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

   1 From f9117482487441b19b19b14b0aad05bee8143e8d 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 019/366] 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 the existing dependency chain (in reverse order) is:
  19
  20 -> #1 (sk_lock-AF_INET){+.+...}:
  21        [<ffffffff810836e5>] lock_acquire+0x103/0x12e
  22        [<ffffffff813e2781>] lock_sock_nested+0x82/0x92
  23        [<ffffffff81433308>] lock_sock+0x10/0x12
  24        [<ffffffff81433afa>] tcp_close+0x1b/0x355
  25        [<ffffffff81453c99>] inet_release+0xc3/0xcd
  26        [<ffffffff813dff3f>] sock_release+0x1f/0x74
  27        [<ffffffff813dffbb>] sock_close+0x27/0x2b
  28        [<ffffffff81129c63>] fput+0x11d/0x1e3
  29        [<ffffffff81126577>] filp_close+0x70/0x7b
  30        [<ffffffff8112667a>] sys_close+0xf8/0x13d
  31        [<ffffffff814ae882>] system_call_fastpath+0x16/0x1b
  32
  33 -> #0 (local_softirq_lock){+.+...}:
  34        [<ffffffff81082ecc>] __lock_acquire+0xacc/0xdc8
  35        [<ffffffff810836e5>] lock_acquire+0x103/0x12e
  36        [<ffffffff814a7e40>] _raw_spin_lock+0x3b/0x4a
  37        [<ffffffff81056d12>] __local_lock+0x25/0x68
  38        [<ffffffff81056d8b>] local_bh_disable+0x36/0x3b
  39        [<ffffffff814a7fc4>] _raw_write_lock_bh+0x16/0x4f
  40        [<ffffffff81433c38>] tcp_close+0x159/0x355
  41        [<ffffffff81453c99>] inet_release+0xc3/0xcd
  42        [<ffffffff813dff3f>] sock_release+0x1f/0x74
  43        [<ffffffff813dffbb>] sock_close+0x27/0x2b
  44        [<ffffffff81129c63>] fput+0x11d/0x1e3
  45        [<ffffffff81126577>] filp_close+0x70/0x7b
  46        [<ffffffff8112667a>] sys_close+0xf8/0x13d
  47        [<ffffffff814ae882>] system_call_fastpath+0x16/0x1b
  48
  49 other info that might help us debug this:
  50
  51  Possible unsafe locking scenario:
  52
  53        CPU0                    CPU1
  54        ----                    ----
  55   lock(sk_lock-AF_INET);
  56                                lock(local_softirq_lock);
  57                                lock(sk_lock-AF_INET);
  58   lock(local_softirq_lock);
  59
  60  *** DEADLOCK ***
  61
  62 1 lock held by ip/1104:
  63  #0:  (sk_lock-AF_INET){+.+...}, at: [<ffffffff81433308>] lock_sock+0x10/0x12
  64
  65 stack backtrace:
  66 Pid: 1104, comm: ip Not tainted 3.0.0-rc3+ #26
  67 Call Trace:
  68  [<ffffffff81081649>] print_circular_bug+0x1f8/0x209
  69  [<ffffffff81082ecc>] __lock_acquire+0xacc/0xdc8
  70  [<ffffffff81056d12>] ? __local_lock+0x25/0x68
  71  [<ffffffff810836e5>] lock_acquire+0x103/0x12e
  72  [<ffffffff81056d12>] ? __local_lock+0x25/0x68
  73  [<ffffffff81046c75>] ? get_parent_ip+0x11/0x41
  74  [<ffffffff814a7e40>] _raw_spin_lock+0x3b/0x4a
  75  [<ffffffff81056d12>] ? __local_lock+0x25/0x68
  76  [<ffffffff81046c8c>] ? get_parent_ip+0x28/0x41
  77  [<ffffffff81056d12>] __local_lock+0x25/0x68
  78  [<ffffffff81056d8b>] local_bh_disable+0x36/0x3b
  79  [<ffffffff81433308>] ? lock_sock+0x10/0x12
  80  [<ffffffff814a7fc4>] _raw_write_lock_bh+0x16/0x4f
  81  [<ffffffff81433c38>] tcp_close+0x159/0x355
  82  [<ffffffff81453c99>] inet_release+0xc3/0xcd
  83  [<ffffffff813dff3f>] sock_release+0x1f/0x74
  84  [<ffffffff813dffbb>] sock_close+0x27/0x2b
  85  [<ffffffff81129c63>] fput+0x11d/0x1e3
  86  [<ffffffff81126577>] filp_close+0x70/0x7b
  87  [<ffffffff8112667a>] sys_close+0xf8/0x13d
  88  [<ffffffff814ae882>] system_call_fastpath+0x16/0x1b
  89
  90 Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
  91 ---
  92  net/core/sock.c | 3 +--
  93  1 file changed, 1 insertion(+), 2 deletions(-)
  94
  95 diff --git a/net/core/sock.c b/net/core/sock.c
  96 index f367df3..d578b70 100644
  97 --- a/net/core/sock.c
  98 +++ b/net/core/sock.c
  99 @@ -2439,12 +2439,11 @@ void lock_sock_nested(struct sock *sk, int subclass)
 100         if (sk->sk_lock.owned)
 101                 __lock_sock(sk);
 102         sk->sk_lock.owned = 1;
 103 -       spin_unlock(&sk->sk_lock.slock);
 104 +       spin_unlock_bh(&sk->sk_lock.slock);
 105         /*
 106          * The sk_lock has mutex_lock() semantics here:
 107          */
 108         mutex_acquire(&sk->sk_lock.dep_map, subclass, 0, _RET_IP_);
 109 -       local_bh_enable();
 110  }
 111  EXPORT_SYMBOL(lock_sock_nested);
 112
 113 --
 114 1.9.1
 115