random: delete code to pull data into pools

There is no pool that pulls, so it was just dead code.
Signed-off-by: Andy Lutomirski <luto@kernel.org>
Link: https://lore.kernel.org/r/4a05fe0c7a5c831389ef4aea51d24528ac8682c7.1577088521.git.luto@kernel.orgSigned-off-by: Theodore Ts'o <tytso@mit.edu>

drivers/char/random.c

@@ -528,10 +528,8 @@ 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;
@@ -1347,41 +1345,6 @@ 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.
@@ -1545,7 +1508,6 @@ static ssize_t extract_entropy(struct entropy_store *r, void *buf,
 			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);
@@ -1554,7 +1516,6 @@ static ssize_t extract_entropy(struct entropy_store *r, void *buf,
 	}
 
 	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);
@@ -1826,7 +1787,6 @@ static void __init init_std_data(struct entropy_store *r)
 	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) &&