* [PATCH net-next] ipv6: use rcu_dereference_bh() in ipv6_route_seq_next()
@ 2017-10-10 0:17 Wei Wang
2017-10-10 3:00 ` David Miller
0 siblings, 1 reply; 2+ messages in thread
From: Wei Wang @ 2017-10-10 0:17 UTC (permalink / raw)
To: David Miller, netdev; +Cc: Eric Dumazet, Martin KaFai Lau, Wei Wang
From: Wei Wang <weiwan@google.com>
This patch replaces rcu_deference() with rcu_dereference_bh() in
ipv6_route_seq_next() to avoid the following warning:
[ 19.431685] WARNING: suspicious RCU usage
[ 19.433451] 4.14.0-rc3-00914-g66f5d6c #118 Not tainted
[ 19.435509] -----------------------------
[ 19.437267] net/ipv6/ip6_fib.c:2259 suspicious
rcu_dereference_check() usage!
[ 19.440790]
[ 19.440790] other info that might help us debug this:
[ 19.440790]
[ 19.444734]
[ 19.444734] rcu_scheduler_active = 2, debug_locks = 1
[ 19.447757] 2 locks held by odhcpd/3720:
[ 19.449480] #0: (&p->lock){+.+.}, at: [<ffffffffb1231f7d>]
seq_read+0x3c/0x333
[ 19.452720] #1: (rcu_read_lock_bh){....}, at: [<ffffffffb1d2b984>]
ipv6_route_seq_start+0x5/0xfd
[ 19.456323]
[ 19.456323] stack backtrace:
[ 19.458812] CPU: 0 PID: 3720 Comm: odhcpd Not tainted
4.14.0-rc3-00914-g66f5d6c #118
[ 19.462042] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996),
BIOS 1.10.2-1 04/01/2014
[ 19.465414] Call Trace:
[ 19.466788] dump_stack+0x86/0xc0
[ 19.468358] lockdep_rcu_suspicious+0xea/0xf3
[ 19.470183] ipv6_route_seq_next+0x71/0x164
[ 19.471963] seq_read+0x244/0x333
[ 19.473522] proc_reg_read+0x48/0x67
[ 19.475152] ? proc_reg_write+0x67/0x67
[ 19.476862] __vfs_read+0x26/0x10b
[ 19.478463] ? __might_fault+0x37/0x84
[ 19.480148] vfs_read+0xba/0x146
[ 19.481690] SyS_read+0x51/0x8e
[ 19.483197] do_int80_syscall_32+0x66/0x15a
[ 19.484969] entry_INT80_compat+0x32/0x50
[ 19.486707] RIP: 0023:0xf7f0be8e
[ 19.488244] RSP: 002b:00000000ffa75d04 EFLAGS: 00000246 ORIG_RAX:
0000000000000003
[ 19.491431] RAX: ffffffffffffffda RBX: 0000000000000009 RCX:
0000000008056068
[ 19.493886] RDX: 0000000000001000 RSI: 0000000008056008 RDI:
0000000000001000
[ 19.496331] RBP: 00000000000001ff R08: 0000000000000000 R09:
0000000000000000
[ 19.498768] R10: 0000000000000000 R11: 0000000000000000 R12:
0000000000000000
[ 19.501217] R13: 0000000000000000 R14: 0000000000000000 R15:
0000000000000000
Fixes: 66f5d6ce53e6 ("ipv6: replace rwlock with rcu and spinlock in fib6_table")
Reported-by: Xiaolong Ye <xiaolong.ye@intel.com>
Signed-off-by: Wei Wang <weiwan@google.com>
Acked-by: Eric Dumazet <edumazet@google.com>
---
net/ipv6/ip6_fib.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/net/ipv6/ip6_fib.c b/net/ipv6/ip6_fib.c
index 52a29ba32928..c2ecd5ec638a 100644
--- a/net/ipv6/ip6_fib.c
+++ b/net/ipv6/ip6_fib.c
@@ -2262,7 +2262,7 @@ static void *ipv6_route_seq_next(struct seq_file *seq, void *v, loff_t *pos)
if (!v)
goto iter_table;
- n = rcu_dereference(((struct rt6_info *)v)->dst.rt6_next);
+ n = rcu_dereference_bh(((struct rt6_info *)v)->dst.rt6_next);
if (n) {
++*pos;
return n;
--
2.14.2.920.gcf0c67979c-goog
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH net-next] ipv6: use rcu_dereference_bh() in ipv6_route_seq_next()
2017-10-10 0:17 [PATCH net-next] ipv6: use rcu_dereference_bh() in ipv6_route_seq_next() Wei Wang
@ 2017-10-10 3:00 ` David Miller
0 siblings, 0 replies; 2+ messages in thread
From: David Miller @ 2017-10-10 3:00 UTC (permalink / raw)
To: weiwan; +Cc: netdev, edumazet, kafai
From: Wei Wang <weiwan@google.com>
Date: Mon, 9 Oct 2017 17:17:26 -0700
> From: Wei Wang <weiwan@google.com>
>
> This patch replaces rcu_deference() with rcu_dereference_bh() in
> ipv6_route_seq_next() to avoid the following warning:
...
> Fixes: 66f5d6ce53e6 ("ipv6: replace rwlock with rcu and spinlock in fib6_table")
> Reported-by: Xiaolong Ye <xiaolong.ye@intel.com>
> Signed-off-by: Wei Wang <weiwan@google.com>
> Acked-by: Eric Dumazet <edumazet@google.com>
Applied, thanks.
^ permalink raw reply [flat|nested] 2+ messages in thread
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