linux-kernel - [PATCH 3/3] random: only update the last_pulled time if we actually transferred entropy

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Message-Id: <1402457420-2527-4-git-send-email-tytso@mit.edu>
Date:	Tue, 10 Jun 2014 23:30:20 -0400
From:	Theodore Ts'o <tytso@....edu>
To:	linux-kernel@...r.kernel.org
Cc:	Theodore Ts'o <tytso@....edu>, George Spelvin <linux@...izon.com>
Subject: [PATCH 3/3] random: only update the last_pulled time if we actually transferred entropy

In xfer_secondary_pull(), check to make sure we need to pull from the
secondary pool before checking and potentially updating the
last_pulled time.

Signed-off-by: Theodore Ts'o <tytso@....edu>
Cc: George Spelvin <linux@...izon.com>
---
 drivers/char/random.c | 11 +++++++----
 1 file changed, 7 insertions(+), 4 deletions(-)

diff --git a/drivers/char/random.c b/drivers/char/random.c
index 97f390b..4bb6e37 100644
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -919,6 +919,11 @@ static ssize_t extract_entropy(struct entropy_store *r, void *buf,
 static void _xfer_secondary_pool(struct entropy_store *r, size_t nbytes);
 static void xfer_secondary_pool(struct entropy_store *r, size_t nbytes)
 {
+	if (!r->pull ||
+	    r->entropy_count >= (nbytes << (ENTROPY_SHIFT + 3)) ||
+	    r->entropy_count > r->poolinfo->poolfracbits)
+		return;
+
 	if (r->limit == 0 && random_min_urandom_seed) {
 		unsigned long now = jiffies;
 
@@ -927,10 +932,8 @@ static void xfer_secondary_pool(struct entropy_store *r, size_t nbytes)
 			return;
 		r->last_pulled = now;
 	}
-	if (r->pull &&
-	    r->entropy_count < (nbytes << (ENTROPY_SHIFT + 3)) &&
-	    r->entropy_count < r->poolinfo->poolfracbits)
-		_xfer_secondary_pool(r, nbytes);
+
+	_xfer_secondary_pool(r, nbytes);
 }
 
 static void _xfer_secondary_pool(struct entropy_store *r, size_t nbytes)
-- 
2.0.0

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