[PATCH] fbdev: Fix return code of fb_read and fb_write

Make fb_read() and fb_write() return 0 (EOF) instead of -ENOSPC if reading at
or past the end of the framebuffer.  This fixes user space apps hanging if
info->fix.smem_len == 0.

Whitespace changes.

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, 20 insertions, 12 deletions

diff --git a/drivers/video/fbmem.c b/drivers/video/fbmem.c
index 10dfdf035264..83e259413115 100644
--- a/drivers/video/fbmem.c
+++ b/drivers/video/fbmem.c
@@ -589,17 +589,19 @@ fb_read(struct file *file, char __user *buf, size_t count, loff_t *ppos)
                 return info->fbops->fb_read(file, buf, count, ppos);
         
         total_size = info->screen_size;
+
         if (total_size == 0)
                 total_size = info->fix.smem_len;
 
         if (p >= total_size)
-            return 0;
+                return 0;
+
         if (count >= total_size)
-            count = total_size;
+                count = total_size;
+
         if (count + p > total_size)
                 count = total_size - p;
 
-        cnt = 0;
         buffer = kmalloc((count > PAGE_SIZE) ? PAGE_SIZE : count,
                          GFP_KERNEL);
         if (!buffer)
@@ -636,6 +638,7 @@ fb_read(struct file *file, char __user *buf, size_t count, loff_t *ppos)
         }
 
         kfree(buffer);
+
         return (err) ? err : cnt;
 }
 
@@ -648,7 +651,7 @@ fb_write(struct file *file, const char __user *buf, size_t count, loff_t *ppos)
         struct fb_info *info = registered_fb[fbidx];
         u32 *buffer, *src;
         u32 __iomem *dst;
-        int c, i, cnt = 0, err;
+        int c, i, cnt = 0, err = 0;
         unsigned long total_size;
 
         if (!info || !info->screen_base)
@@ -661,19 +664,19 @@ fb_write(struct file *file, const char __user *buf, size_t count, loff_t *ppos)
                 return info->fbops->fb_write(file, buf, count, ppos);
         
         total_size = info->screen_size;
+
         if (total_size == 0)
                 total_size = info->fix.smem_len;
 
         if (p > total_size)
-            return -ENOSPC;
+                return 0;
+
         if (count >= total_size)
-            count = total_size;
-        err = 0;
-        if (count + p > total_size) {
-            count = total_size - p;
-            err = -ENOSPC;
-        }
-        cnt = 0;
+                count = total_size;
+
+        if (count + p > total_size)
+                count = total_size - p;
+
         buffer = kmalloc((count > PAGE_SIZE) ? PAGE_SIZE : count,
                          GFP_KERNEL);
         if (!buffer)
@@ -687,12 +690,15 @@ fb_write(struct file *file, const char __user *buf, size_t count, loff_t *ppos)
         while (count) {
                 c = (count > PAGE_SIZE) ? PAGE_SIZE : count;
                 src = buffer;
+
                 if (copy_from_user(src, buf, c)) {
                         err = -EFAULT;
                         break;
                 }
+
                 for (i = c >> 2; i--; )
                         fb_writel(*src++, dst++);
+
                 if (c & 3) {
                         u8 *src8 = (u8 *) src;
                         u8 __iomem *dst8 = (u8 __iomem *) dst;
@@ -702,11 +708,13 @@ fb_write(struct file *file, const char __user *buf, size_t count, loff_t *ppos)
 
                         dst = (u32 __iomem *) dst8;
                 }
+
                 *ppos += c;
                 buf += c;
                 cnt += c;
                 count -= c;
         }
+
         kfree(buffer);
 
         return (err) ? err : cnt;