linux-kernel - [PATCH 5.4 015/240] random: delete code to pull data into pools

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Date:   Mon, 20 Jun 2022 14:48:36 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Andy Lutomirski <luto@...nel.org>,
        Theodore Tso <tytso@....edu>,
        "Jason A. Donenfeld" <Jason@...c4.com>
Subject: [PATCH 5.4 015/240] random: delete code to pull data into pools

From: Andy Lutomirski <luto@...nel.org>

commit 84df7cdfbb215a34657b39f4257dab739efa2df9 upstream.

There is no pool that pulls, so it was just dead code.

Signed-off-by: Andy Lutomirski <luto@...nel.org>
Link: https://lore.kernel.org/r/4a05fe0c7a5c831389ef4aea51d24528ac8682c7.1577088521.git.luto@kernel.org
Signed-off-by: Theodore Ts'o <tytso@....edu>
Signed-off-by: Jason A. Donenfeld <Jason@...c4.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 drivers/char/random.c |   40 ----------------------------------------
 1 file changed, 40 deletions(-)

--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -529,10 +529,8 @@ struct entropy_store {
 	const struct poolinfo *poolinfo;
 	__u32 *pool;
 	const char *name;
-	struct entropy_store *pull;
 
 	/* read-write data: */
-	unsigned long last_pulled;
 	spinlock_t lock;
 	unsigned short add_ptr;
 	unsigned short input_rotate;
@@ -1368,41 +1366,6 @@ EXPORT_SYMBOL_GPL(add_disk_randomness);
  *********************************************************************/
 
 /*
- * This utility inline function is responsible for transferring entropy
- * from the primary pool to the secondary extraction pool. We make
- * sure we pull enough for a 'catastrophic reseed'.
- */
-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;
-
-	_xfer_secondary_pool(r, nbytes);
-}
-
-static void _xfer_secondary_pool(struct entropy_store *r, size_t nbytes)
-{
-	__u32	tmp[OUTPUT_POOL_WORDS];
-
-	int bytes = nbytes;
-
-	/* pull at least as much as a wakeup */
-	bytes = max_t(int, bytes, random_read_wakeup_bits / 8);
-	/* but never more than the buffer size */
-	bytes = min_t(int, bytes, sizeof(tmp));
-
-	trace_xfer_secondary_pool(r->name, bytes * 8, nbytes * 8,
-				  ENTROPY_BITS(r), ENTROPY_BITS(r->pull));
-	bytes = extract_entropy(r->pull, tmp, bytes,
-				random_read_wakeup_bits / 8, 0);
-	mix_pool_bytes(r, tmp, bytes);
-	credit_entropy_bits(r, bytes*8);
-}
-
-/*
  * This function decides how many bytes to actually take from the
  * given pool, and also debits the entropy count accordingly.
  */
@@ -1565,7 +1528,6 @@ static ssize_t extract_entropy(struct en
 			spin_unlock_irqrestore(&r->lock, flags);
 			trace_extract_entropy(r->name, EXTRACT_SIZE,
 					      ENTROPY_BITS(r), _RET_IP_);
-			xfer_secondary_pool(r, EXTRACT_SIZE);
 			extract_buf(r, tmp);
 			spin_lock_irqsave(&r->lock, flags);
 			memcpy(r->last_data, tmp, EXTRACT_SIZE);
@@ -1574,7 +1536,6 @@ static ssize_t extract_entropy(struct en
 	}
 
 	trace_extract_entropy(r->name, nbytes, ENTROPY_BITS(r), _RET_IP_);
-	xfer_secondary_pool(r, nbytes);
 	nbytes = account(r, nbytes, min, reserved);
 
 	return _extract_entropy(r, buf, nbytes, fips_enabled);
@@ -1846,7 +1807,6 @@ static void __init init_std_data(struct
 	ktime_t now = ktime_get_real();
 	unsigned long rv;
 
-	r->last_pulled = jiffies;
 	mix_pool_bytes(r, &now, sizeof(now));
 	for (i = r->poolinfo->poolbytes; i > 0; i -= sizeof(rv)) {
 		if (!arch_get_random_seed_long(&rv) &&