diff options
| author | Qian Cai <cai@lca.pw> | 2020-03-25 18:01:00 -0400 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2020-03-29 21:51:28 -0700 |
| commit | fbe4e0c1b298b4665ee6915266c9d6c5b934ef4a (patch) | |
| tree | 252ed77607e3046cb3ff8b99e5306f409cb716bb /net/ipv4 | |
| parent | be8c827f50a0bcd56361b31ada11dc0a3c2fd240 (diff) | |
ipv4: fix a RCU-list lock in fib_triestat_seq_show
fib_triestat_seq_show() calls hlist_for_each_entry_rcu(tb, head,
tb_hlist) without rcu_read_lock() will trigger a warning,
net/ipv4/fib_trie.c:2579 RCU-list traversed in non-reader section!!
other info that might help us debug this:
rcu_scheduler_active = 2, debug_locks = 1
1 lock held by proc01/115277:
#0: c0000014507acf00 (&p->lock){+.+.}-{3:3}, at: seq_read+0x58/0x670
Call Trace:
dump_stack+0xf4/0x164 (unreliable)
lockdep_rcu_suspicious+0x140/0x164
fib_triestat_seq_show+0x750/0x880
seq_read+0x1a0/0x670
proc_reg_read+0x10c/0x1b0
__vfs_read+0x3c/0x70
vfs_read+0xac/0x170
ksys_read+0x7c/0x140
system_call+0x5c/0x68
Fix it by adding a pair of rcu_read_lock/unlock() and use
cond_resched_rcu() to avoid the situation where walking of a large
number of items may prevent scheduling for a long time.
Signed-off-by: Qian Cai <cai@lca.pw>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/ipv4')
| -rw-r--r-- | net/ipv4/fib_trie.c | 3 |
1 files changed, 3 insertions, 0 deletions
diff --git a/net/ipv4/fib_trie.c b/net/ipv4/fib_trie.c index ff0c24371e33..3be0affbabd3 100644 --- a/net/ipv4/fib_trie.c +++ b/net/ipv4/fib_trie.c @@ -2577,6 +2577,7 @@ static int fib_triestat_seq_show(struct seq_file *seq, void *v) " %zd bytes, size of tnode: %zd bytes.\n", LEAF_SIZE, TNODE_SIZE(0)); + rcu_read_lock(); for (h = 0; h < FIB_TABLE_HASHSZ; h++) { struct hlist_head *head = &net->ipv4.fib_table_hash[h]; struct fib_table *tb; @@ -2596,7 +2597,9 @@ static int fib_triestat_seq_show(struct seq_file *seq, void *v) trie_show_usage(seq, t->stats); #endif } + cond_resched_rcu(); } + rcu_read_unlock(); return 0; } |