rt-patches/0019-net-flip-lock-dep-thingy.patch.patch

   1 From 7580f9f7b871328ae3eeef8b111166bb28233081 Mon Sep 17 00:00:00 2001
   2 From: Thomas Gleixner <tglx@linutronix.de>
   3 Date: Tue, 28 Jun 2011 10:59:58 +0200
   4 Subject: [PATCH 019/365] net-flip-lock-dep-thingy.patch
   5
   6 =======================================================
   7 [ INFO: possible circular locking dependency detected ]
   8 3.0.0-rc3+ #26
   9 -------------------------------------------------------
  10 ip/1104 is trying to acquire lock:
  11  (local_softirq_lock){+.+...}, at: [<ffffffff81056d12>] __local_lock+0x25/0x68
  12
  13 but task is already holding lock:
  14  (sk_lock-AF_INET){+.+...}, at: [<ffffffff81433308>] lock_sock+0x10/0x12
  15
  16 which lock already depends on the new lock.
  17
  18
  19 the existing dependency chain (in reverse order) is:
  20
  21 -> #1 (sk_lock-AF_INET){+.+...}:
  22        [<ffffffff810836e5>] lock_acquire+0x103/0x12e
  23        [<ffffffff813e2781>] lock_sock_nested+0x82/0x92
  24        [<ffffffff81433308>] lock_sock+0x10/0x12
  25        [<ffffffff81433afa>] tcp_close+0x1b/0x355
  26        [<ffffffff81453c99>] inet_release+0xc3/0xcd
  27        [<ffffffff813dff3f>] sock_release+0x1f/0x74
  28        [<ffffffff813dffbb>] sock_close+0x27/0x2b
  29        [<ffffffff81129c63>] fput+0x11d/0x1e3
  30        [<ffffffff81126577>] filp_close+0x70/0x7b
  31        [<ffffffff8112667a>] sys_close+0xf8/0x13d
  32        [<ffffffff814ae882>] system_call_fastpath+0x16/0x1b
  33
  34 -> #0 (local_softirq_lock){+.+...}:
  35        [<ffffffff81082ecc>] __lock_acquire+0xacc/0xdc8
  36        [<ffffffff810836e5>] lock_acquire+0x103/0x12e
  37        [<ffffffff814a7e40>] _raw_spin_lock+0x3b/0x4a
  38        [<ffffffff81056d12>] __local_lock+0x25/0x68
  39        [<ffffffff81056d8b>] local_bh_disable+0x36/0x3b
  40        [<ffffffff814a7fc4>] _raw_write_lock_bh+0x16/0x4f
  41        [<ffffffff81433c38>] tcp_close+0x159/0x355
  42        [<ffffffff81453c99>] inet_release+0xc3/0xcd
  43        [<ffffffff813dff3f>] sock_release+0x1f/0x74
  44        [<ffffffff813dffbb>] sock_close+0x27/0x2b
  45        [<ffffffff81129c63>] fput+0x11d/0x1e3
  46        [<ffffffff81126577>] filp_close+0x70/0x7b
  47        [<ffffffff8112667a>] sys_close+0xf8/0x13d
  48        [<ffffffff814ae882>] system_call_fastpath+0x16/0x1b
  49
  50 other info that might help us debug this:
  51
  52  Possible unsafe locking scenario:
  53
  54        CPU0                    CPU1
  55        ----                    ----
  56   lock(sk_lock-AF_INET);
  57                                lock(local_softirq_lock);
  58                                lock(sk_lock-AF_INET);
  59   lock(local_softirq_lock);
  60
  61  *** DEADLOCK ***
  62
  63 1 lock held by ip/1104:
  64  #0:  (sk_lock-AF_INET){+.+...}, at: [<ffffffff81433308>] lock_sock+0x10/0x12
  65
  66 stack backtrace:
  67 Pid: 1104, comm: ip Not tainted 3.0.0-rc3+ #26
  68 Call Trace:
  69  [<ffffffff81081649>] print_circular_bug+0x1f8/0x209
  70  [<ffffffff81082ecc>] __lock_acquire+0xacc/0xdc8
  71  [<ffffffff81056d12>] ? __local_lock+0x25/0x68
  72  [<ffffffff810836e5>] lock_acquire+0x103/0x12e
  73  [<ffffffff81056d12>] ? __local_lock+0x25/0x68
  74  [<ffffffff81046c75>] ? get_parent_ip+0x11/0x41
  75  [<ffffffff814a7e40>] _raw_spin_lock+0x3b/0x4a
  76  [<ffffffff81056d12>] ? __local_lock+0x25/0x68
  77  [<ffffffff81046c8c>] ? get_parent_ip+0x28/0x41
  78  [<ffffffff81056d12>] __local_lock+0x25/0x68
  79  [<ffffffff81056d8b>] local_bh_disable+0x36/0x3b
  80  [<ffffffff81433308>] ? lock_sock+0x10/0x12
  81  [<ffffffff814a7fc4>] _raw_write_lock_bh+0x16/0x4f
  82  [<ffffffff81433c38>] tcp_close+0x159/0x355
  83  [<ffffffff81453c99>] inet_release+0xc3/0xcd
  84  [<ffffffff813dff3f>] sock_release+0x1f/0x74
  85  [<ffffffff813dffbb>] sock_close+0x27/0x2b
  86  [<ffffffff81129c63>] fput+0x11d/0x1e3
  87  [<ffffffff81126577>] filp_close+0x70/0x7b
  88  [<ffffffff8112667a>] sys_close+0xf8/0x13d
  89  [<ffffffff814ae882>] system_call_fastpath+0x16/0x1b
  90
  91
  92 Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
  93 ---
  94  net/core/sock.c | 3 +--
  95  1 file changed, 1 insertion(+), 2 deletions(-)
  96
  97 diff --git a/net/core/sock.c b/net/core/sock.c
  98 index f4c0917..03ba648 100644
  99 --- a/net/core/sock.c
 100 +++ b/net/core/sock.c
 101 @@ -2436,12 +2436,11 @@ void lock_sock_nested(struct sock *sk, int subclass)
 102         if (sk->sk_lock.owned)
 103                 __lock_sock(sk);
 104         sk->sk_lock.owned = 1;
 105 -       spin_unlock(&sk->sk_lock.slock);
 106 +       spin_unlock_bh(&sk->sk_lock.slock);
 107         /*
 108          * The sk_lock has mutex_lock() semantics here:
 109          */
 110         mutex_acquire(&sk->sk_lock.dep_map, subclass, 0, _RET_IP_);
 111 -       local_bh_enable();
 112  }
 113  EXPORT_SYMBOL(lock_sock_nested);
 114
 115 --
 116 2.7.4
 117