cnic: Fix locking in start/stop calls.

The slow path ulp_start and ulp_stop calls to the bnx2i driver
are sleepable calls and therefore should not be protected using
rcu_read_lock.  Fix it by using mutex and setting a bit during
these calls.  cnic_unregister_device() will now wait for the bit
to clear before completing the call.

Signed-off-by: Michael Chan <mchan@broadcom.com>
Reviewed-by: Benjamin Li <benli@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 28 insertions, 16 deletions

diff --git a/drivers/net/cnic.c b/drivers/net/cnic.c
index 2db81f0e4f72..4ff618a7afd2 100644
--- a/drivers/net/cnic.c
+++ b/drivers/net/cnic.c
@@ -466,6 +466,7 @@ EXPORT_SYMBOL(cnic_register_driver);
 static int cnic_unregister_device(struct cnic_dev *dev, int ulp_type)
 {
         struct cnic_local *cp = dev->cnic_priv;
+        int i = 0;
 
         if (ulp_type >= MAX_CNIC_ULP_TYPE) {
                 printk(KERN_ERR PFX "cnic_unregister_device: Bad type %d\n",
@@ -486,6 +487,15 @@ static int cnic_unregister_device(struct cnic_dev *dev, int ulp_type)
 
         synchronize_rcu();
 
+        while (test_bit(ULP_F_CALL_PENDING, &cp->ulp_flags[ulp_type]) &&
+               i < 20) {
+                msleep(100);
+                i++;
+        }
+        if (test_bit(ULP_F_CALL_PENDING, &cp->ulp_flags[ulp_type]))
+                printk(KERN_WARNING PFX "%s: Failed waiting for ULP up call"
+                                        " to complete.\n", dev->netdev->name);
+
         return 0;
 }
 EXPORT_SYMBOL(cnic_unregister_driver);
@@ -1076,18 +1086,23 @@ static void cnic_ulp_stop(struct cnic_dev *dev)
         if (cp->cnic_uinfo)
                 cnic_send_nlmsg(cp, ISCSI_KEVENT_IF_DOWN, NULL);
 
-        rcu_read_lock();
         for (if_type = 0; if_type < MAX_CNIC_ULP_TYPE; if_type++) {
                 struct cnic_ulp_ops *ulp_ops;
 
-                ulp_ops = rcu_dereference(cp->ulp_ops[if_type]);
-                if (!ulp_ops)
+                mutex_lock(&cnic_lock);
+                ulp_ops = cp->ulp_ops[if_type];
+                if (!ulp_ops) {
+                        mutex_unlock(&cnic_lock);
                         continue;
+                }
+                set_bit(ULP_F_CALL_PENDING, &cp->ulp_flags[if_type]);
+                mutex_unlock(&cnic_lock);
 
                 if (test_and_clear_bit(ULP_F_START, &cp->ulp_flags[if_type]))
                         ulp_ops->cnic_stop(cp->ulp_handle[if_type]);
+
+                clear_bit(ULP_F_CALL_PENDING, &cp->ulp_flags[if_type]);
         }
-        rcu_read_unlock();
 }
 
 static void cnic_ulp_start(struct cnic_dev *dev)
@@ -1095,18 +1110,23 @@ static void cnic_ulp_start(struct cnic_dev *dev)
         struct cnic_local *cp = dev->cnic_priv;
         int if_type;
 
-        rcu_read_lock();
         for (if_type = 0; if_type < MAX_CNIC_ULP_TYPE; if_type++) {
                 struct cnic_ulp_ops *ulp_ops;
 
-                ulp_ops = rcu_dereference(cp->ulp_ops[if_type]);
-                if (!ulp_ops || !ulp_ops->cnic_start)
+                mutex_lock(&cnic_lock);
+                ulp_ops = cp->ulp_ops[if_type];
+                if (!ulp_ops || !ulp_ops->cnic_start) {
+                        mutex_unlock(&cnic_lock);
                         continue;
+                }
+                set_bit(ULP_F_CALL_PENDING, &cp->ulp_flags[if_type]);
+                mutex_unlock(&cnic_lock);
 
                 if (!test_and_set_bit(ULP_F_START, &cp->ulp_flags[if_type]))
                         ulp_ops->cnic_start(cp->ulp_handle[if_type]);
+
+                clear_bit(ULP_F_CALL_PENDING, &cp->ulp_flags[if_type]);
         }
-        rcu_read_unlock();
 }
 
 static int cnic_ctl(void *data, struct cnic_ctl_info *info)
@@ -1116,22 +1136,18 @@ static int cnic_ctl(void *data, struct cnic_ctl_info *info)
         switch (info->cmd) {
         case CNIC_CTL_STOP_CMD:
                 cnic_hold(dev);
-                mutex_lock(&cnic_lock);
 
                 cnic_ulp_stop(dev);
                 cnic_stop_hw(dev);
 
-                mutex_unlock(&cnic_lock);
                 cnic_put(dev);
                 break;
         case CNIC_CTL_START_CMD:
                 cnic_hold(dev);
-                mutex_lock(&cnic_lock);
 
                 if (!cnic_start_hw(dev))
                         cnic_ulp_start(dev);
 
-                mutex_unlock(&cnic_lock);
                 cnic_put(dev);
                 break;
         default:
@@ -2667,10 +2683,8 @@ static int cnic_netdev_event(struct notifier_block *this, unsigned long event,
                                 cnic_put(dev);
                                 goto done;
                         }
-                        mutex_lock(&cnic_lock);
                         if (!cnic_start_hw(dev))
                                 cnic_ulp_start(dev);
-                        mutex_unlock(&cnic_lock);
                 }
 
                 rcu_read_lock();
@@ -2689,10 +2703,8 @@ static int cnic_netdev_event(struct notifier_block *this, unsigned long event,
                 rcu_read_unlock();
 
                 if (event == NETDEV_GOING_DOWN) {
-                        mutex_lock(&cnic_lock);
                         cnic_ulp_stop(dev);
                         cnic_stop_hw(dev);
-                        mutex_unlock(&cnic_lock);
                         cnic_unregister_netdev(dev);
                 } else if (event == NETDEV_UNREGISTER) {
                         write_lock(&cnic_dev_lock);