cxgb4: Fix race condition in cleanup

There is a possible race condition when we unregister the PCI Driver and then
flush/destroy the global "workq". This could lead to situations where there
are tasks on the Work Queue with references to now deleted adapter data
structures. Instead, have per-adapter Work Queues which were instantiated and
torn down in init_one() and remove_one(), respectively.

v2: Remove unnecessary call to flush_workqueue() before destroy_workqueue()

Signed-off-by: Anish Bhatt <anish@chelsio.com>
Signed-off-by: Casey Leedom <leedom@chelsio.com>
Acked-by: Neil Horman <nhorman@tuxdriver.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/drivers/net/ethernet/chelsio/cxgb4/cxgb4.h b/drivers/net/ethernet/chelsio/cxgb4/cxgb4.h
index d572821..c067b78 100644 (file)
--- a/drivers/net/ethernet/chelsio/cxgb4/cxgb4.h
+++ b/drivers/net/ethernet/chelsio/cxgb4/cxgb4.h
@@ -652,6 +652,7 @@ struct adapter {
        struct tid_info tids;
        void **tid_release_head;
        spinlock_t tid_release_lock;
+       struct workqueue_struct *workq;
        struct work_struct tid_release_task;
        struct work_struct db_full_task;
        struct work_struct db_drop_task;

diff --git a/drivers/net/ethernet/chelsio/cxgb4/cxgb4_main.c b/drivers/net/ethernet/chelsio/cxgb4/cxgb4_main.c
index 1afee70..18fb9c6 100644 (file)
--- a/drivers/net/ethernet/chelsio/cxgb4/cxgb4_main.c
+++ b/drivers/net/ethernet/chelsio/cxgb4/cxgb4_main.c
@@ -643,8 +643,6 @@ static int set_rxmode(struct net_device *dev, int mtu, bool sleep_ok)
        return ret;
 }
 
-static struct workqueue_struct *workq;
-
 /**
  *     link_start - enable a port
  *     @dev: the port to enable
@@ -3340,7 +3338,7 @@ static void cxgb4_queue_tid_release(struct tid_info *t, unsigned int chan,
        adap->tid_release_head = (void **)((uintptr_t)p | chan);
        if (!adap->tid_release_task_busy) {
                adap->tid_release_task_busy = true;
-               queue_work(workq, &adap->tid_release_task);
+               queue_work(adap->workq, &adap->tid_release_task);
        }
        spin_unlock_bh(&adap->tid_release_lock);
 }
@@ -4140,7 +4138,7 @@ void t4_db_full(struct adapter *adap)
                notify_rdma_uld(adap, CXGB4_CONTROL_DB_FULL);
                t4_set_reg_field(adap, SGE_INT_ENABLE3,
                                 DBFIFO_HP_INT | DBFIFO_LP_INT, 0);
-               queue_work(workq, &adap->db_full_task);
+               queue_work(adap->workq, &adap->db_full_task);
        }
 }
 
@@ -4150,7 +4148,7 @@ void t4_db_dropped(struct adapter *adap)
                disable_dbs(adap);
                notify_rdma_uld(adap, CXGB4_CONTROL_DB_FULL);
        }
-       queue_work(workq, &adap->db_drop_task);
+       queue_work(adap->workq, &adap->db_drop_task);
 }
 
 static void uld_attach(struct adapter *adap, unsigned int uld)
@@ -6517,6 +6515,12 @@ static int init_one(struct pci_dev *pdev, const struct pci_device_id *ent)
                goto out_disable_device;
        }
 
+       adapter->workq = create_singlethread_workqueue("cxgb4");
+       if (!adapter->workq) {
+               err = -ENOMEM;
+               goto out_free_adapter;
+       }
+
        /* PCI device has been enabled */
        adapter->flags |= DEV_ENABLED;
 
@@ -6715,6 +6719,9 @@ sriov:
  out_unmap_bar0:
        iounmap(adapter->regs);
  out_free_adapter:
+       if (adapter->workq)
+               destroy_workqueue(adapter->workq);
+
        kfree(adapter);
  out_disable_device:
        pci_disable_pcie_error_reporting(pdev);
@@ -6736,6 +6743,11 @@ static void remove_one(struct pci_dev *pdev)
        if (adapter) {
                int i;
 
+               /* Tear down per-adapter Work Queue first since it can contain
+                * references to our adapter data structure.
+                */
+               destroy_workqueue(adapter->workq);
+
                if (is_offload(adapter))
                        detach_ulds(adapter);
 
@@ -6788,20 +6800,14 @@ static int __init cxgb4_init_module(void)
 {
        int ret;
 
-       workq = create_singlethread_workqueue("cxgb4");
-       if (!workq)
-               return -ENOMEM;
-
        /* Debugfs support is optional, just warn if this fails */
        cxgb4_debugfs_root = debugfs_create_dir(KBUILD_MODNAME, NULL);
        if (!cxgb4_debugfs_root)
                pr_warn("could not create debugfs entry, continuing\n");
 
        ret = pci_register_driver(&cxgb4_driver);
-       if (ret < 0) {
+       if (ret < 0)
                debugfs_remove(cxgb4_debugfs_root);
-               destroy_workqueue(workq);
-       }
 
        register_inet6addr_notifier(&cxgb4_inet6addr_notifier);
 
@@ -6813,8 +6819,6 @@ static void __exit cxgb4_cleanup_module(void)
        unregister_inet6addr_notifier(&cxgb4_inet6addr_notifier);
        pci_unregister_driver(&cxgb4_driver);
        debugfs_remove(cxgb4_debugfs_root);  /* NULL ok */
-       flush_workqueue(workq);
-       destroy_workqueue(workq);
 }
 
 module_init(cxgb4_init_module);