[PATCH AUTOSEL 4.19 49/68] net/ibmnvic: Fix deadlock problem in reset

Sasha Levin
2018-11-29T05:59:54Z

From: Juliet Kim <julietk@linux.vnet.ibm.com>

[ Upstream commit a5681e20b541a507c7d4fd48ae4a4040d32ee1ef ]

This patch changes to use rtnl_lock only during a reset to avoid
deadlock that could occur when a thread operating close is holding
rtnl_lock and waiting for reset_lock acquired by another thread,
which is waiting for rtnl_lock in order to set the number of tx/rx
queues during a reset.

Also, we now setting the number of tx/rx queues during a soft reset
for failover or LPM events.

Signed-off-by: Juliet Kim <julietk@linux.vnet.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/net/ethernet/ibm/ibmvnic.c | 59 +++++++++++-------------------
drivers/net/ethernet/ibm/ibmvnic.h | 2 +-
2 files changed, 22 insertions(+), 39 deletions(-)

diff --git a/drivers/net/ethernet/ibm/ibmvnic.c b/drivers/net/ethernet/ibm/ibmvnic.c
index 7661064c815b..a646de07cbdc 100644
--- a/drivers/net/ethernet/ibm/ibmvnic.c
+++ b/drivers/net/ethernet/ibm/ibmvnic.c
@@ -1103,20 +1103,15 @@ static int ibmvnic_open(struct net_device *netdev)
return 0;
}

- mutex_lock(&adapter->reset_lock);
-
if (adapter->state != VNIC_CLOSED) {
rc = ibmvnic_login(netdev);
- if (rc) {
- mutex_unlock(&adapter->reset_lock);
+ if (rc)
return rc;
- }

rc = init_resources(adapter);
if (rc) {
netdev_err(netdev, "failed to initialize resources\n");
release_resources(adapter);
- mutex_unlock(&adapter->reset_lock);
return rc;
}
}
@@ -1124,8 +1119,6 @@ static int ibmvnic_open(struct net_device *netdev)
rc = __ibmvnic_open(netdev);
netif_carrier_on(netdev);

- mutex_unlock(&adapter->reset_lock);
-
return rc;
}

@@ -1269,10 +1262,8 @@ static int ibmvnic_close(struct net_device *netdev)
return 0;
}

- mutex_lock(&adapter->reset_lock);
rc = __ibmvnic_close(netdev);
ibmvnic_cleanup(netdev);
- mutex_unlock(&adapter->reset_lock);

return rc;
}
@@ -1820,20 +1811,15 @@ static int do_reset(struct ibmvnic_adapter *adapter,
return rc;
} else if (adapter->req_rx_queues != old_num_rx_queues ||
adapter->req_tx_queues != old_num_tx_queues) {
- adapter->map_id = 1;
release_rx_pools(adapter);
release_tx_pools(adapter);
- rc = init_rx_pools(netdev);
- if (rc)
- return rc;
- rc = init_tx_pools(netdev);
- if (rc)
- return rc;
-
release_napi(adapter);
- rc = init_napi(adapter);
+ release_vpd_data(adapter);
+
+ rc = init_resources(adapter);
if (rc)
return rc;
+
} else {
rc = reset_tx_pools(adapter);
if (rc)
@@ -1917,17 +1903,8 @@ static int do_hard_reset(struct ibmvnic_adapter *adapter,
adapter->state = VNIC_PROBED;
return 0;
}
- /* netif_set_real_num_xx_queues needs to take rtnl lock here
- * unless wait_for_reset is set, in which case the rtnl lock
- * has already been taken before initializing the reset
- */
- if (!adapter->wait_for_reset) {
- rtnl_lock();
- rc = init_resources(adapter);
- rtnl_unlock();
- } else {
- rc = init_resources(adapter);
- }
+
+ rc = init_resources(adapter);
if (rc)
return rc;

@@ -1986,13 +1963,21 @@ static void __ibmvnic_reset(struct work_struct *work)
struct ibmvnic_rwi *rwi;
struct ibmvnic_adapter *adapter;
struct net_device *netdev;
+ bool we_lock_rtnl = false;
u32 reset_state;
int rc = 0;

adapter = container_of(work, struct ibmvnic_adapter, ibmvnic_reset);
netdev = adapter->netdev;

- mutex_lock(&adapter->reset_lock);
+ /* netif_set_real_num_xx_queues needs to take rtnl lock here
+ * unless wait_for_reset is set, in which case the rtnl lock
+ * has already been taken before initializing the reset
+ */
+ if (!adapter->wait_for_reset) {
+ rtnl_lock();
+ we_lock_rtnl = true;
+ }
reset_state = adapter->state;

rwi = get_next_rwi(adapter);
@@ -2020,12 +2005,11 @@ static void __ibmvnic_reset(struct work_struct *work)
if (rc) {
netdev_dbg(adapter->netdev, "Reset failed\n");
free_all_rwi(adapter);
- mutex_unlock(&adapter->reset_lock);
- return;
}

adapter->resetting = false;
- mutex_unlock(&adapter->reset_lock);
+ if (we_lock_rtnl)
+ rtnl_unlock();
}

static int ibmvnic_reset(struct ibmvnic_adapter *adapter,
@@ -4709,7 +4693,6 @@ static int ibmvnic_probe(struct vio_dev *dev, const struct vio_device_id *id)

INIT_WORK(&adapter->ibmvnic_reset, __ibmvnic_reset);
INIT_LIST_HEAD(&adapter->rwi_list);
- mutex_init(&adapter->reset_lock);
mutex_init(&adapter->rwi_lock);
adapter->resetting = false;

@@ -4781,8 +4764,8 @@ static int ibmvnic_remove(struct vio_dev *dev)
struct ibmvnic_adapter *adapter = netdev_priv(netdev);

adapter->state = VNIC_REMOVING;
- unregister_netdev(netdev);
- mutex_lock(&adapter->reset_lock);
+ rtnl_lock();
+ unregister_netdevice(netdev);

release_resources(adapter);
release_sub_crqs(adapter, 1);
@@ -4793,7 +4776,7 @@ static int ibmvnic_remove(struct vio_dev *dev)

adapter->state = VNIC_REMOVED;

- mutex_unlock(&adapter->reset_lock);
+ rtnl_unlock();
device_remove_file(&dev->dev, &dev_attr_failover);
free_netdev(netdev);
dev_set_drvdata(&dev->dev, NULL);
diff --git a/drivers/net/ethernet/ibm/ibmvnic.h b/drivers/net/ethernet/ibm/ibmvnic.h
index f06eec145ca6..735f481b1870 100644
--- a/drivers/net/ethernet/ibm/ibmvnic.h
+++ b/drivers/net/ethernet/ibm/ibmvnic.h
@@ -1068,7 +1068,7 @@ struct ibmvnic_adapter {
struct tasklet_struct tasklet;
enum vnic_state state;
enum ibmvnic_reset_reason reset_reason;
- struct mutex reset_lock, rwi_lock;
+ struct mutex rwi_lock;
struct list_head rwi_list;
struct work_struct ibmvnic_reset;
bool resetting;
--
2.17.1