking_notifier_call_chain+0x44/0x60
> [ 241.669218] [<c0138aea>]
> blocking_notifier_call_chain+0x1a/0x20
> [ 241.669246] [<c0222f81>] fb_notifier_call_chain+0x11/0x20
> [ 241.669276] [<c0223f08>] register_framebuffer+0x168/0x220
> [ 241.669305] [<c0414ba2>] vesafb_probe+0x542/0x783
> [ 241.669347] [<c027687f>] platform_drv_probe+0xf/0x20
> [ 241.669378] [<c0275a97>] driver_probe_device+0x87/0x1b0
> [ 241.669404] [<c0275c58>] __device_attach+0x8/0x10
> [ 241.669429] [<c02750db>] bus_for_each_drv+0x5b/0x80
> [ 241.669460] [<c0275d06>] device_attach+0x76/0x80
> [ 241.669484] [<c0274ef7>] bus_attach_device+0x47/0x70
> [ 241.669511] [<c0273993>] device_add+0x323/0x550
> [ 241.669536] [<c0277255>] platform_device_add+0x175/0x1c0
> [ 241.669567] [<c0414e7d>] vesafb_init+0x9a/0x1ec
> [ 241.669592] [<c010111a>] do_one_initcall+0x2a/0x160
> [ 241.669619] [<c04004d5>] kernel_init+0x83/0xd5
> [ 241.669661] [<c0103a77>] kernel_thread_helper+0x7/0x10
> [ 241.669688] [<ffffffff>] 0xffffffff
> [ 241.669737]
> [ 241.669739] -> #0 (&fb_info->lock){--..}:
> [ 241.669770] [<c014537c>] __lock_acquire+0x140c/0x1930
> [ 241.669797] [<c01458fc>] lock_acquire+0x5c/0x80
> [ 241.669821] [<c030820a>] mutex_lock_nested+0xba/0x2f0
> [ 241.669847] [<c02235e7>] fb_mmap+0x97/0x170
> [ 241.669872] [<c0188c76>] mmap_region+0x1d6/0x530
> [ 241.669908] [<c01891a3>] do_mmap_pgoff+0x1d3/0x2f0
> [ 241.669934] [<c01063bd>] sys_mmap2+0xad/0xc0
> [ 241.669959] [<c0103371>] sysenter_do_call+0x12/0x31
> [ 241.669984] [<ffffffff>] 0xffffffff
> [ 241.670009]
> [ 241.670012] other info that might help us debug this:
> [ 241.670015]
> [ 241.670049] 1 lock held by s2disk/4219:
> [ 241.670065] #0: (&mm->mmap_sem){----}, at: [<c010639e>]
> sys_mmap2+0x8e/0xc0
> [ 241.670092]
> [ 241.670092] stack backtrace:
> [ 241.670092] Pid: 4219, comm: s2disk Not tainted 2.6.29-rc3-1avb #17
> [ 241.670092] Call Trace:
> [ 241.670092] [<c0306e38>] ? printk+0x18/0x20
> [ 241.670092] [<c0143b1f>] print_circular_bug_tail+0xcf/0xe0
> [ 241.670092] [<c014537c>] __lock_acquire+0x140c/0x1930
> [ 241.670092] [<c01487f0>] ? futex_wait+0x170/0x450
> [ 241.670092] [<c011826c>] ? try_to_wake_up+0x10c/0x120
> [ 241.670092] [<c0309d15>] ? _spin_unlock_irqrestore+0x35/0x60
> [ 241.670092] [<c0141105>] ? lock_release_holdtime+0x35/0x210
> [ 241.670092] [<c01458fc>] lock_acquire+0x5c/0x80
> [ 241.670092] [<c02235e7>] ? fb_mmap+0x97/0x170
> [ 241.670092] [<c030820a>] mutex_lock_nested+0xba/0x2f0
> [ 241.670092] [<c02235e7>] ? fb_mmap+0x97/0x170
> [ 241.670092] [<c02235e7>] ? fb_mmap+0x97/0x170
> [ 241.670092] [<c019542d>] ? kmem_cache_alloc+0xad/0x100
> [ 241.670092] [<c02235e7>] fb_mmap+0x97/0x170
> [ 241.670092] [<c0188c76>] mmap_region+0x1d6/0x530
> [ 241.670092] [<c0186cfd>] ? arch_get_unmapped_area_topdown+0x8d/0x170
> [ 241.670092] [<c01891a3>] do_mmap_pgoff+0x1d3/0x2f0
> [ 241.670092] [<c01063bd>] sys_mmap2+0xad/0xc0
> [ 241.670092] [<c0103371>] sysenter_do_call+0x12/0x31
> [ 244.217754] Syncing filesystems ... done.
> [ 244.228175] Freezing user space processes ... (elapsed 0.00 seconds)
> done.
OK, another patch. This one is a cumulative patch against the latest
Linus' git.
Thanks again!
-Andrea
---
fbmem: fix circular locking dependency between fb_info->lock and mm->mmap_sem
Avoid calling copy_from/to_user() with fb_info->lock mutex held in the
framebuffer's ioctl().
fb_mmap() is called under mm->mmap_sem (A) held, that also acquires
fb_info->lock (B); fb_ioctl() takes fb_info->lock (B) and does
copy_from/to_user() that might acquire mm->mmap_sem (A), causing a
deadlock.
Also fix other potential circular locking dependencies (always between
fb_info->lock and mm->mmap_sem) in fbcon that occur calling the blocking
fb_notifier_call_chain() with fb_info->lock held.
NOTE: it doesn't push down the fb_info->lock in each own driver's
specific fb_ioctl() implementation, so there are still some potential
deadlocks elsewhere.
CC: Andrey Borzenkov <arvidjaar@xxxxxxx>
Signed-off-by: Andrea Righi <righi.andrea@xxxxxxxxx>
---
drivers/video/backlight/backlight.c | 3 +
drivers/video/backlight/lcd.c | 3 +
drivers/video/console/fbcon.c | 73 +++++++++++++++++---
drivers/video/fbcmap.c | 20 ++++--
drivers/video/fbmem.c | 128 +++++++++++++++++------------------
include/linux/fb.h | 15 ++++
6 files changed, 160 insertions(+), 82 deletions(-)
diff --git a/drivers/video/backlight/backlight.c b/drivers/video/backlight/backlight.c
index 157057c..dd37cbc 100644
--- a/drivers/video/backlight/backlight.c
+++ b/drivers/video/backlight/backlight.c
@@ -35,6 +35,8 @@ static int fb_notifier_callback(struct notifier_block *self,
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 notifier_block *self,
backlight_update_status(bd);
}
mutex_unlock(&bd->ops_lock);
+ unlock_fb_info(evdata->info);
return 0;
}
diff --git a/drivers/video/backlight/lcd.c b/drivers/video/backlight/lcd.c
index b644947..0bb13df 100644
--- a/drivers/video/backlight/lcd.c
+++ b/drivers/video/backlight/lcd.c
@@ -40,6 +40,8 @@ static int fb_notifier_callback(struct notifier_block *self,
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 notifier_block *self,
}
}
mutex_unlock(&ld->ops_lock);
+ unlock_fb_info(evdata->info);
return 0;
}
diff --git a/drivers/video/console/fbcon.c b/drivers/video/console/fbcon.c
index 1657b96..2cd500a 100644
--- a/drivers/video/console/fbcon.c
+++ b/drivers/video/console/fbcon.c
@@ -2954,8 +2954,11 @@ static int fbcon_fb_unbind(int idx)
static int fbcon_fb_unregistered(struct fb_info *info)
{
- int i, idx = info->node;
+ 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)
con2fb_map[i] = -1;
@@ -2979,13 +2982,14 @@ static int fbcon_fb_unregistered(struct fb_info *info)
}
}
- if (!num_registered_fb)
- unregister_con_driver(&fb_con);
-
-
if (primary_device == idx)
primary_device = -1;
+ unlock_fb_info(info);
+
+ if (!num_registered_fb)
+ unregister_con_driver(&fb_con);
+
return 0;
}
@@ -3021,9 +3025,13 @@ static inline void fbcon_select_primary(struct fb_info *info)
static int fbcon_fb_registered(struct fb_info *info)
{
- int ret = 0, i, idx = info->node;
+ 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++) {
@@ -3124,7 +3132,7 @@ static void fbcon_get_requirement(struct fb_info *info,
}
}
-static int fbcon_event_notify(struct notifier_block *self,
+static int fbcon_event_notify(struct notifier_block *self,
unsigned long action, void *data)
{
struct fb_event *event = data;
@@ -3132,7 +3140,7 @@ static int fbcon_event_notify(struct notifier_block *self,
struct fb_videomode *mode;
struct fb_con2fbmap *con2fb;
struct fb_blit_caps *caps;
- int ret = 0;
+ int idx, ret = 0;
/*
* ignore all events except driver registration and deregistration
@@ -3144,23 +3152,54 @@ static int fbcon_event_notify(struct notifier_block *self,
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:
- ret = fbcon_fb_unbind(info->node);
+ 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:
ret = fbcon_fb_registered(info);
@@ -3178,17 +3217,31 @@ static int fbcon_event_notify(struct notifier_block *self,
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:
return ret;
}
diff --git a/drivers/video/fbcmap.c b/drivers/video/fbcmap.c
index 91b78e6..f53b9f1 100644
--- a/drivers/video/fbcmap.c
+++ b/drivers/video/fbcmap.c
@@ -250,10 +250,6 @@ int fb_set_user_cmap(struct fb_cmap_user *cmap, struct fb_info *info)
int rc, size = cmap->len * sizeof(u16);
struct fb_cmap umap;
- if (cmap->start < 0 || (!info->fbops->fb_setcolreg &&
- !info->fbops->fb_setcmap))
- return -EINVAL;
-
memset(&umap, 0, sizeof(struct fb_cmap));
rc = fb_alloc_cmap(&umap, cmap->len, cmap->transp != NULL);
if (rc)
@@ -262,11 +258,23 @@ int fb_set_user_cmap(struct fb_cmap_user *cmap, struct fb_info *info)
copy_from_user(umap.green, cmap->green, size) ||
copy_from_user(umap.blue, cmap->blue, size) ||
(cmap->transp && copy_from_user(umap.transp, cmap->transp, size))) {
- fb_dealloc_cmap(&umap);
- return -EFAULT;
+ rc = -EFAULT;
+ goto out;
}
umap.start = cmap->start;
+ if (!lock_fb_info(info)) {
+ rc = -ENODEV;
+ goto out;
+ }
+ if (cmap->start < 0 || (!info->fbops->fb_setcolreg &&
+ !info->fbops->fb_setcmap)) {
+ rc = -EINVAL;
+ goto out1;
+ }
rc = fb_set_cmap(&umap, info);
+out1:
+ unlock_fb_info(info);
+out:
fb_dealloc_cmap(&umap);
return rc;
}
diff --git a/drivers/video/fbmem.c b/drivers/video/fbmem.c
index 756efeb..5cdee72 100644
--- a/drivers/video/fbmem.c
+++ b/drivers/video/fbmem.c
@@ -1013,132 +1013,132 @@ static long do_fb_ioctl(struct fb_info *info, unsigned int cmd,
struct fb_var_screeninfo var;
struct fb_fix_screeninfo fix;
struct fb_con2fbmap con2fb;
+ struct fb_cmap cmap_from;
struct fb_cmap_user cmap;
struct fb_event event;
void __user *argp = (void __user *)arg;
long ret = 0;
- fb = info->fbops;
- if (!fb)
- return -ENODEV;
-
switch (cmd) {
case FBIOGET_VSCREENINFO:
- ret = copy_to_user(argp, &info->var,
- sizeof(var)) ? -EFAULT : 0;
+ if (!lock_fb_info(info))
+ return -ENODEV;
+ var = info->var;
+ unlock_fb_info(info);
+
+ ret = copy_to_user(argp, &var, sizeof(var)) ? -EFAULT : 0;
break;
case FBIOPUT_VSCREENINFO:
- if (copy_from_user(&var, argp, sizeof(var))) {
- ret = -EFAULT;
- break;
- }
+ if (copy_from_user(&var, argp, sizeof(var)))
+ return -EFAULT;
+ if (!lock_fb_info(info))
+ return -ENODEV;
acquire_console_sem();
info->flags |= FBINFO_MISC_USEREVENT;
ret = fb_set_var(info, &var);
info->flags &= ~FBINFO_MISC_USEREVENT;
release_console_sem();
- if (ret == 0 && copy_to_user(argp, &var, sizeof(var)))
+ unlock_fb_info(info);
+ if (!ret && copy_to_user(argp, &var, sizeof(var)))
ret = -EFAULT;
break;
case FBIOGET_FSCREENINFO:
- ret = copy_to_user(argp, &info->fix,
- sizeof(fix)) ? -EFAULT : 0;
+ if (!lock_fb_info(info))
+ return -ENODEV;
+ fix = info->fix;
+ unlock_fb_info(info);
+
+ ret = copy_to_user(argp, &fix, sizeof(fix)) ? -EFAULT : 0;
break;
case FBIOPUTCMAP:
if (copy_from_user(&cmap, argp, sizeof(cmap)))
- ret = -EFAULT;
- else
- ret = fb_set_user_cmap(&cmap, info);
+ return -EFAULT;
+ ret = fb_set_user_cmap(&cmap, info);
break;
case FBIOGETCMAP:
if (copy_from_user(&cmap, argp, sizeof(cmap)))
- ret = -EFAULT;
- else
- ret = fb_cmap_to_user(&info->cmap, &cmap);
+ return -EFAULT;
+ if (!lock_fb_info(info))
+ return -ENODEV;
+ cmap_from = info->cmap;
+ unlock_fb_info(info);
+ ret = fb_cmap_to_user(&cmap_from, &cmap);
break;
case FBIOPAN_DISPLAY:
- if (copy_from_user(&var, argp, sizeof(var))) {
- ret = -EFAULT;
- break;
- }
+ if (copy_from_user(&var, argp, sizeof(var)))
+ return -EFAULT;
+ if (!lock_fb_info(info))
+ return -ENODEV;
acquire_console_sem();
ret = fb_pan_display(info, &var);
release_console_sem();
+ unlock_fb_info(info);
if (ret == 0 && copy_to_user(argp, &var, sizeof(var)))
- ret = -EFAULT;
+ return -EFAULT;
break;
case FBIO_CURSOR:
ret = -EINVAL;
break;
case FBIOGET_CON2FBMAP:
if (copy_from_user(&con2fb, argp, sizeof(con2fb)))
- ret = -EFAULT;
- else if (con2fb.console < 1 || con2fb.console > MAX_NR_CONSOLES)
- ret = -EINVAL;
- else {
- con2fb.framebuffer = -1;
- event.info = info;
- event.data = &con2fb;
- fb_notifier_call_chain(FB_EVENT_GET_CONSOLE_MAP,
- &event);
- ret = copy_to_user(argp, &con2fb,
- sizeof(con2fb)) ? -EFAULT : 0;
- }
+ return -EFAULT;
+ if (con2fb.console < 1 || con2fb.console > MAX_NR_CONSOLES)
+ return -EINVAL;
+ con2fb.framebuffer = -1;
+ event.data = &con2fb;
+ event.info = info;
+ fb_notifier_call_chain(FB_EVENT_GET_CONSOLE_MAP, &event);
+
+ ret = copy_to_user(argp, &con2fb, sizeof(con2fb)) ? -EFAULT : 0;
break;
case FBIOPUT_CON2FBMAP:
- if (copy_from_user(&con2fb, argp, sizeof(con2fb))) {
- ret = -EFAULT;
- break;
- }
- if (con2fb.console < 1 || con2fb.console > MAX_NR_CONSOLES) {
- ret = -EINVAL;
- break;
- }
- if (con2fb.framebuffer < 0 || con2fb.framebuffer >= FB_MAX) {
- ret = -EINVAL;
- break;
- }
+ if (copy_from_user(&con2fb, argp, sizeof(con2fb)))
+ return -EFAULT;
+ if (con2fb.console < 1 || con2fb.console > MAX_NR_CONSOLES)
+ return -EINVAL;
+ if (con2fb.framebuffer < 0 || con2fb.framebuffer >= FB_MAX)
+ return -EINVAL;
if (!registered_fb[con2fb.framebuffer])
request_module("fb%d", con2fb.framebuffer);
if (!registered_fb[con2fb.framebuffer]) {
ret = -EINVAL;
break;
}
- event.info = info;
event.data = &con2fb;
+ event.info = info;
ret = fb_notifier_call_chain(FB_EVENT_SET_CONSOLE_MAP,
&event);
break;
case FBIOBLANK:
+ if (!lock_fb_info(info))
+ return -ENODEV;
acquire_console_sem();
info->flags |= FBINFO_MISC_USEREVENT;
ret = fb_blank(info, arg);
info->flags &= ~FBINFO_MISC_USEREVENT;
release_console_sem();
- break;;
+ unlock_fb_info(info);
+ break;
default:
- if (fb->fb_ioctl == NULL)
- ret = -ENOTTY;
- else
+ if (!lock_fb_info(info))
+ return -ENODEV;
+ fb = info->fbops;
+ if (fb->fb_ioctl)
ret = fb->fb_ioctl(info, cmd, arg);
+ else
+ ret = -ENOTTY;
+ unlock_fb_info(info);
}
return ret;
}
static long fb_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
-__acquires(&info->lock)
-__releases(&info->lock)
{
struct inode *inode = file->f_path.dentry->d_inode;
int fbidx = iminor(inode);
- struct fb_info *info;
- long ret;
+ struct fb_info *info = registered_fb[fbidx];
- info = registered_fb[fbidx];
- mutex_lock(&info->lock);
- ret = do_fb_ioctl(info, cmd, arg);
- mutex_unlock(&info->lock);
- return ret;
+ return do_fb_ioctl(info, cmd, arg);
}
#ifdef CONFIG_COMPAT
@@ -1257,8 +1257,6 @@ static int fb_get_fscreeninfo(struct fb_info *info, unsigned int cmd,
static long fb_compat_ioctl(struct file *file, unsigned int cmd,
unsigned long arg)
-__acquires(&info->lock)
-__releases(&info->lock)
{
struct inode *inode = file->f_path.dentry->d_inode;
int fbidx = iminor(inode);
@@ -1266,7 +1264,6 @@ __releases(&info->lock)
struct fb_ops *fb = info->fbops;
long ret = -ENOIOCTLCMD;
- mutex_lock(&info->lock);
switch(cmd) {
case FBIOGET_VSCREENINFO:
case FBIOPUT_VSCREENINFO:
@@ -1292,7 +1289,6 @@ __releases(&info->lock)
ret = fb->fb_compat_ioctl(info, cmd, arg);
break;
}
- mutex_unlock(&info->lock);
return ret;
}
#endif
diff --git a/include/linux/fb.h b/include/linux/fb.h
index 818fe21..31527e1 100644
--- a/include/linux/fb.h
+++ b/include/linux/fb.h
@@ -960,6 +960,21 @@ extern struct fb_info *registered_fb[FB_MAX];
extern int num_registered_fb;
extern struct class *fb_class;
+static inline int lock_fb_info(struct fb_info *info)
+{
+ mutex_lock(&info->lock);
+ if (!info->fbops) {
+ mutex_unlock(&info->lock);
+ return 0;
+ }
+ return 1;
+}
+
+static inline void unlock_fb_info(struct fb_info *info)
+{
+ mutex_unlock(&info->lock);
+}
+
static inline void __fb_pad_aligned_buffer(u8 *dst, u32 d_pitch,
u8 *src, u32 s_pitch, u32 height)
{
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