netdev - [PATCH] rhashtable: add restart routine in rhashtable_free_and

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Message-Id: <20180703131909.30401-1-ap420073@gmail.com>
Date:   Tue,  3 Jul 2018 22:19:09 +0900
From:   Taehee Yoo <ap420073@...il.com>
To:     davem@...emloft.net, tgraf@...g.ch, herbert@...dor.apana.org.au
Cc:     netdev@...r.kernel.org, fw@...len.de, pablo@...filter.org,
        ap420073@...il.com
Subject: [PATCH] rhashtable: add restart routine in rhashtable_free_and_destroy()

rhashtable_free_and_destroy() cancels re-hash deferred work
then walks and destroys elements. at this moment, some elements can be
still in future_tbl. that elements are not destroyed.

test case:
 nft_rhash_destroy() calls rhashtable_free_and_destroy() to destroy
 all elements of sets before destroying sets and chains.
 But rhashtable_free_and_destroy() doesn't destroy elements of future_tbl.
 so that splat occurred.

test script:
   %cat test.nft
   table ip aa {
	   map map1 {
		   type ipv4_addr : verdict;
		   elements = {
			   0 : jump a0,
			   1 : jump a0,
			   2 : jump a0,
			   3 : jump a0,
			   4 : jump a0,
			   5 : jump a0,
			   6 : jump a0,
			   7 : jump a0,
			   8 : jump a0,
			   9 : jump a0,
		   }
	   }
	   chain a0 {
	   }
   }
   flush ruleset
   table ip aa {
	   map map1 {
		   type ipv4_addr : verdict;
		   elements = {
		   0 : jump a0,
		   1 : jump a0,
		   2 : jump a0,
		   3 : jump a0,
		   4 : jump a0,
		   5 : jump a0,
		   6 : jump a0,
		   7 : jump a0,
		   8 : jump a0,
		   9 : jump a0,
		   }
	   }
	   chain a0 {
	   }
   }
   flush ruleset

   %while :; do nft -f test.nft; done

Splat looks like:
[  200.795603] kernel BUG at net/netfilter/nf_tables_api.c:1363!
[  200.806944] invalid opcode: 0000 [#1] SMP DEBUG_PAGEALLOC KASAN PTI
[  200.812253] CPU: 1 PID: 1582 Comm: nft Not tainted 4.17.0+ #24
[  200.820297] Hardware name: To be filled by O.E.M. To be filled by O.E.M./Aptio CRB, BIOS 5.6.5 07/08/2015
[  200.830309] RIP: 0010:nf_tables_chain_destroy.isra.34+0x62/0x240 [nf_tables]
[  200.838317] Code: 43 50 85 c0 74 26 48 8b 45 00 48 8b 4d 08 ba 54 05 00 00 48 c7 c6 60 6d 29 c0 48 c7 c7 c0 65 29 c0 4c 8b 40 08 e8 58 e5 fd f8 <0f> 0b 48 89 da 48 b8 00 00 00 00 00 fc ff
[  200.860366] RSP: 0000:ffff880118dbf4d0 EFLAGS: 00010282
[  200.866354] RAX: 0000000000000061 RBX: ffff88010cdeaf08 RCX: 0000000000000000
[  200.874355] RDX: 0000000000000061 RSI: 0000000000000008 RDI: ffffed00231b7e90
[  200.882361] RBP: ffff880118dbf4e8 R08: ffffed002373bcfb R09: ffffed002373bcfa
[  200.890354] R10: 0000000000000000 R11: ffffed002373bcfb R12: dead000000000200
[  200.898356] R13: dead000000000100 R14: ffffffffbb62af38 R15: dffffc0000000000
[  200.906354] FS:  00007fefc31fd700(0000) GS:ffff88011b800000(0000) knlGS:0000000000000000
[  200.915533] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[  200.922355] CR2: 0000557f1c8e9128 CR3: 0000000106880000 CR4: 00000000001006e0
[  200.930353] Call Trace:
[  200.932351]  ? nf_tables_commit+0x26f6/0x2c60 [nf_tables]
[  200.939525]  ? nf_tables_setelem_notify.constprop.49+0x1a0/0x1a0 [nf_tables]
[  200.947525]  ? nf_tables_delchain+0x6e0/0x6e0 [nf_tables]
[  200.952383]  ? nft_add_set_elem+0x1700/0x1700 [nf_tables]
[  200.959532]  ? nla_parse+0xab/0x230
[  200.963529]  ? nfnetlink_rcv_batch+0xd06/0x10d0 [nfnetlink]
[  200.968384]  ? nfnetlink_net_init+0x130/0x130 [nfnetlink]
[  200.975525]  ? debug_show_all_locks+0x290/0x290
[  200.980363]  ? debug_show_all_locks+0x290/0x290
[  200.986356]  ? sched_clock_cpu+0x132/0x170
[  200.990352]  ? find_held_lock+0x39/0x1b0
[  200.994355]  ? sched_clock_local+0x10d/0x130
[  200.999531]  ? memset+0x1f/0x40


Signed-off-by: Taehee Yoo <ap420073@...il.com>
---
 lib/rhashtable.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/lib/rhashtable.c b/lib/rhashtable.c
index 0e04947..8ea27fa 100644
--- a/lib/rhashtable.c
+++ b/lib/rhashtable.c
@@ -1134,6 +1134,7 @@ void rhashtable_free_and_destroy(struct rhashtable *ht,
 	mutex_lock(&ht->mutex);
 	tbl = rht_dereference(ht->tbl, ht);
 	if (free_fn) {
+restart:
 		for (i = 0; i < tbl->size; i++) {
 			struct rhash_head *pos, *next;
 
@@ -1147,9 +1148,11 @@ void rhashtable_free_and_destroy(struct rhashtable *ht,
 					rht_dereference(pos->next, ht) : NULL)
 				rhashtable_free_one(ht, pos, free_fn, arg);
 		}
+		tbl = rht_dereference(tbl->future_tbl, ht);
+		if (tbl)
+			goto restart;
 	}
-
-	bucket_table_free(tbl);
+	bucket_table_free(rht_dereference(ht->tbl, ht));
 	mutex_unlock(&ht->mutex);
 }
 EXPORT_SYMBOL_GPL(rhashtable_free_and_destroy);
-- 
2.9.3