From 198b12f77084244d310888dd5d643083cb5c2aa1 Mon Sep 17 00:00:00 2001 From: Erez Shitrit Date: Sat, 4 Jun 2016 15:15:20 +0300 Subject: [PATCH] IB/IPoIB: Fix race between ipoib_remove_one to sysfs functions In ipoib_remove_one the driver holds the rtnl_lock and tries to do some operation like dev_change_flags or unregister_netdev, while sysfs callback like ipoib_vlan_delete holds sysfs mutex and tries to hold the rtnl_lock via rtnl_trylock() and restart_syscall() if the lock is not free, meanwhile ipoib_remove_one tries to get the sysfs lock in order to free its sysfs directory, and we will get a->b, b->a deadlock. Trace like the following: schedule+0x37/0x80 schedule_preempt_disabled+0xe/0x10 __mutex_lock_slowpath+0xb5/0x120 mutex_lock+0x23/0x40 rtnl_lock+0x15/0x20 netdev_run_todo+0x17c/0x320 rtnl_unlock+0xe/0x10 ipoib_vlan_delete+0x11b/0x1b0 [ib_ipoib] delete_child+0x54/0x80 [ib_ipoib] dev_attr_store+0x18/0x30 sysfs_kf_write+0x37/0x40 mutex_lock+0x16/0x40 SyS_write+0x55/0xc0 entry_SYSCALL_64_fastpath+0x16/0x75 And schedule+0x37/0x80 __kernfs_remove+0x1a8/0x260 ? wake_atomic_t_function+0x60/0x60 kernfs_remove+0x25/0x40 sysfs_remove_dir+0x50/0x80 kobject_del+0x18/0x50 device_del+0x19f/0x260 netdev_unregister_kobject+0x6a/0x80 rollback_registered_many+0x1fd/0x340 rollback_registered+0x3c/0x70 unregister_netdevice_queue+0x55/0xc0 unregister_netdev+0x20/0x30 ipoib_remove_one+0x114/0x1b0 [ib_ipoib] ib_unregister_client+0x4a/0x170 [ib_core] ? find_module_all+0x71/0xa0 ipoib_cleanup_module+0x10/0x94 [ib_ipoib] SyS_delete_module+0x1b5/0x210 entry_SYSCALL_64_fastpath+0x16/0x75 The fix is by checking the flag IPOIB_FLAG_INTF_ON_DESTROY in order to get out from the sysfs function. Fixes: 862096a8bbf8 ("IB/ipoib: Add more rtnl_link_ops callbacks") Fixes: 9baa0b036410 ("IB/ipoib: Add rtnl_link_ops support") Signed-off-by: Erez Shitrit Signed-off-by: Leon Romanovsky Signed-off-by: Doug Ledford --- drivers/infiniband/ulp/ipoib/ipoib.h | 1 + drivers/infiniband/ulp/ipoib/ipoib_cm.c | 4 ++++ drivers/infiniband/ulp/ipoib/ipoib_main.c | 3 +++ drivers/infiniband/ulp/ipoib/ipoib_vlan.c | 6 ++++++ 4 files changed, 14 insertions(+) diff --git a/drivers/infiniband/ulp/ipoib/ipoib.h b/drivers/infiniband/ulp/ipoib/ipoib.h index bab7db6fa9ab..4f7d9b48df64 100644 --- a/drivers/infiniband/ulp/ipoib/ipoib.h +++ b/drivers/infiniband/ulp/ipoib/ipoib.h @@ -94,6 +94,7 @@ enum { IPOIB_NEIGH_TBL_FLUSH = 12, IPOIB_FLAG_DEV_ADDR_SET = 13, IPOIB_FLAG_DEV_ADDR_CTRL = 14, + IPOIB_FLAG_GOING_DOWN = 15, IPOIB_MAX_BACKOFF_SECONDS = 16, diff --git a/drivers/infiniband/ulp/ipoib/ipoib_cm.c b/drivers/infiniband/ulp/ipoib/ipoib_cm.c index b2f42835d76d..951d9abcca8b 100644 --- a/drivers/infiniband/ulp/ipoib/ipoib_cm.c +++ b/drivers/infiniband/ulp/ipoib/ipoib_cm.c @@ -1486,6 +1486,10 @@ static ssize_t set_mode(struct device *d, struct device_attribute *attr, { struct net_device *dev = to_net_dev(d); int ret; + struct ipoib_dev_priv *priv = netdev_priv(dev); + + if (test_bit(IPOIB_FLAG_GOING_DOWN, &priv->flags)) + return -EPERM; if (!rtnl_trylock()) return restart_syscall(); diff --git a/drivers/infiniband/ulp/ipoib/ipoib_main.c b/drivers/infiniband/ulp/ipoib/ipoib_main.c index 2d7c16346648..0aa52c2f9438 100644 --- a/drivers/infiniband/ulp/ipoib/ipoib_main.c +++ b/drivers/infiniband/ulp/ipoib/ipoib_main.c @@ -2141,6 +2141,9 @@ static void ipoib_remove_one(struct ib_device *device, void *client_data) ib_unregister_event_handler(&priv->event_handler); flush_workqueue(ipoib_workqueue); + /* mark interface in the middle of destruction */ + set_bit(IPOIB_FLAG_GOING_DOWN, &priv->flags); + rtnl_lock(); dev_change_flags(priv->dev, priv->dev->flags & ~IFF_UP); rtnl_unlock(); diff --git a/drivers/infiniband/ulp/ipoib/ipoib_vlan.c b/drivers/infiniband/ulp/ipoib/ipoib_vlan.c index 64a35595eab8..a2f9f29c6ab5 100644 --- a/drivers/infiniband/ulp/ipoib/ipoib_vlan.c +++ b/drivers/infiniband/ulp/ipoib/ipoib_vlan.c @@ -131,6 +131,9 @@ int ipoib_vlan_add(struct net_device *pdev, unsigned short pkey) ppriv = netdev_priv(pdev); + if (test_bit(IPOIB_FLAG_GOING_DOWN, &ppriv->flags)) + return -EPERM; + snprintf(intf_name, sizeof intf_name, "%s.%04x", ppriv->dev->name, pkey); priv = ipoib_intf_alloc(intf_name); @@ -183,6 +186,9 @@ int ipoib_vlan_delete(struct net_device *pdev, unsigned short pkey) ppriv = netdev_priv(pdev); + if (test_bit(IPOIB_FLAG_GOING_DOWN, &ppriv->flags)) + return -EPERM; + if (!rtnl_trylock()) return restart_syscall(); -- 2.20.1