From: Matt Mackall <mpm@selenic.com>
Date: Fri, 29 Jan 2010 08:50:36 +0000 (+1300)
Subject: random: drop weird m_time/a_time manipulation
X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=a996996dd75a9086b12d1cb4010f26e1748993f0;p=GitHub%2FLineageOS%2FG12%2Fandroid_kernel_amlogic_linux-4.9.git

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 8258982b49ec..3495d6486b71 100644
--- 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;
 }