Messages in this thread Patch in this message | | | From | Thiago Galesi <> | Subject | Re: [Linux-fbdev-devel] [PATCH] fb: Remove use of lock_kernel / unlock_kernel in fbmem | Date | Fri, 18 Apr 2008 21:54:43 -0300 |
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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@gmail.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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