[IB] umad: fix hot remove of IB devices

Fix hotplug of devices for ib_umad module: when a device goes away,
kill off all MAD agents for open files associated with that device,
and make sure that the device is not touched again after ib_umad
returns from its remove_one function.

Signed-off-by: Roland Dreier <rolandd@cisco.com>

diff --git a/drivers/infiniband/core/user_mad.c b/drivers/infiniband/core/user_mad.c
index 97128e2..aed5ca2 100644 (file)
--- a/drivers/infiniband/core/user_mad.c
+++ b/drivers/infiniband/core/user_mad.c
@@ -94,6 +94,9 @@ struct ib_umad_port {
        struct class_device   *sm_class_dev;
        struct semaphore       sm_sem;
 
+       struct rw_semaphore    mutex;
+       struct list_head       file_list;
+
        struct ib_device      *ib_dev;
        struct ib_umad_device *umad_dev;
        int                    dev_num;
@@ -108,10 +111,10 @@ struct ib_umad_device {
 
 struct ib_umad_file {
        struct ib_umad_port *port;
-       spinlock_t           recv_lock;
        struct list_head     recv_list;
+       struct list_head     port_list;
+       spinlock_t           recv_lock;
        wait_queue_head_t    recv_wait;
-       struct rw_semaphore  agent_mutex;
        struct ib_mad_agent *agent[IB_UMAD_MAX_AGENTS];
        struct ib_mr        *mr[IB_UMAD_MAX_AGENTS];
 };
@@ -148,7 +151,7 @@ static int queue_packet(struct ib_umad_file *file,
 {
        int ret = 1;
 
-       down_read(&file->agent_mutex);
+       down_read(&file->port->mutex);
        for (packet->mad.hdr.id = 0;
             packet->mad.hdr.id < IB_UMAD_MAX_AGENTS;
             packet->mad.hdr.id++)
@@ -161,7 +164,7 @@ static int queue_packet(struct ib_umad_file *file,
                        break;
                }
 
-       up_read(&file->agent_mutex);
+       up_read(&file->port->mutex);
 
        return ret;
 }
@@ -322,7 +325,7 @@ static ssize_t ib_umad_write(struct file *filp, const char __user *buf,
                goto err;
        }
 
-       down_read(&file->agent_mutex);
+       down_read(&file->port->mutex);
 
        agent = file->agent[packet->mad.hdr.id];
        if (!agent) {
@@ -419,7 +422,7 @@ static ssize_t ib_umad_write(struct file *filp, const char __user *buf,
        if (ret)
                goto err_msg;
 
-       up_read(&file->agent_mutex);
+       up_read(&file->port->mutex);
 
        return count;
 
@@ -430,7 +433,7 @@ err_ah:
        ib_destroy_ah(ah);
 
 err_up:
-       up_read(&file->agent_mutex);
+       up_read(&file->port->mutex);
 
 err:
        kfree(packet);
@@ -460,7 +463,12 @@ static int ib_umad_reg_agent(struct ib_umad_file *file, unsigned long arg)
        int agent_id;
        int ret;
 
-       down_write(&file->agent_mutex);
+       down_write(&file->port->mutex);
+
+       if (!file->port->ib_dev) {
+               ret = -EPIPE;
+               goto out;
+       }
 
        if (copy_from_user(&ureq, (void __user *) arg, sizeof ureq)) {
                ret = -EFAULT;
@@ -522,7 +530,7 @@ err:
        ib_unregister_mad_agent(agent);
 
 out:
-       up_write(&file->agent_mutex);
+       up_write(&file->port->mutex);
        return ret;
 }
 
@@ -531,7 +539,7 @@ static int ib_umad_unreg_agent(struct ib_umad_file *file, unsigned long arg)
        u32 id;
        int ret = 0;
 
-       down_write(&file->agent_mutex);
+       down_write(&file->port->mutex);
 
        if (get_user(id, (u32 __user *) arg)) {
                ret = -EFAULT;
@@ -548,7 +556,7 @@ static int ib_umad_unreg_agent(struct ib_umad_file *file, unsigned long arg)
        file->agent[id] = NULL;
 
 out:
-       up_write(&file->agent_mutex);
+       up_write(&file->port->mutex);
        return ret;
 }
 
@@ -569,6 +577,7 @@ static int ib_umad_open(struct inode *inode, struct file *filp)
 {
        struct ib_umad_port *port;
        struct ib_umad_file *file;
+       int ret = 0;
 
        spin_lock(&port_lock);
        port = umad_port[iminor(inode) - IB_UMAD_MINOR_BASE];
@@ -579,21 +588,32 @@ static int ib_umad_open(struct inode *inode, struct file *filp)
        if (!port)
                return -ENXIO;
 
+       down_write(&port->mutex);
+
+       if (!port->ib_dev) {
+               ret = -ENXIO;
+               goto out;
+       }
+
        file = kzalloc(sizeof *file, GFP_KERNEL);
        if (!file) {
                kref_put(&port->umad_dev->ref, ib_umad_release_dev);
-               return -ENOMEM;
+               ret = -ENOMEM;
+               goto out;
        }
 
        spin_lock_init(&file->recv_lock);
-       init_rwsem(&file->agent_mutex);
        INIT_LIST_HEAD(&file->recv_list);
        init_waitqueue_head(&file->recv_wait);
 
        file->port = port;
        filp->private_data = file;
 
-       return 0;
+       list_add_tail(&file->port_list, &port->file_list);
+
+out:
+       up_write(&port->mutex);
+       return ret;
 }
 
 static int ib_umad_close(struct inode *inode, struct file *filp)
@@ -603,6 +623,7 @@ static int ib_umad_close(struct inode *inode, struct file *filp)
        struct ib_umad_packet *packet, *tmp;
        int i;
 
+       down_write(&file->port->mutex);
        for (i = 0; i < IB_UMAD_MAX_AGENTS; ++i)
                if (file->agent[i]) {
                        ib_dereg_mr(file->mr[i]);
@@ -612,6 +633,9 @@ static int ib_umad_close(struct inode *inode, struct file *filp)
        list_for_each_entry_safe(packet, tmp, &file->recv_list, list)
                kfree(packet);
 
+       list_del(&file->port_list);
+       up_write(&file->port->mutex);
+
        kfree(file);
 
        kref_put(&dev->ref, ib_umad_release_dev);
@@ -680,9 +704,13 @@ static int ib_umad_sm_close(struct inode *inode, struct file *filp)
        struct ib_port_modify props = {
                .clr_port_cap_mask = IB_PORT_SM
        };
-       int ret;
+       int ret = 0;
+
+       down_write(&port->mutex);
+       if (port->ib_dev)
+               ret = ib_modify_port(port->ib_dev, port->port_num, 0, &props);
+       up_write(&port->mutex);
 
-       ret = ib_modify_port(port->ib_dev, port->port_num, 0, &props);
        up(&port->sm_sem);
 
        kref_put(&port->umad_dev->ref, ib_umad_release_dev);
@@ -745,6 +773,8 @@ static int ib_umad_init_port(struct ib_device *device, int port_num,
        port->ib_dev   = device;
        port->port_num = port_num;
        init_MUTEX(&port->sm_sem);
+       init_rwsem(&port->mutex);
+       INIT_LIST_HEAD(&port->file_list);
 
        port->dev = cdev_alloc();
        if (!port->dev)
@@ -813,6 +843,9 @@ err_cdev:
 
 static void ib_umad_kill_port(struct ib_umad_port *port)
 {
+       struct ib_umad_file *file;
+       int id;
+
        class_set_devdata(port->class_dev,    NULL);
        class_set_devdata(port->sm_class_dev, NULL);
 
@@ -826,6 +859,21 @@ static void ib_umad_kill_port(struct ib_umad_port *port)
        umad_port[port->dev_num] = NULL;
        spin_unlock(&port_lock);
 
+       down_write(&port->mutex);
+
+       port->ib_dev = NULL;
+
+       list_for_each_entry(file, &port->file_list, port_list)
+               for (id = 0; id < IB_UMAD_MAX_AGENTS; ++id) {
+                       if (!file->agent[id])
+                               continue;
+                       ib_dereg_mr(file->mr[id]);
+                       ib_unregister_mad_agent(file->agent[id]);
+                       file->agent[id] = NULL;
+               }
+
+       up_write(&port->mutex);
+
        clear_bit(port->dev_num, dev_map);
 }