[PATCH rdma-rc 3/7] IB/IPoIB: Fix race between ipoib_remove_one to sysfs functions

Leon Romanovsky
2016-06-04T12:15:20Z

From: Erez Shitrit <erezsh-VPRAkNaXOzVWk0Htik3J/w@public.gmane.org>

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 <erezsh-VPRAkNaXOzVWk0Htik3J/w@public.gmane.org>
Signed-off-by: Leon Romanovsky <leon-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>
---
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 bab7db6..4f7d9b4 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 b2f4283..951d9ab 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 c558c32..1cd569f 100644
--- a/drivers/infiniband/ulp/ipoib/ipoib_main.c
+++ b/drivers/infiniband/ulp/ipoib/ipoib_main.c
@@ -2143,6 +2143,9 @@ 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 64a3559..a2f9f29 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();

--
2.1.4