linux-kernel - [ 13/70] random: Adjust the number of loops when initializing

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Message-Id: <20120807032757.992864060@decadent.org.uk>
Date:	Tue, 07 Aug 2012 04:28:08 +0100
From:	Ben Hutchings <ben@...adent.org.uk>
To:	linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:	torvalds@...ux-foundation.org, akpm@...ux-foundation.org,
	alan@...rguk.ukuu.org.uk, "H. Peter Anvin" <hpa@...ux.intel.com>,
	"Theodore Tso" <tytso@....edu>
Subject: [ 13/70] random: Adjust the number of loops when initializing

3.2-stable review patch.  If anyone has any objections, please let me know.

------------------

From: "H. Peter Anvin" <hpa@...ux.intel.com>

commit 2dac8e54f988ab58525505d7ef982493374433c3 upstream.

When we are initializing using arch_get_random_long() we only need to
loop enough times to touch all the bytes in the buffer; using
poolwords for that does twice the number of operations necessary on a
64-bit machine, since in the random number generator code "word" means
32 bits.

Signed-off-by: H. Peter Anvin <hpa@...ux.intel.com>
Cc: "Theodore Ts'o" <tytso@....edu>
Link: http://lkml.kernel.org/r/1324589281-31931-1-git-send-email-tytso@mit.edu
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
 drivers/char/random.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/char/random.c b/drivers/char/random.c
index 3079477..9a2156d 100644
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -975,7 +975,7 @@ static void init_std_data(struct entropy_store *r)
 
 	now = ktime_get_real();
 	mix_pool_bytes(r, &now, sizeof(now));
-	for (i = r->poolinfo->poolwords; i; i--) {
+	for (i = r->poolinfo->POOLBYTES; i > 0; i -= sizeof flags) {
 		if (!arch_get_random_long(&flags))
 			break;
 		mix_pool_bytes(r, &flags, sizeof(flags));


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