linux-kernel - [PATCH 1/7] rhashtable: silence RCU warning in rhashtable

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Date:   Mon, 18 Jun 2018 12:52:50 +1000
From:   NeilBrown <neilb@...e.com>
To:     Thomas Graf <tgraf@...g.ch>,
        Herbert Xu <herbert@...dor.apana.org.au>,
        David Miller <davem@...emloft.net>
Cc:     netdev@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH 1/7] rhashtable: silence RCU warning in rhashtable_test.

print_ht in rhashtable_test calls rht_dereference() with neither
RCU protection or the mutex.  This triggers an RCU warning.
So take the mutex to silence the warning.

Acked-by: Herbert Xu <herbert@...dor.apana.org.au>
Signed-off-by: NeilBrown <neilb@...e.com>
---
 lib/test_rhashtable.c |    3 +++
 1 file changed, 3 insertions(+)

diff --git a/lib/test_rhashtable.c b/lib/test_rhashtable.c
index fb6968109113..6ca59ffcacbe 100644
--- a/lib/test_rhashtable.c
+++ b/lib/test_rhashtable.c
@@ -501,6 +501,8 @@ static unsigned int __init print_ht(struct rhltable *rhlt)
 	unsigned int i, cnt = 0;
 
 	ht = &rhlt->ht;
+	/* Take the mutex to avoid RCU warning */
+	mutex_lock(&ht->mutex);
 	tbl = rht_dereference(ht->tbl, ht);
 	for (i = 0; i < tbl->size; i++) {
 		struct rhash_head *pos, *next;
@@ -534,6 +536,7 @@ static unsigned int __init print_ht(struct rhltable *rhlt)
 		}
 	}
 	printk(KERN_ERR "\n---- ht: ----%s\n-------------\n", buff);
+	mutex_unlock(&ht->mutex);
 
 	return cnt;
 }