From 9c6f42e9254150d2772242d9f8bd8d0b7b7431ff Mon Sep 17 00:00:00 2001 From: Shalom Lagziel Date: Sun, 24 Sep 2017 21:46:32 +0300 Subject: [PATCH] IB/ipoib: Fix sysfs Pkey create<->remove possible deadlock A possible ABBA lock can happen with RTNL and vlan_rwsem. For example: Flow A: Device Flush __ipoib_ib_dev_flush down_read(vlan_rwsem) // Lock A ipoib_flush_ah flush_workqueue(priv->wq) // Wait for completion A work on shared WQ (Mcast carrier) ipoib_mcast_carrier_on_task while (!rtnl_trylock()) // Wait for lock B Flow B: Sysfs PKEY delete ipoib_vlan_delete lock(RTNL) // Lock B down_write(vlan_rwsem) // Wait for lock A This can happen with PKEY creates as well. The solution is to release the RTNL lock in sysfs functions in case it is not possible to lock VLAN RW semaphore and reset the SYS call. Fixes: 69956d83267e ("IB/ipoib: Sync between remove_one to sysfs calls that use rtnl_lock") Signed-off-by: Shalom Lagziel Signed-off-by: Alex Vesker Signed-off-by: Leon Romanovsky Signed-off-by: Doug Ledford --- drivers/infiniband/ulp/ipoib/ipoib_vlan.c | 20 ++++++++++++++------ 1 file changed, 14 insertions(+), 6 deletions(-) diff --git a/drivers/infiniband/ulp/ipoib/ipoib_vlan.c b/drivers/infiniband/ulp/ipoib/ipoib_vlan.c index 9927cd6b7082..e01c58edca15 100644 --- a/drivers/infiniband/ulp/ipoib/ipoib_vlan.c +++ b/drivers/infiniband/ulp/ipoib/ipoib_vlan.c @@ -141,14 +141,17 @@ int ipoib_vlan_add(struct net_device *pdev, unsigned short pkey) return restart_syscall(); } - priv = ipoib_intf_alloc(ppriv->ca, ppriv->port, intf_name); - if (!priv) { + if (!down_write_trylock(&ppriv->vlan_rwsem)) { rtnl_unlock(); mutex_unlock(&ppriv->sysfs_mutex); - return -ENOMEM; + return restart_syscall(); } - down_write(&ppriv->vlan_rwsem); + priv = ipoib_intf_alloc(ppriv->ca, ppriv->port, intf_name); + if (!priv) { + result = -ENOMEM; + goto out; + } /* * First ensure this isn't a duplicate. We check the parent device and @@ -175,7 +178,7 @@ int ipoib_vlan_add(struct net_device *pdev, unsigned short pkey) rtnl_unlock(); mutex_unlock(&ppriv->sysfs_mutex); - if (result) { + if (result && priv) { free_netdev(priv->dev); kfree(priv); } @@ -204,7 +207,12 @@ int ipoib_vlan_delete(struct net_device *pdev, unsigned short pkey) return restart_syscall(); } - down_write(&ppriv->vlan_rwsem); + if (!down_write_trylock(&ppriv->vlan_rwsem)) { + rtnl_unlock(); + mutex_unlock(&ppriv->sysfs_mutex); + return restart_syscall(); + } + list_for_each_entry_safe(priv, tpriv, &ppriv->child_intfs, list) { if (priv->pkey == pkey && priv->child_type == IPOIB_LEGACY_CHILD) {