[PATCH] fbdev: Fix return error of fb_write

Fix return code of fb_write():

If at least 1 byte was transferred to the device, return number of bytes,
otherwise:

    - return -EFBIG - if file offset is past the maximum allowable offset or
      size is greater than framebuffer length
    - return -ENOSPC - if size is greater than framebuffer length - offset

Signed-off-by: Antonino Daplas <adaplas@pol.net>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 10 insertions, 4 deletions

diff --git a/drivers/video/fbmem.c b/drivers/video/fbmem.c
index 8d8eadb64853..372aa1776827 100644
--- a/drivers/video/fbmem.c
+++ b/drivers/video/fbmem.c
@@ -674,13 +674,19 @@ fb_write(struct file *file, const char __user *buf, size_t count, loff_t *ppos)
                 total_size = info->fix.smem_len;
 
         if (p > total_size)
-                return 0;
+                return -EFBIG;
 
-        if (count >= total_size)
+        if (count > total_size) {
+                err = -EFBIG;
                 count = total_size;
+        }
+
+        if (count + p > total_size) {
+                if (!err)
+                        err = -ENOSPC;
 
-        if (count + p > total_size)
                 count = total_size - p;
+        }
 
         buffer = kmalloc((count > PAGE_SIZE) ? PAGE_SIZE : count,
                          GFP_KERNEL);
@@ -722,7 +728,7 @@ fb_write(struct file *file, const char __user *buf, size_t count, loff_t *ppos)
 
         kfree(buffer);
 
-        return (err) ? err : cnt;
+        return (cnt) ? cnt : err;
 }
 
 #ifdef CONFIG_KMOD