random: drop weird m_time/a_time manipulation

No other driver does anything remotely like this that I know of except
for the tty drivers, and I can't see any reason for random/urandom to do
it. In fact, it's a (trivial, harmless) timing information leak. And
obviously, it generates power- and flash-cycle wasting I/O, especially
if combined with something like hwrngd. Also, it breaks ubifs's
expectations.

Signed-off-by: Matt Mackall <mpm@selenic.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

diff --git a/drivers/char/random.c b/drivers/char/random.c
index 8258982..3495d64 100644 (file)
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -1051,12 +1051,6 @@ random_read(struct file *file, char __user *buf, size_t nbytes, loff_t *ppos)
                                /* like a named pipe */
        }
 
-       /*
-        * If we gave the user some bytes, update the access time.
-        */
-       if (count)
-               file_accessed(file);
-
        return (count ? count : retval);
 }
 
@@ -1116,8 +1110,6 @@ static ssize_t random_write(struct file *file, const char __user *buffer,
        if (ret)
                return ret;
 
-       inode->i_mtime = current_fs_time(inode->i_sb);
-       mark_inode_dirty(inode);
        return (ssize_t)count;
 }