From: Haggai Eran Date: Tue, 7 Jul 2015 14:45:13 +0000 (+0300) Subject: IB/ipoib: Prevent lockdep warning in __ipoib_ib_dev_flush X-Git-Tag: firefly_0821_release~176^2~1261^2~15 X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=8b7cce0dae956b329d09099f8739821936cf7c0f;p=firefly-linux-kernel-4.4.55.git IB/ipoib: Prevent lockdep warning in __ipoib_ib_dev_flush __ipoib_ib_dev_flush calls itself recursively on child devices, and lockdep complains about locking vlan_rwsem twice (see below). Use down_read_nested instead of down_read to prevent the warning. ============================================= [ INFO: possible recursive locking detected ] 4.1.0-rc4+ #36 Tainted: G O --------------------------------------------- kworker/u20:2/261 is trying to acquire lock: (&priv->vlan_rwsem){.+.+..}, at: [] __ipoib_ib_dev_flush+0x3a/0x2b0 [ib_ipoib] but task is already holding lock: (&priv->vlan_rwsem){.+.+..}, at: [] __ipoib_ib_dev_flush+0x3a/0x2b0 [ib_ipoib] other info that might help us debug this: Possible unsafe locking scenario: CPU0 ---- lock(&priv->vlan_rwsem); lock(&priv->vlan_rwsem); *** DEADLOCK *** May be due to missing lock nesting notation 3 locks held by kworker/u20:2/261: #0: ("%s""ipoib_flush"){.+.+..}, at: [] process_one_work+0x15c/0x760 #1: ((&priv->flush_heavy)){+.+...}, at: [] process_one_work+0x15c/0x760 #2: (&priv->vlan_rwsem){.+.+..}, at: [] __ipoib_ib_dev_flush+0x3a/0x2b0 [ib_ipoib] stack backtrace: CPU: 3 PID: 261 Comm: kworker/u20:2 Tainted: G O 4.1.0-rc4+ #36 Hardware name: Red Hat KVM, BIOS 0.5.1 01/01/2007 Workqueue: ipoib_flush ipoib_ib_dev_flush_heavy [ib_ipoib] ffff8801c6c54790 ffff8801c9927af8 ffffffff81665238 0000000000000001 ffffffff825b5b30 ffff8801c9927bd8 ffffffff810bba51 ffff880100000000 ffffffff00000001 ffff880100000001 ffff8801c6c55428 ffff8801c6c54790 Call Trace: [] dump_stack+0x4f/0x6f [] __lock_acquire+0x741/0x1820 [] lock_acquire+0xc8/0x240 [] ? __ipoib_ib_dev_flush+0x3a/0x2b0 [ib_ipoib] [] down_read+0x4c/0x70 [] ? __ipoib_ib_dev_flush+0x3a/0x2b0 [ib_ipoib] [] __ipoib_ib_dev_flush+0x3a/0x2b0 [ib_ipoib] [] __ipoib_ib_dev_flush+0x5a/0x2b0 [ib_ipoib] [] ipoib_ib_dev_flush_heavy+0x1a/0x20 [ib_ipoib] [] process_one_work+0x201/0x760 [] ? process_one_work+0x15c/0x760 [] worker_thread+0x120/0x4d0 [] ? process_one_work+0x760/0x760 [] ? process_one_work+0x760/0x760 [] kthread+0xfe/0x120 [] ? __init_kthread_worker+0x70/0x70 [] ret_from_fork+0x42/0x70 [] ? __init_kthread_worker+0x70/0x70 Signed-off-by: Haggai Eran Signed-off-by: Doug Ledford --- diff --git a/drivers/infiniband/ulp/ipoib/ipoib_ib.c b/drivers/infiniband/ulp/ipoib/ipoib_ib.c index 63b92cbb29ad..058150ff5aa1 100644 --- a/drivers/infiniband/ulp/ipoib/ipoib_ib.c +++ b/drivers/infiniband/ulp/ipoib/ipoib_ib.c @@ -985,20 +985,21 @@ static inline int update_child_pkey(struct ipoib_dev_priv *priv) } static void __ipoib_ib_dev_flush(struct ipoib_dev_priv *priv, - enum ipoib_flush_level level) + enum ipoib_flush_level level, + int nesting) { struct ipoib_dev_priv *cpriv; struct net_device *dev = priv->dev; int result; - down_read(&priv->vlan_rwsem); + down_read_nested(&priv->vlan_rwsem, nesting); /* * Flush any child interfaces too -- they might be up even if * the parent is down. */ list_for_each_entry(cpriv, &priv->child_intfs, list) - __ipoib_ib_dev_flush(cpriv, level); + __ipoib_ib_dev_flush(cpriv, level, nesting + 1); up_read(&priv->vlan_rwsem); @@ -1076,7 +1077,7 @@ void ipoib_ib_dev_flush_light(struct work_struct *work) struct ipoib_dev_priv *priv = container_of(work, struct ipoib_dev_priv, flush_light); - __ipoib_ib_dev_flush(priv, IPOIB_FLUSH_LIGHT); + __ipoib_ib_dev_flush(priv, IPOIB_FLUSH_LIGHT, 0); } void ipoib_ib_dev_flush_normal(struct work_struct *work) @@ -1084,7 +1085,7 @@ void ipoib_ib_dev_flush_normal(struct work_struct *work) struct ipoib_dev_priv *priv = container_of(work, struct ipoib_dev_priv, flush_normal); - __ipoib_ib_dev_flush(priv, IPOIB_FLUSH_NORMAL); + __ipoib_ib_dev_flush(priv, IPOIB_FLUSH_NORMAL, 0); } void ipoib_ib_dev_flush_heavy(struct work_struct *work) @@ -1092,7 +1093,7 @@ void ipoib_ib_dev_flush_heavy(struct work_struct *work) struct ipoib_dev_priv *priv = container_of(work, struct ipoib_dev_priv, flush_heavy); - __ipoib_ib_dev_flush(priv, IPOIB_FLUSH_HEAVY); + __ipoib_ib_dev_flush(priv, IPOIB_FLUSH_HEAVY, 0); } void ipoib_ib_dev_cleanup(struct net_device *dev)