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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Eric Dumazet <edumazet@google.com>,
        Herbert Xu <herbert@gondor.apana.org.au>,
        "David S. Miller" <davem@davemloft.net>,
        Ben Hutchings <ben.hutchings@codethink.co.uk>
Subject: [PATCH 4.4 08/34] rhashtable: add schedule points
Date:   Thu,  7 Feb 2019 12:41:50 +0100
Message-Id: <20190207113025.890542584@linuxfoundation.org>
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4.4-stable review patch.  If anyone has any objections, please let me know.

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

From: Eric Dumazet <edumazet@google.com>

commit ae6da1f503abb5a5081f9f6c4a6881de97830f3e upstream.

Rehashing and destroying large hash table takes a lot of time,
and happens in process context. It is safe to add cond_resched()
in rhashtable_rehash_table() and rhashtable_free_and_destroy()

Signed-off-by: Eric Dumazet <edumazet@google.com>
Acked-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Ben Hutchings <ben.hutchings@codethink.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 lib/rhashtable.c |    5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

--- a/lib/rhashtable.c
+++ b/lib/rhashtable.c
@@ -250,8 +250,10 @@ static int rhashtable_rehash_table(struc
 	if (!new_tbl)
 		return 0;
 
-	for (old_hash = 0; old_hash < old_tbl->size; old_hash++)
+	for (old_hash = 0; old_hash < old_tbl->size; old_hash++) {
 		rhashtable_rehash_chain(ht, old_hash);
+		cond_resched();
+	}
 
 	/* Publish the new table pointer. */
 	rcu_assign_pointer(ht->tbl, new_tbl);
@@ -842,6 +844,7 @@ void rhashtable_free_and_destroy(struct
 		for (i = 0; i < tbl->size; i++) {
 			struct rhash_head *pos, *next;
 
+			cond_resched();
 			for (pos = rht_dereference(tbl->buckets[i], ht),
 			     next = !rht_is_a_nulls(pos) ?
 					rht_dereference(pos->next, ht) : NULL;