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Date: Fri, 18 Apr 2008 21:54:43 -0300
From: Thiago Galesi <thiagogalesi@...il.com>
To: Andrew Morton <akpm@...ux-foundation.org>
Cc: linux-kernel@...r.kernel.org,
linux-fbdev-devel@...ts.sourceforge.net, dilinger@...ued.net
Subject: Re: [Linux-fbdev-devel] [PATCH] fb: Remove use of lock_kernel / unlock_kernel in fbmem
Hello
>Just a minor nit; in general, I'd think you would want to completely
>initialize the structure (including calling mutex_init) before
>registering the structure with the rest of the system (in this case,
>with registered_fb and *_call_notifier_chain). Initializing after
>registration is just asking for a race conditions.
This is better??
---
This patch removes lock_kernel(), unlock_kernel() usage in fbmem.c and replaces it with a mutex
Signed-off-by: Thiago Galesi <thiagogalesi@...il.com>
---
Index: linux-2.6.23.1/drivers/video/fbmem.c
===================================================================
--- linux-2.6.23.1.orig/drivers/video/fbmem.c 2008-04-16 18:52:32.000000000 -0300
+++ linux-2.6.23.1/drivers/video/fbmem.c 2008-04-18 19:25:53.000000000 -0300
@@ -987,7 +987,7 @@
}
static int
-fb_ioctl(struct inode *inode, struct file *file, unsigned int cmd,
+__fb_ioctl(struct inode *inode, struct file *file, unsigned int cmd,
unsigned long arg)
{
int fbidx = iminor(inode);
@@ -1085,6 +1085,28 @@
}
}
+static int
+fb_ioctl(struct inode *inode, struct file *file, unsigned int cmd,
+ unsigned long arg)
+{
+ int fbidx = iminor(inode);
+ struct fb_info *info = registered_fb[fbidx];
+ int ret;
+
+ mutex_lock(&info->hwlock);
+ ret = __fb_ioctl(inode, file, cmd, arg);
+ mutex_unlock(&info->hwlock);
+ return ret;
+}
+
+static long
+fb_unlocked_ioctl(struct file *file, unsigned int cmd,
+ unsigned long arg)
+{
+ struct inode *inode = file->f_path.dentry->d_inode;
+ return fb_ioctl(inode, file, cmd, arg);
+}
+
#ifdef CONFIG_COMPAT
struct fb_fix_screeninfo32 {
char id[16];
@@ -1136,7 +1158,7 @@
put_user(compat_ptr(data), &cmap->transp))
return -EFAULT;
- err = fb_ioctl(inode, file, cmd, (unsigned long) cmap);
+ err = __fb_ioctl(inode, file, cmd, (unsigned long) cmap);
if (!err) {
if (copy_in_user(&cmap32->start,
@@ -1190,7 +1212,7 @@
old_fs = get_fs();
set_fs(KERNEL_DS);
- err = fb_ioctl(inode, file, cmd, (unsigned long) &fix);
+ err = __fb_ioctl(inode, file, cmd, (unsigned long) &fix);
set_fs(old_fs);
if (!err)
@@ -1208,7 +1230,7 @@
struct fb_ops *fb = info->fbops;
long ret = -ENOIOCTLCMD;
- lock_kernel();
+ mutex_lock(&info->hwlock);
switch(cmd) {
case FBIOGET_VSCREENINFO:
case FBIOPUT_VSCREENINFO:
@@ -1217,7 +1239,7 @@
case FBIOPUT_CON2FBMAP:
arg = (unsigned long) compat_ptr(arg);
case FBIOBLANK:
- ret = fb_ioctl(inode, file, cmd, arg);
+ ret = __fb_ioctl(inode, file, cmd, arg);
break;
case FBIOGET_FSCREENINFO:
@@ -1234,7 +1256,7 @@
ret = fb->fb_compat_ioctl(info, cmd, arg);
break;
}
- unlock_kernel();
+ mutex_unlock(&info->hwlock);
return ret;
}
#endif
@@ -1256,13 +1278,13 @@
return -ENODEV;
if (fb->fb_mmap) {
int res;
- lock_kernel();
+ mutex_lock(&info->hwlock);
res = fb->fb_mmap(info, vma);
- unlock_kernel();
+ mutex_unlock(&info->hwlock);
return res;
}
- lock_kernel();
+ mutex_lock(&info->hwlock);
/* frame buffer memory */
start = info->fix.smem_start;
@@ -1271,13 +1293,13 @@
/* memory mapped io */
off -= len;
if (info->var.accel_flags) {
- unlock_kernel();
+ mutex_unlock(&info->hwlock);
return -EINVAL;
}
start = info->fix.mmio_start;
len = PAGE_ALIGN((start & ~PAGE_MASK) + info->fix.mmio_len);
}
- unlock_kernel();
+ mutex_unlock(&info->hwlock);
start &= PAGE_MASK;
if ((vma->vm_end - vma->vm_start + off) > len)
return -EINVAL;
@@ -1323,25 +1345,25 @@
{
struct fb_info * const info = file->private_data;
- lock_kernel();
+ mutex_lock(&info->hwlock);
if (info->fbops->fb_release)
info->fbops->fb_release(info,1);
module_put(info->fbops->owner);
- unlock_kernel();
+ mutex_unlock(&info->hwlock);
return 0;
}
static const struct file_operations fb_fops = {
- .owner = THIS_MODULE,
- .read = fb_read,
- .write = fb_write,
- .ioctl = fb_ioctl,
+ .owner = THIS_MODULE,
+ .read = fb_read,
+ .write = fb_write,
+ .unlocked_ioctl = fb_unlocked_ioctl,
#ifdef CONFIG_COMPAT
- .compat_ioctl = fb_compat_ioctl,
+ .compat_ioctl = fb_compat_ioctl,
#endif
- .mmap = fb_mmap,
- .open = fb_open,
- .release = fb_release,
+ .mmap = fb_mmap,
+ .open = fb_open,
+ .release = fb_release,
#ifdef HAVE_ARCH_FB_UNMAPPED_AREA
.get_unmapped_area = get_fb_unmapped_area,
#endif
@@ -1377,6 +1399,7 @@
break;
fb_info->node = i;
+ mutex_init(&fb_info->hwlock);
fb_info->dev = device_create(fb_class, fb_info->device,
MKDEV(FB_MAJOR, i), "fb%d", i);
if (IS_ERR(fb_info->dev)) {
@@ -1413,6 +1436,7 @@
event.info = fb_info;
fb_notifier_call_chain(FB_EVENT_FB_REGISTERED, &event);
+
return 0;
}
@@ -1464,6 +1488,7 @@
device_destroy(fb_class, MKDEV(FB_MAJOR, i));
event.info = fb_info;
fb_notifier_call_chain(FB_EVENT_FB_UNREGISTERED, &event);
+ mutex_destroy(&fb_info.hwlock);
done:
return ret;
}
Index: linux-2.6.23.1/include/linux/fb.h
===================================================================
--- linux-2.6.23.1.orig/include/linux/fb.h 2008-04-16 18:52:32.000000000 -0300
+++ linux-2.6.23.1/include/linux/fb.h 2008-04-16 18:53:22.000000000 -0300
@@ -802,6 +802,7 @@
struct list_head modelist; /* mode list */
struct fb_videomode *mode; /* current mode */
+ struct mutex hwlock; /* mutex for protecting hw ops */
#ifdef CONFIG_FB_BACKLIGHT
/* assigned backlight device */
/* set before framebuffer registration,
--
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