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authorJason Gunthorpe <jgg@mellanox.com>2018-07-29 11:34:57 +0300
committerJason Gunthorpe <jgg@mellanox.com>2018-08-02 20:27:43 -0600
commitee190ab734ba4d3c7887bd193ce8124385738e44 (patch)
tree53ebb12de34e3032a59e0e19dde5bdfe42a5b503 /drivers/infiniband
parent9f49a5b5c21d58aa84e16cfdc5e99e49faefcb7a (diff)
downloadlinux-ee190ab734ba4d3c7887bd193ce8124385738e44.tar.bz2
IB/ipoib: Get rid of the sysfs_mutex
This mutex was introduced to deal with the deadlock formed by calling unregister_netdev from within the sysfs callback of a netdev. Now that we have priv_destructor and needs_free_netdev we can switch to the more targeted solution of running the unregister from a work queue. This avoids the deadlock and gets rid of the mutex. The next patch in the series needs this mutex eliminated to create atomicity of unregisteration. Signed-off-by: Jason Gunthorpe <jgg@mellanox.com> Signed-off-by: Leon Romanovsky <leonro@mellanox.com>
Diffstat (limited to 'drivers/infiniband')
-rw-r--r--drivers/infiniband/ulp/ipoib/ipoib.h1
-rw-r--r--drivers/infiniband/ulp/ipoib/ipoib_cm.c7
-rw-r--r--drivers/infiniband/ulp/ipoib/ipoib_main.c7
-rw-r--r--drivers/infiniband/ulp/ipoib/ipoib_vlan.c98
4 files changed, 65 insertions, 48 deletions
diff --git a/drivers/infiniband/ulp/ipoib/ipoib.h b/drivers/infiniband/ulp/ipoib/ipoib.h
index d2cb0a8500e3..804cb4bee57d 100644
--- a/drivers/infiniband/ulp/ipoib/ipoib.h
+++ b/drivers/infiniband/ulp/ipoib/ipoib.h
@@ -332,7 +332,6 @@ struct ipoib_dev_priv {
struct rw_semaphore vlan_rwsem;
struct mutex mcast_mutex;
- struct mutex sysfs_mutex;
struct rb_root path_tree;
struct list_head path_list;
diff --git a/drivers/infiniband/ulp/ipoib/ipoib_cm.c b/drivers/infiniband/ulp/ipoib/ipoib_cm.c
index 16ea08dc59a8..ea01b8dd2be6 100644
--- a/drivers/infiniband/ulp/ipoib/ipoib_cm.c
+++ b/drivers/infiniband/ulp/ipoib/ipoib_cm.c
@@ -1517,19 +1517,13 @@ 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 = ipoib_priv(dev);
-
- if (!mutex_trylock(&priv->sysfs_mutex))
- return restart_syscall();
if (!rtnl_trylock()) {
- mutex_unlock(&priv->sysfs_mutex);
return restart_syscall();
}
if (dev->reg_state != NETREG_REGISTERED) {
rtnl_unlock();
- mutex_unlock(&priv->sysfs_mutex);
return -EPERM;
}
@@ -1541,7 +1535,6 @@ static ssize_t set_mode(struct device *d, struct device_attribute *attr,
*/
if (ret != -EBUSY)
rtnl_unlock();
- mutex_unlock(&priv->sysfs_mutex);
return (!ret || ret == -EBUSY) ? count : ret;
}
diff --git a/drivers/infiniband/ulp/ipoib/ipoib_main.c b/drivers/infiniband/ulp/ipoib/ipoib_main.c
index 73d917d57f93..e9f4f261fe20 100644
--- a/drivers/infiniband/ulp/ipoib/ipoib_main.c
+++ b/drivers/infiniband/ulp/ipoib/ipoib_main.c
@@ -2079,7 +2079,6 @@ static void ipoib_build_priv(struct net_device *dev)
spin_lock_init(&priv->lock);
init_rwsem(&priv->vlan_rwsem);
mutex_init(&priv->mcast_mutex);
- mutex_init(&priv->sysfs_mutex);
INIT_LIST_HEAD(&priv->path_list);
INIT_LIST_HEAD(&priv->child_intfs);
@@ -2476,10 +2475,7 @@ static void ipoib_remove_one(struct ib_device *device, void *client_data)
list_for_each_entry_safe(priv, tmp, dev_list, list) {
ipoib_parent_unregister_pre(priv->dev);
- /* Wrap rtnl_lock/unlock with mutex to protect sysfs calls */
- mutex_lock(&priv->sysfs_mutex);
unregister_netdev(priv->dev);
- mutex_unlock(&priv->sysfs_mutex);
}
kfree(dev_list);
@@ -2527,8 +2523,7 @@ static int __init ipoib_init_module(void)
* its private workqueue, and we only queue up flush events
* on our global flush workqueue. This avoids the deadlocks.
*/
- ipoib_workqueue = alloc_ordered_workqueue("ipoib_flush",
- WQ_MEM_RECLAIM);
+ ipoib_workqueue = alloc_ordered_workqueue("ipoib_flush", 0);
if (!ipoib_workqueue) {
ret = -ENOMEM;
goto err_fs;
diff --git a/drivers/infiniband/ulp/ipoib/ipoib_vlan.c b/drivers/infiniband/ulp/ipoib/ipoib_vlan.c
index 7776334cf8c5..891c5b40018a 100644
--- a/drivers/infiniband/ulp/ipoib/ipoib_vlan.c
+++ b/drivers/infiniband/ulp/ipoib/ipoib_vlan.c
@@ -125,23 +125,16 @@ int ipoib_vlan_add(struct net_device *pdev, unsigned short pkey)
snprintf(intf_name, sizeof(intf_name), "%s.%04x",
ppriv->dev->name, pkey);
- if (!mutex_trylock(&ppriv->sysfs_mutex))
+ if (!rtnl_trylock())
return restart_syscall();
- if (!rtnl_trylock()) {
- mutex_unlock(&ppriv->sysfs_mutex);
- return restart_syscall();
- }
-
if (pdev->reg_state != NETREG_REGISTERED) {
rtnl_unlock();
- mutex_unlock(&ppriv->sysfs_mutex);
return -EPERM;
}
if (!down_write_trylock(&ppriv->vlan_rwsem)) {
rtnl_unlock();
- mutex_unlock(&ppriv->sysfs_mutex);
return restart_syscall();
}
@@ -178,58 +171,95 @@ int ipoib_vlan_add(struct net_device *pdev, unsigned short pkey)
out:
up_write(&ppriv->vlan_rwsem);
rtnl_unlock();
- mutex_unlock(&ppriv->sysfs_mutex);
return result;
}
+struct ipoib_vlan_delete_work {
+ struct work_struct work;
+ struct net_device *dev;
+};
+
+/*
+ * sysfs callbacks of a netdevice cannot obtain the rtnl lock as
+ * unregister_netdev ultimately deletes the sysfs files while holding the rtnl
+ * lock. This deadlocks the system.
+ *
+ * A callback can use rtnl_trylock to avoid the deadlock but it cannot call
+ * unregister_netdev as that internally takes and releases the rtnl_lock. So
+ * instead we find the netdev to unregister and then do the actual unregister
+ * from the global work queue where we can obtain the rtnl_lock safely.
+ */
+static void ipoib_vlan_delete_task(struct work_struct *work)
+{
+ struct ipoib_vlan_delete_work *pwork =
+ container_of(work, struct ipoib_vlan_delete_work, work);
+ struct net_device *dev = pwork->dev;
+
+ rtnl_lock();
+
+ /* Unregistering tasks can race with another task or parent removal */
+ if (dev->reg_state == NETREG_REGISTERED) {
+ struct ipoib_dev_priv *priv = ipoib_priv(dev);
+ struct ipoib_dev_priv *ppriv = ipoib_priv(priv->parent);
+
+ down_write(&ppriv->vlan_rwsem);
+ list_del(&priv->list);
+ up_write(&ppriv->vlan_rwsem);
+
+ ipoib_dbg(ppriv, "delete child vlan %s\n", dev->name);
+ unregister_netdevice(dev);
+ }
+
+ rtnl_unlock();
+
+ kfree(pwork);
+}
+
int ipoib_vlan_delete(struct net_device *pdev, unsigned short pkey)
{
struct ipoib_dev_priv *ppriv, *priv, *tpriv;
- struct net_device *dev = NULL;
+ int rc;
if (!capable(CAP_NET_ADMIN))
return -EPERM;
- ppriv = ipoib_priv(pdev);
-
- if (!mutex_trylock(&ppriv->sysfs_mutex))
+ if (!rtnl_trylock())
return restart_syscall();
- if (!rtnl_trylock()) {
- mutex_unlock(&ppriv->sysfs_mutex);
- return restart_syscall();
- }
-
if (pdev->reg_state != NETREG_REGISTERED) {
rtnl_unlock();
- mutex_unlock(&ppriv->sysfs_mutex);
return -EPERM;
}
- if (!down_write_trylock(&ppriv->vlan_rwsem)) {
- rtnl_unlock();
- mutex_unlock(&ppriv->sysfs_mutex);
- return restart_syscall();
- }
+ ppriv = ipoib_priv(pdev);
+ rc = -ENODEV;
list_for_each_entry_safe(priv, tpriv, &ppriv->child_intfs, list) {
if (priv->pkey == pkey &&
priv->child_type == IPOIB_LEGACY_CHILD) {
- list_del(&priv->list);
- dev = priv->dev;
+ struct ipoib_vlan_delete_work *work;
+
+ work = kmalloc(sizeof(*work), GFP_KERNEL);
+ if (!work) {
+ rc = -ENOMEM;
+ goto out;
+ }
+
+ down_write(&ppriv->vlan_rwsem);
+ list_del_init(&priv->list);
+ up_write(&ppriv->vlan_rwsem);
+ work->dev = priv->dev;
+ INIT_WORK(&work->work, ipoib_vlan_delete_task);
+ queue_work(ipoib_workqueue, &work->work);
+
+ rc = 0;
break;
}
}
- up_write(&ppriv->vlan_rwsem);
-
- if (dev) {
- ipoib_dbg(ppriv, "delete child vlan %s\n", dev->name);
- unregister_netdevice(dev);
- }
+out:
rtnl_unlock();
- mutex_unlock(&ppriv->sysfs_mutex);
- return (dev) ? 0 : -ENODEV;
+ return rc;
}