Merge remote-tracking branch 'torvalds/master' into perf/core

[linux-2.6-microblaze.git] / drivers / char / mem.c

diff --git a/drivers/char/mem.c b/drivers/char/mem.c
index abd4ffd..94c2b55 100644 (file)
--- a/drivers/char/mem.c
+++ b/drivers/char/mem.c
@@ -726,6 +726,33 @@ static ssize_t read_iter_zero(struct kiocb *iocb, struct iov_iter *iter)
        return written;
 }
 
+static ssize_t read_zero(struct file *file, char __user *buf,
+                        size_t count, loff_t *ppos)
+{
+       size_t cleared = 0;
+
+       while (count) {
+               size_t chunk = min_t(size_t, count, PAGE_SIZE);
+               size_t left;
+
+               left = clear_user(buf + cleared, chunk);
+               if (unlikely(left)) {
+                       cleared += (chunk - left);
+                       if (!cleared)
+                               return -EFAULT;
+                       break;
+               }
+               cleared += chunk;
+               count -= chunk;
+
+               if (signal_pending(current))
+                       break;
+               cond_resched();
+       }
+
+       return cleared;
+}
+
 static int mmap_zero(struct file *file, struct vm_area_struct *vma)
 {
 #ifndef CONFIG_MMU
@@ -921,6 +948,7 @@ static const struct file_operations zero_fops = {
        .llseek         = zero_lseek,
        .write          = write_zero,
        .read_iter      = read_iter_zero,
+       .read           = read_zero,
        .write_iter     = write_iter_zero,
        .mmap           = mmap_zero,
        .get_unmapped_area = get_unmapped_area_zero,