batman-adv/patches/0002-batman-adv-Avoid-duplicate-neigh_node-additions.patch

   1 From 8013ae257447c99d7ba037967458f91ceb4051ae Mon Sep 17 00:00:00 2001
   2 From: =?UTF-8?q?Linus=20L=C3=BCssing?= <linus.luessing@c0d3.blue>
   3 Date: Thu, 7 Jan 2016 08:11:12 +0100
   4 Subject: [PATCH 2/6] batman-adv: Avoid duplicate neigh_node additions
   5 MIME-Version: 1.0
   6 Content-Type: text/plain; charset=UTF-8
   7 Content-Transfer-Encoding: 8bit
   8
   9 Two parallel calls to batadv_neigh_node_new() might race for creating
  10 and adding the same neig_node. Fix this by including the check for any
  11 already existing, identical neigh_node within the spin-lock.
  12
  13 This fixes splats like the following:
  14
  15 [  739.535069] ------------[ cut here ]------------
  16 [  739.535079] WARNING: CPU: 0 PID: 0 at /usr/src/batman-adv/git/batman-adv/net/batman-adv/bat_iv_ogm.c:1004 batadv_iv_ogm_process_per_outif+0xe3f/0xe60 [batman_adv]()
  17 [  739.535092] too many matching neigh_nodes
  18 [  739.535094] Modules linked in: dm_mod tun ip6table_filter ip6table_mangle ip6table_nat nf_nat_ipv6 ip6_tables xt_nat iptable_nat nf_nat_ipv4 nf_nat xt_TCPMSS xt_mark iptable_mangle xt_tcpudp xt_conntrack iptable_filter ip_tables x_tables ip_gre ip_tunnel gre bridge stp llc thermal_sys kvm_intel kvm crct10dif_pclmul crc32_pclmul sha256_ssse3 sha256_generic hmac drbg ansi_cprng aesni_intel aes_x86_64 lrw gf128mul glue_helper ablk_helper cryptd evdev pcspkr ip6_gre ip6_tunnel tunnel6 batman_adv(O) libcrc32c nf_conntrack_ipv6 nf_defrag_ipv6 nf_conntrack_ipv4 nf_defrag_ipv4 nf_conntrack autofs4 ext4 crc16 mbcache jbd2 xen_netfront xen_blkfront crc32c_intel
  19 [  739.535177] CPU: 0 PID: 0 Comm: swapper/0 Tainted: G        W  O    4.2.0-0.bpo.1-amd64 #1 Debian 4.2.6-3~bpo8+2
  20 [  739.535186]  0000000000000000 ffffffffa013b050 ffffffff81554521 ffff88007d003c18
  21 [  739.535201]  ffffffff8106fa01 0000000000000000 ffff8800047a087a ffff880079c3a000
  22 [  739.735602]  ffff88007b82bf40 ffff88007bc2d1c0 ffffffff8106fa7a ffffffffa013aa8e
  23 [  739.735624] Call Trace:
  24 [  739.735639]  <IRQ>  [<ffffffff81554521>] ? dump_stack+0x40/0x50
  25 [  739.735677]  [<ffffffff8106fa01>] ? warn_slowpath_common+0x81/0xb0
  26 [  739.735692]  [<ffffffff8106fa7a>] ? warn_slowpath_fmt+0x4a/0x50
  27 [  739.735715]  [<ffffffffa012448f>] ? batadv_iv_ogm_process_per_outif+0xe3f/0xe60 [batman_adv]
  28 [  739.735740]  [<ffffffffa0124813>] ? batadv_iv_ogm_receive+0x363/0x380 [batman_adv]
  29 [  739.735762]  [<ffffffffa0124813>] ? batadv_iv_ogm_receive+0x363/0x380 [batman_adv]
  30 [  739.735783]  [<ffffffff810b0841>] ? __raw_callee_save___pv_queued_spin_unlock+0x11/0x20
  31 [  739.735804]  [<ffffffffa012cb39>] ? batadv_batman_skb_recv+0xc9/0x110 [batman_adv]
  32 [  739.735825]  [<ffffffff81464891>] ? __netif_receive_skb_core+0x841/0x9a0
  33 [  739.735838]  [<ffffffff810b0841>] ? __raw_callee_save___pv_queued_spin_unlock+0x11/0x20
  34 [  739.735853]  [<ffffffff81465681>] ? process_backlog+0xa1/0x140
  35 [  739.735864]  [<ffffffff81464f1a>] ? net_rx_action+0x20a/0x320
  36 [  739.735878]  [<ffffffff81073aa7>] ? __do_softirq+0x107/0x270
  37 [  739.735891]  [<ffffffff81073d82>] ? irq_exit+0x92/0xa0
  38 [  739.735905]  [<ffffffff8137e0d1>] ? xen_evtchn_do_upcall+0x31/0x40
  39 [  739.735924]  [<ffffffff8155b8fe>] ? xen_do_hypervisor_callback+0x1e/0x40
  40 [  739.735939]  <EOI>  [<ffffffff810013aa>] ? xen_hypercall_sched_op+0xa/0x20
  41 [  739.735965]  [<ffffffff810013aa>] ? xen_hypercall_sched_op+0xa/0x20
  42 [  739.735979]  [<ffffffff8100a39c>] ? xen_safe_halt+0xc/0x20
  43 [  739.735991]  [<ffffffff8101da6c>] ? default_idle+0x1c/0xa0
  44 [  739.736004]  [<ffffffff810abf6b>] ? cpu_startup_entry+0x2eb/0x350
  45 [  739.736019]  [<ffffffff81b2af5e>] ? start_kernel+0x480/0x48b
  46 [  739.736032]  [<ffffffff81b2d116>] ? xen_start_kernel+0x507/0x511
  47 [  739.736048] ---[ end trace c106bb901244bc8c ]---
  48
  49 Reported-by: Martin Weinelt <martin@darmstadt.freifunk.net>
  50 Signed-off-by: Linus Lüssing <linus.luessing@c0d3.blue>
  51 Signed-off-by: Marek Lindner <mareklindner@neomailbox.ch>
  52 ---
  53  net/batman-adv/originator.c | 6 ++++--
  54  1 file changed, 4 insertions(+), 2 deletions(-)
  55
  56 diff --git a/net/batman-adv/originator.c b/net/batman-adv/originator.c
  57 index c355a82..28241a4 100644
  58 --- a/net/batman-adv/originator.c
  59 +++ b/net/batman-adv/originator.c
  60 @@ -630,6 +630,8 @@ batadv_neigh_node_new(struct batadv_orig_node *orig_node,
  61         struct batadv_neigh_node *neigh_node;
  62         struct batadv_hardif_neigh_node *hardif_neigh = NULL;
  63
  64 +       spin_lock_bh(&orig_node->neigh_list_lock);
  65 +
  66         neigh_node = batadv_neigh_node_get(orig_node, hard_iface, neigh_addr);
  67         if (neigh_node)
  68                 goto out;
  69 @@ -666,15 +668,15 @@ batadv_neigh_node_new(struct batadv_orig_node *orig_node,
  70         kref_init(&neigh_node->refcount);
  71         kref_get(&neigh_node->refcount);
  72
  73 -       spin_lock_bh(&orig_node->neigh_list_lock);
  74         hlist_add_head_rcu(&neigh_node->list, &orig_node->neigh_list);
  75 -       spin_unlock_bh(&orig_node->neigh_list_lock);
  76
  77         batadv_dbg(BATADV_DBG_BATMAN, orig_node->bat_priv,
  78                    "Creating new neighbor %pM for orig_node %pM on interface %s\n",
  79                    neigh_addr, orig_node->orig, hard_iface->net_dev->name);
  80
  81  out:
  82 +       spin_unlock_bh(&orig_node->neigh_list_lock);
  83 +
  84         if (hardif_neigh)
  85                 batadv_hardif_neigh_put(hardif_neigh);
  86         return neigh_node;
  87 --
  88 2.8.0.rc3
  89