fb: convert lock/unlock_kernel() into local fb mutex

Change lock_kernel()/unlock_kernel() to local fb mutex.  Each frame buffer
instance has its own mutex.

The one line try_to_load() function is unrolled to request_module() in two
places for readability.

[righi.andrea@gmail.com: fb: fix NULL pointer BUG dereference in fb_open()]
Signed-off-by: Krzysztof Helt <krzysztof.h1@wp.pl>
Signed-off-by: Andrea Righi <righi.andrea@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/drivers/video/fbmem.c b/drivers/video/fbmem.c
index 2a0f013dc37bb99aaab2b10989133f270085f56a..cd5f20da738a0cb4e579a046c2a352a58791ea86 100644 (file)
--- a/drivers/video/fbmem.c
+++ b/drivers/video/fbmem.c
@@ -1018,12 +1018,12 @@ fb_ioctl(struct file *file, unsigned int cmd,
        void __user *argp = (void __user *)arg;
        long ret = 0;
 
-       lock_kernel();
        info = registered_fb[fbidx];
+       mutex_lock(&info->lock);
        fb = info->fbops;
 
        if (!fb) {
-               unlock_kernel();
+               mutex_unlock(&info->lock);
                return -ENODEV;
        }
        switch (cmd) {
@@ -1126,7 +1126,7 @@ fb_ioctl(struct file *file, unsigned int cmd,
                else
                        ret = fb->fb_ioctl(info, cmd, arg);
        }
-       unlock_kernel();
+       mutex_unlock(&info->lock);
        return ret;
 }
 
@@ -1253,7 +1253,7 @@ fb_compat_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
        struct fb_ops *fb = info->fbops;
        long ret = -ENOIOCTLCMD;
 
-       lock_kernel();
+       mutex_lock(&info->lock);
        switch(cmd) {
        case FBIOGET_VSCREENINFO:
        case FBIOPUT_VSCREENINFO:
@@ -1279,7 +1279,7 @@ fb_compat_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
                        ret = fb->fb_compat_ioctl(info, cmd, arg);
                break;
        }
-       unlock_kernel();
+       mutex_unlock(&info->lock);
        return ret;
 }
 #endif
@@ -1301,13 +1301,13 @@ fb_mmap(struct file *file, struct vm_area_struct * vma)
                return -ENODEV;
        if (fb->fb_mmap) {
                int res;
-               lock_kernel();
+               mutex_lock(&info->lock);
                res = fb->fb_mmap(info, vma);
-               unlock_kernel();
+               mutex_unlock(&info->lock);
                return res;
        }
 
-       lock_kernel();
+       mutex_lock(&info->lock);
 
        /* frame buffer memory */
        start = info->fix.smem_start;
@@ -1316,13 +1316,13 @@ fb_mmap(struct file *file, struct vm_area_struct * vma)
                /* memory mapped io */
                off -= len;
                if (info->var.accel_flags) {
-                       unlock_kernel();
+                       mutex_unlock(&info->lock);
                        return -EINVAL;
                }
                start = info->fix.mmio_start;
                len = PAGE_ALIGN((start & ~PAGE_MASK) + info->fix.mmio_len);
        }
-       unlock_kernel();
+       mutex_unlock(&info->lock);
        start &= PAGE_MASK;
        if ((vma->vm_end - vma->vm_start + off) > len)
                return -EINVAL;
@@ -1346,13 +1346,13 @@ fb_open(struct inode *inode, struct file *file)
 
        if (fbidx >= FB_MAX)
                return -ENODEV;
-       lock_kernel();
-       if (!(info = registered_fb[fbidx]))
+       info = registered_fb[fbidx];
+       if (!info)
                request_module("fb%d", fbidx);
-       if (!(info = registered_fb[fbidx])) {
-               res = -ENODEV;
-               goto out;
-       }
+       info = registered_fb[fbidx];
+       if (!info)
+               return -ENODEV;
+       mutex_lock(&info->lock);
        if (!try_module_get(info->fbops->owner)) {
                res = -ENODEV;
                goto out;
@@ -1368,7 +1368,7 @@ fb_open(struct inode *inode, struct file *file)
                fb_deferred_io_open(info, inode, file);
 #endif
 out:
-       unlock_kernel();
+       mutex_unlock(&info->lock);
        return res;
 }
 
@@ -1377,11 +1377,11 @@ fb_release(struct inode *inode, struct file *file)
 {
        struct fb_info * const info = file->private_data;
 
-       lock_kernel();
+       mutex_lock(&info->lock);
        if (info->fbops->fb_release)
                info->fbops->fb_release(info,1);
        module_put(info->fbops->owner);
-       unlock_kernel();
+       mutex_unlock(&info->lock);
        return 0;
 }
 
@@ -1460,6 +1460,7 @@ register_framebuffer(struct fb_info *fb_info)
                if (!registered_fb[i])
                        break;
        fb_info->node = i;
+       mutex_init(&fb_info->lock);
 
        fb_info->dev = device_create(fb_class, fb_info->device,
                                     MKDEV(FB_MAJOR, i), NULL, "fb%d", i);

diff --git a/include/linux/fb.h b/include/linux/fb.h
index 531ccd5f5960b0fe5818fdb768d3beb6bd3f3ea7..75a81eaf34309c43ba4da319babecd5e3bd00ca0 100644 (file)
--- a/include/linux/fb.h
+++ b/include/linux/fb.h
@@ -808,6 +808,7 @@ struct fb_tile_ops {
 struct fb_info {
        int node;
        int flags;
+       struct mutex lock;              /* Lock for open/release/ioctl funcs */
        struct fb_var_screeninfo var;   /* Current var */
        struct fb_fix_screeninfo fix;   /* Current fix */
        struct fb_monspecs monspecs;    /* Current Monitor specs */