RDS: Rewrite connection cleanup, fixing oops on rmmod

This fixes a bug where a connection was unexpectedly
not on *any* list while being destroyed. It also
cleans up some code duplication and regularizes some
function names.

* Grab appropriate lock in conn_free() and explain in comment
* Ensure via locking that a conn is never not on either
  a dev's list or the nodev list
* Add rds_xx_remove_conn() to match rds_xx_add_conn()
* Make rds_xx_add_conn() return void
* Rename remove_{,nodev_}conns() to
  destroy_{,nodev_}conns() and unify their implementation
  in a helper function
* Document lock ordering as nodev conn_lock before
  dev_conn_lock

Reported-by: Yosef Etigin <yosefe@voltaire.com>
Signed-off-by: Andy Grover <andy.grover@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

8 files changed, 109 insertions, 85 deletions

diff --git a/net/rds/ib.c b/net/rds/ib.c
index 06a7b798d9a7..4933b380985e 100644
--- a/net/rds/ib.c
+++ b/net/rds/ib.c
@@ -51,6 +51,7 @@ MODULE_PARM_DESC(fmr_message_size, " Max size of a RDMA transfer");
 
 struct list_head rds_ib_devices;
 
+/* NOTE: if also grabbing ibdev lock, grab this first */
 DEFINE_SPINLOCK(ib_nodev_conns_lock);
 LIST_HEAD(ib_nodev_conns);
 
@@ -137,7 +138,7 @@ void rds_ib_remove_one(struct ib_device *device)
                 kfree(i_ipaddr);
         }
 
-        rds_ib_remove_conns(rds_ibdev);
+        rds_ib_destroy_conns(rds_ibdev);
 
         if (rds_ibdev->mr_pool)
                 rds_ib_destroy_mr_pool(rds_ibdev->mr_pool);
@@ -249,7 +250,7 @@ static int rds_ib_laddr_check(__be32 addr)
 void rds_ib_exit(void)
 {
         rds_info_deregister_func(RDS_INFO_IB_CONNECTIONS, rds_ib_ic_info);
-        rds_ib_remove_nodev_conns();
+        rds_ib_destroy_nodev_conns();
         ib_unregister_client(&rds_ib_client);
         rds_ib_sysctl_exit();
         rds_ib_recv_exit();
diff --git a/net/rds/ib.h b/net/rds/ib.h
index 8be563a1363a..c08ffffb3164 100644
--- a/net/rds/ib.h
+++ b/net/rds/ib.h
@@ -267,9 +267,17 @@ void rds_ib_cm_connect_complete(struct rds_connection *conn,
 
 /* ib_rdma.c */
 int rds_ib_update_ipaddr(struct rds_ib_device *rds_ibdev, __be32 ipaddr);
-int rds_ib_add_conn(struct rds_ib_device *rds_ibdev, struct rds_connection *conn);
-void rds_ib_remove_nodev_conns(void);
-void rds_ib_remove_conns(struct rds_ib_device *rds_ibdev);
+void rds_ib_add_conn(struct rds_ib_device *rds_ibdev, struct rds_connection *conn);
+void rds_ib_remove_conn(struct rds_ib_device *rds_ibdev, struct rds_connection *conn);
+void __rds_ib_destroy_conns(struct list_head *list, spinlock_t *list_lock);
+static inline void rds_ib_destroy_nodev_conns(void)
+{
+        __rds_ib_destroy_conns(&ib_nodev_conns, &ib_nodev_conns_lock);
+}
+static inline void rds_ib_destroy_conns(struct rds_ib_device *rds_ibdev)
+{
+        __rds_ib_destroy_conns(&rds_ibdev->conn_list, &rds_ibdev->spinlock);
+}
 struct rds_ib_mr_pool *rds_ib_create_mr_pool(struct rds_ib_device *);
 void rds_ib_get_mr_info(struct rds_ib_device *rds_ibdev, struct rds_info_rdma_connection *iinfo);
 void rds_ib_destroy_mr_pool(struct rds_ib_mr_pool *);
diff --git a/net/rds/ib_cm.c b/net/rds/ib_cm.c
index 0532237bd128..889ab0441359 100644
--- a/net/rds/ib_cm.c
+++ b/net/rds/ib_cm.c
@@ -126,9 +126,7 @@ void rds_ib_cm_connect_complete(struct rds_connection *conn, struct rdma_cm_even
         err = rds_ib_update_ipaddr(rds_ibdev, conn->c_laddr);
         if (err)
                 printk(KERN_ERR "rds_ib_update_ipaddr failed (%d)\n", err);
-        err = rds_ib_add_conn(rds_ibdev, conn);
-        if (err)
-                printk(KERN_ERR "rds_ib_add_conn failed (%d)\n", err);
+        rds_ib_add_conn(rds_ibdev, conn);
 
         /* If the peer gave us the last packet it saw, process this as if
          * we had received a regular ACK. */
@@ -616,18 +614,8 @@ void rds_ib_conn_shutdown(struct rds_connection *conn)
                 /*
                  * Move connection back to the nodev list.
                  */
-                if (ic->rds_ibdev) {
-
-                        spin_lock_irq(&ic->rds_ibdev->spinlock);
-                        BUG_ON(list_empty(&ic->ib_node));
-                        list_del(&ic->ib_node);
-                        spin_unlock_irq(&ic->rds_ibdev->spinlock);
-
-                        spin_lock_irq(&ib_nodev_conns_lock);
-                        list_add_tail(&ic->ib_node, &ib_nodev_conns);
-                        spin_unlock_irq(&ib_nodev_conns_lock);
-                        ic->rds_ibdev = NULL;
-                }
+                if (ic->rds_ibdev)
+                        rds_ib_remove_conn(ic->rds_ibdev, conn);
 
                 ic->i_cm_id = NULL;
                 ic->i_pd = NULL;
@@ -701,11 +689,27 @@ int rds_ib_conn_alloc(struct rds_connection *conn, gfp_t gfp)
         return 0;
 }
 
+/*
+ * Free a connection. Connection must be shut down and not set for reconnect.
+ */
 void rds_ib_conn_free(void *arg)
 {
         struct rds_ib_connection *ic = arg;
+        spinlock_t      *lock_ptr;
+
         rdsdebug("ic %p\n", ic);
+
+        /*
+         * Conn is either on a dev's list or on the nodev list.
+         * A race with shutdown() or connect() would cause problems
+         * (since rds_ibdev would change) but that should never happen.
+         */
+        lock_ptr = ic->rds_ibdev ? &ic->rds_ibdev->spinlock : &ib_nodev_conns_lock;
+
+        spin_lock_irq(lock_ptr);
         list_del(&ic->ib_node);
+        spin_unlock_irq(lock_ptr);
+
         kfree(ic);
 }
 
diff --git a/net/rds/ib_rdma.c b/net/rds/ib_rdma.c
index 69a6289ed672..81033af93020 100644
--- a/net/rds/ib_rdma.c
+++ b/net/rds/ib_rdma.c
@@ -139,7 +139,7 @@ int rds_ib_update_ipaddr(struct rds_ib_device *rds_ibdev, __be32 ipaddr)
         return rds_ib_add_ipaddr(rds_ibdev, ipaddr);
 }
 
-int rds_ib_add_conn(struct rds_ib_device *rds_ibdev, struct rds_connection *conn)
+void rds_ib_add_conn(struct rds_ib_device *rds_ibdev, struct rds_connection *conn)
 {
         struct rds_ib_connection *ic = conn->c_transport_data;
 
@@ -148,45 +148,44 @@ int rds_ib_add_conn(struct rds_ib_device *rds_ibdev, struct rds_connection *conn
         BUG_ON(list_empty(&ib_nodev_conns));
         BUG_ON(list_empty(&ic->ib_node));
         list_del(&ic->ib_node);
-        spin_unlock_irq(&ib_nodev_conns_lock);
 
         spin_lock_irq(&rds_ibdev->spinlock);
         list_add_tail(&ic->ib_node, &rds_ibdev->conn_list);
         spin_unlock_irq(&rds_ibdev->spinlock);
+        spin_unlock_irq(&ib_nodev_conns_lock);
 
         ic->rds_ibdev = rds_ibdev;
-
-        return 0;
 }
 
-void rds_ib_remove_nodev_conns(void)
+void rds_ib_remove_conn(struct rds_ib_device *rds_ibdev, struct rds_connection *conn)
 {
-        struct rds_ib_connection *ic, *_ic;
-        LIST_HEAD(tmp_list);
+        struct rds_ib_connection *ic = conn->c_transport_data;
 
-        /* avoid calling conn_destroy with irqs off */
-        spin_lock_irq(&ib_nodev_conns_lock);
-        list_splice(&ib_nodev_conns, &tmp_list);
-        INIT_LIST_HEAD(&ib_nodev_conns);
-        spin_unlock_irq(&ib_nodev_conns_lock);
+        /* place conn on nodev_conns_list */
+        spin_lock(&ib_nodev_conns_lock);
 
-        list_for_each_entry_safe(ic, _ic, &tmp_list, ib_node) {
-                if (ic->conn->c_passive)
-                        rds_conn_destroy(ic->conn->c_passive);
-                rds_conn_destroy(ic->conn);
-        }
+        spin_lock_irq(&rds_ibdev->spinlock);
+        BUG_ON(list_empty(&ic->ib_node));
+        list_del(&ic->ib_node);
+        spin_unlock_irq(&rds_ibdev->spinlock);
+
+        list_add_tail(&ic->ib_node, &ib_nodev_conns);
+
+        spin_unlock(&ib_nodev_conns_lock);
+
+        ic->rds_ibdev = NULL;
 }
 
-void rds_ib_remove_conns(struct rds_ib_device *rds_ibdev)
+void __rds_ib_destroy_conns(struct list_head *list, spinlock_t *list_lock)
 {
         struct rds_ib_connection *ic, *_ic;
         LIST_HEAD(tmp_list);
 
         /* avoid calling conn_destroy with irqs off */
-        spin_lock_irq(&rds_ibdev->spinlock);
-        list_splice(&rds_ibdev->conn_list, &tmp_list);
-        INIT_LIST_HEAD(&rds_ibdev->conn_list);
-        spin_unlock_irq(&rds_ibdev->spinlock);
+        spin_lock_irq(list_lock);
+        list_splice(list, &tmp_list);
+        INIT_LIST_HEAD(list);
+        spin_unlock_irq(list_lock);
 
         list_for_each_entry_safe(ic, _ic, &tmp_list, ib_node) {
                 if (ic->conn->c_passive)
diff --git a/net/rds/iw.c b/net/rds/iw.c
index 1b56905c4c08..b732efb5b634 100644
--- a/net/rds/iw.c
+++ b/net/rds/iw.c
@@ -51,6 +51,7 @@ MODULE_PARM_DESC(fastreg_message_size, " Max size of a RDMA transfer (fastreg MR
 
 struct list_head rds_iw_devices;
 
+/* NOTE: if also grabbing iwdev lock, grab this first */
 DEFINE_SPINLOCK(iw_nodev_conns_lock);
 LIST_HEAD(iw_nodev_conns);
 
@@ -145,7 +146,7 @@ void rds_iw_remove_one(struct ib_device *device)
         }
         spin_unlock_irq(&rds_iwdev->spinlock);
 
-        rds_iw_remove_conns(rds_iwdev);
+        rds_iw_destroy_conns(rds_iwdev);
 
         if (rds_iwdev->mr_pool)
                 rds_iw_destroy_mr_pool(rds_iwdev->mr_pool);
@@ -258,7 +259,7 @@ static int rds_iw_laddr_check(__be32 addr)
 void rds_iw_exit(void)
 {
         rds_info_deregister_func(RDS_INFO_IWARP_CONNECTIONS, rds_iw_ic_info);
-        rds_iw_remove_nodev_conns();
+        rds_iw_destroy_nodev_conns();
         ib_unregister_client(&rds_iw_client);
         rds_iw_sysctl_exit();
         rds_iw_recv_exit();
diff --git a/net/rds/iw.h b/net/rds/iw.h
index 0ddda34f2a1c..70eb948f42f4 100644
--- a/net/rds/iw.h
+++ b/net/rds/iw.h
@@ -294,9 +294,17 @@ void rds_iw_cm_connect_complete(struct rds_connection *conn,
 
 /* ib_rdma.c */
 int rds_iw_update_cm_id(struct rds_iw_device *rds_iwdev, struct rdma_cm_id *cm_id);
-int rds_iw_add_conn(struct rds_iw_device *rds_iwdev, struct rds_connection *conn);
-void rds_iw_remove_nodev_conns(void);
-void rds_iw_remove_conns(struct rds_iw_device *rds_iwdev);
+void rds_iw_add_conn(struct rds_iw_device *rds_iwdev, struct rds_connection *conn);
+void rds_iw_remove_conn(struct rds_iw_device *rds_iwdev, struct rds_connection *conn);
+void __rds_iw_destroy_conns(struct list_head *list, spinlock_t *list_lock);
+static inline void rds_iw_destroy_nodev_conns(void)
+{
+        __rds_iw_destroy_conns(&iw_nodev_conns, &iw_nodev_conns_lock);
+}
+static inline void rds_iw_destroy_conns(struct rds_iw_device *rds_iwdev)
+{
+        __rds_iw_destroy_conns(&rds_iwdev->conn_list, &rds_iwdev->spinlock);
+}
 struct rds_iw_mr_pool *rds_iw_create_mr_pool(struct rds_iw_device *);
 void rds_iw_get_mr_info(struct rds_iw_device *rds_iwdev, struct rds_info_rdma_connection *iinfo);
 void rds_iw_destroy_mr_pool(struct rds_iw_mr_pool *);
diff --git a/net/rds/iw_cm.c b/net/rds/iw_cm.c
index 57ecb3d4b8a5..0ffaa3e97ad6 100644
--- a/net/rds/iw_cm.c
+++ b/net/rds/iw_cm.c
@@ -86,9 +86,7 @@ void rds_iw_cm_connect_complete(struct rds_connection *conn, struct rdma_cm_even
         err = rds_iw_update_cm_id(rds_iwdev, ic->i_cm_id);
         if (err)
                 printk(KERN_ERR "rds_iw_update_ipaddr failed (%d)\n", err);
-        err = rds_iw_add_conn(rds_iwdev, conn);
-        if (err)
-                printk(KERN_ERR "rds_iw_add_conn failed (%d)\n", err);
+        rds_iw_add_conn(rds_iwdev, conn);
 
         /* If the peer gave us the last packet it saw, process this as if
          * we had received a regular ACK. */
@@ -637,19 +635,8 @@ void rds_iw_conn_shutdown(struct rds_connection *conn)
                  *      Move connection back to the nodev list.
                  *      Remove cm_id from the device cm_id list.
                  */
-                if (ic->rds_iwdev) {
-
-                        spin_lock_irq(&ic->rds_iwdev->spinlock);
-                        BUG_ON(list_empty(&ic->iw_node));
-                        list_del(&ic->iw_node);
-                        spin_unlock_irq(&ic->rds_iwdev->spinlock);
-
-                        spin_lock_irq(&iw_nodev_conns_lock);
-                        list_add_tail(&ic->iw_node, &iw_nodev_conns);
-                        spin_unlock_irq(&iw_nodev_conns_lock);
-                        rds_iw_remove_cm_id(ic->rds_iwdev, ic->i_cm_id);
-                        ic->rds_iwdev = NULL;
-                }
+                if (ic->rds_iwdev)
+                        rds_iw_remove_conn(ic->rds_iwdev, conn);
 
                 rdma_destroy_id(ic->i_cm_id);
 
@@ -726,11 +713,27 @@ int rds_iw_conn_alloc(struct rds_connection *conn, gfp_t gfp)
         return 0;
 }
 
+/*
+ * Free a connection. Connection must be shut down and not set for reconnect.
+ */
 void rds_iw_conn_free(void *arg)
 {
         struct rds_iw_connection *ic = arg;
+        spinlock_t      *lock_ptr;
+
         rdsdebug("ic %p\n", ic);
+
+        /*
+         * Conn is either on a dev's list or on the nodev list.
+         * A race with shutdown() or connect() would cause problems
+         * (since rds_iwdev would change) but that should never happen.
+         */
+        lock_ptr = ic->rds_iwdev ? &ic->rds_iwdev->spinlock : &iw_nodev_conns_lock;
+
+        spin_lock_irq(lock_ptr);
         list_del(&ic->iw_node);
+        spin_unlock_irq(lock_ptr);
+
         kfree(ic);
 }
 
diff --git a/net/rds/iw_rdma.c b/net/rds/iw_rdma.c
index 1c02a8f952d0..dcdb37da80f2 100644
--- a/net/rds/iw_rdma.c
+++ b/net/rds/iw_rdma.c
@@ -196,7 +196,7 @@ int rds_iw_update_cm_id(struct rds_iw_device *rds_iwdev, struct rdma_cm_id *cm_i
         return rds_iw_add_cm_id(rds_iwdev, cm_id);
 }
 
-int rds_iw_add_conn(struct rds_iw_device *rds_iwdev, struct rds_connection *conn)
+void rds_iw_add_conn(struct rds_iw_device *rds_iwdev, struct rds_connection *conn)
 {
         struct rds_iw_connection *ic = conn->c_transport_data;
 
@@ -205,45 +205,45 @@ int rds_iw_add_conn(struct rds_iw_device *rds_iwdev, struct rds_connection *conn
         BUG_ON(list_empty(&iw_nodev_conns));
         BUG_ON(list_empty(&ic->iw_node));
         list_del(&ic->iw_node);
-        spin_unlock_irq(&iw_nodev_conns_lock);
 
         spin_lock_irq(&rds_iwdev->spinlock);
         list_add_tail(&ic->iw_node, &rds_iwdev->conn_list);
         spin_unlock_irq(&rds_iwdev->spinlock);
+        spin_unlock_irq(&iw_nodev_conns_lock);
 
         ic->rds_iwdev = rds_iwdev;
-
-        return 0;
 }
 
-void rds_iw_remove_nodev_conns(void)
+void rds_iw_remove_conn(struct rds_iw_device *rds_iwdev, struct rds_connection *conn)
 {
-        struct rds_iw_connection *ic, *_ic;
-        LIST_HEAD(tmp_list);
+        struct rds_iw_connection *ic = conn->c_transport_data;
 
-        /* avoid calling conn_destroy with irqs off */
-        spin_lock_irq(&iw_nodev_conns_lock);
-        list_splice(&iw_nodev_conns, &tmp_list);
-        INIT_LIST_HEAD(&iw_nodev_conns);
-        spin_unlock_irq(&iw_nodev_conns_lock);
+        /* place conn on nodev_conns_list */
+        spin_lock(&iw_nodev_conns_lock);
 
-        list_for_each_entry_safe(ic, _ic, &tmp_list, iw_node) {
-                if (ic->conn->c_passive)
-                        rds_conn_destroy(ic->conn->c_passive);
-                rds_conn_destroy(ic->conn);
-        }
+        spin_lock_irq(&rds_iwdev->spinlock);
+        BUG_ON(list_empty(&ic->iw_node));
+        list_del(&ic->iw_node);
+        spin_unlock_irq(&rds_iwdev->spinlock);
+
+        list_add_tail(&ic->iw_node, &iw_nodev_conns);
+
+        spin_unlock(&iw_nodev_conns_lock);
+
+        rds_iw_remove_cm_id(ic->rds_iwdev, ic->i_cm_id);
+        ic->rds_iwdev = NULL;
 }
 
-void rds_iw_remove_conns(struct rds_iw_device *rds_iwdev)
+void __rds_iw_destroy_conns(struct list_head *list, spinlock_t *list_lock)
 {
         struct rds_iw_connection *ic, *_ic;
         LIST_HEAD(tmp_list);
 
         /* avoid calling conn_destroy with irqs off */
-        spin_lock_irq(&rds_iwdev->spinlock);
-        list_splice(&rds_iwdev->conn_list, &tmp_list);
-        INIT_LIST_HEAD(&rds_iwdev->conn_list);
-        spin_unlock_irq(&rds_iwdev->spinlock);
+        spin_lock_irq(list_lock);
+        list_splice(list, &tmp_list);
+        INIT_LIST_HEAD(list);
+        spin_unlock_irq(list_lock);
 
         list_for_each_entry_safe(ic, _ic, &tmp_list, iw_node) {
                 if (ic->conn->c_passive)