linux-kernel - Fix add_timer_randomness throttling

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Message-ID: <20150204140029.GA2949@lst.de>
Date:	Wed, 4 Feb 2015 15:00:29 +0100
From:	Torsten Duwe <duwe@....de>
To:	Theodore Ts'o <tytso@....edu>
Cc:	"H. Peter Anvin" <hpa@...ux.intel.com>,
	lkml <linux-kernel@...r.kernel.org>
Subject: Fix add_timer_randomness throttling

Hi Ted,

review of a backport of a283b5c459784f97 suggests to me that it has one
replacement too much: in add_timer_randomness, entropy_count is compared
to trickle_thresh, which are _both_ scaled up by ENTROPY_SHIFT. I'd therefore
revert that hunk.

Signed-off-by: Torsten Duwe <duwe@...e.de>


@@ -674,7 +697,7 @@ static void add_timer_randomness(struct timer_rand_state *state, unsigned num)
 
 	preempt_disable();
 	/* if over the trickle threshold, use only 1 in 4096 samples */
-	if (ENTROPY_BITS(&input_pool) > trickle_thresh &&
+	if (input_pool.entropy_count > trickle_thresh &&
 	    ((__this_cpu_inc_return(trickle_count) - 1) & 0xfff))
 		goto out;
 

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