net/sctp: terminate rhashtable walk correctly

vegard · davem330 · commit 5fc382d87517 · 2016-07-25T17:43:57.000-07:00
I was seeing a lot of these: BUG: sleeping function called from invalid context at mm/slab.h:388 in_atomic(): 0, irqs_disabled(): 0, pid: 14971, name: trinity-c2 Preemption disabled at:[<ffffffff819bcd46>] rhashtable_walk_start+0x46/0x150 [<ffffffff81149abb>] preempt_count_add+0x1fb/0x280 [<ffffffff83295722>] _raw_spin_lock+0x12/0x40 [<ffffffff811aac87>] console_unlock+0x2f7/0x930 [<ffffffff811ab5bb>] vprintk_emit+0x2fb/0x520 [<ffffffff811aba6a>] vprintk_default+0x1a/0x20 [<ffffffff812c171a>] printk+0x94/0xb0 [<ffffffff811d6ed0>] print_stack_trace+0xe0/0x170 [<ffffffff8115835e>] ___might_sleep+0x3be/0x460 [<ffffffff81158490>] __might_sleep+0x90/0x1a0 [<ffffffff8139b823>] kmem_cache_alloc+0x153/0x1e0 [<ffffffff819bca1e>] rhashtable_walk_init+0xfe/0x2d0 [<ffffffff82ec64de>] sctp_transport_walk_start+0x1e/0x60 [<ffffffff82edd8ad>] sctp_transport_seq_start+0x4d/0x150 [<ffffffff8143a82b>] seq_read+0x27b/0x1180 [<ffffffff814f97fc>] proc_reg_read+0xbc/0x180 [<ffffffff813d471b>] __vfs_read+0xdb/0x610 [<ffffffff813d4d3a>] vfs_read+0xea/0x2d0 [<ffffffff813d615b>] SyS_pread64+0x11b/0x150 [<ffffffff8100334c>] do_syscall_64+0x19c/0x410 [<ffffffff832960a5>] return_from_SYSCALL_64+0x0/0x6a [<ffffffffffffffff>] 0xffffffffffffffff Apparently we always need to call rhashtable_walk_stop(), even when rhashtable_walk_start() fails: * rhashtable_walk_start - Start a hash table walk * @iter: Hash table iterator * * Start a hash table walk. Note that we take the RCU lock in all * cases including when we return an error. So you must always call * rhashtable_walk_stop to clean up. otherwise we never call rcu_read_unlock() and we get the splat above. Fixes: 53fa103 ("sctp: fix some rhashtable functions using in sctp proc/diag") See-also: 53fa103 ("sctp: fix some rhashtable functions using in sctp proc/diag") See-also: f2dba9c ("rhashtable: Introduce rhashtable_walk_*") Cc: Xin Long <lucien.xin@gmail.com> Cc: Herbert Xu <herbert@gondor.apana.org.au> Cc: stable@vger.kernel.org Signed-off-by: Vegard Nossum <vegard.nossum@oracle.com> Acked-by: Marcelo Ricardo Leitner <marcelo.leitner@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/sctp/socket.c b/net/sctp/socket.c
@@ -4393,6 +4393,7 @@ int sctp_transport_walk_start(struct rhashtable_iter *iter)
 
 	err = rhashtable_walk_start(iter);
 	if (err && err != -EAGAIN) {
+		rhashtable_walk_stop(iter);
 		rhashtable_walk_exit(iter);
 		return err;
 	}

Original file line number	Diff line number	Diff line change
`@@ -4393,6 +4393,7 @@ int sctp_transport_walk_start(struct rhashtable_iter *iter)`
`4393`	`4393`
`4394`	`4394`	`err = rhashtable_walk_start(iter);`
`4395`	`4395`	`if (err && err != -EAGAIN) {`
	`4396`	`+ rhashtable_walk_stop(iter);`
`4396`	`4397`	`rhashtable_walk_exit(iter);`
`4397`	`4398`	`return err;`
`4398`	`4399`	`}`