Merge tag 'fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/rusty/linux

Pull virtio fixes from Rusty Russell:
 "More virtio console fixes than I'm happy with, but all real issues,
  and all CC:stable.."

* tag 'fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/rusty/linux:
  virtio-scsi: Fix virtqueue affinity setup
  virtio: console: return -ENODEV on all read operations after unplug
  virtio: console: fix raising SIGIO after port unplug
  virtio: console: clean up port data immediately at time of unplug
  virtio: console: fix race in port_fops_open() and port unplug
  virtio: console: fix race with port unplug and open/close
  virtio/console: Add pipe_lock/unlock for splice_write
  virtio/console: Quit from splice_write if pipe->nrbufs is 0

1 files changed, 48 insertions, 22 deletions

diff --git a/drivers/char/virtio_console.c b/drivers/char/virtio_console.c
index 1b456fe9b87a..fc45567ad3ac 100644
--- a/drivers/char/virtio_console.c
+++ b/drivers/char/virtio_console.c
@@ -272,9 +272,12 @@ static struct port *find_port_by_devt_in_portdev(struct ports_device *portdev,
         unsigned long flags;
 
         spin_lock_irqsave(&portdev->ports_lock, flags);
-        list_for_each_entry(port, &portdev->ports, list)
-                if (port->cdev->dev == dev)
+        list_for_each_entry(port, &portdev->ports, list) {
+                if (port->cdev->dev == dev) {
+                        kref_get(&port->kref);
                         goto out;
+                }
+        }
         port = NULL;
 out:
         spin_unlock_irqrestore(&portdev->ports_lock, flags);
@@ -746,6 +749,10 @@ static ssize_t port_fops_read(struct file *filp, char __user *ubuf,
 
         port = filp->private_data;
 
+        /* Port is hot-unplugged. */
+        if (!port->guest_connected)
+                return -ENODEV;
+
         if (!port_has_data(port)) {
                 /*
                  * If nothing's connected on the host just return 0 in
@@ -762,7 +769,7 @@ static ssize_t port_fops_read(struct file *filp, char __user *ubuf,
                 if (ret < 0)
                         return ret;
         }
-        /* Port got hot-unplugged. */
+        /* Port got hot-unplugged while we were waiting above. */
         if (!port->guest_connected)
                 return -ENODEV;
         /*
@@ -932,13 +939,25 @@ static ssize_t port_fops_splice_write(struct pipe_inode_info *pipe,
         if (is_rproc_serial(port->out_vq->vdev))
                 return -EINVAL;
 
+        /*
+         * pipe->nrbufs == 0 means there are no data to transfer,
+         * so this returns just 0 for no data.
+         */
+        pipe_lock(pipe);
+        if (!pipe->nrbufs) {
+                ret = 0;
+                goto error_out;
+        }
+
         ret = wait_port_writable(port, filp->f_flags & O_NONBLOCK);
         if (ret < 0)
-                return ret;
+                goto error_out;
 
         buf = alloc_buf(port->out_vq, 0, pipe->nrbufs);
-        if (!buf)
-                return -ENOMEM;
+        if (!buf) {
+                ret = -ENOMEM;
+                goto error_out;
+        }
 
         sgl.n = 0;
         sgl.len = 0;
@@ -946,12 +965,17 @@ static ssize_t port_fops_splice_write(struct pipe_inode_info *pipe,
         sgl.sg = buf->sg;
         sg_init_table(sgl.sg, sgl.size);
         ret = __splice_from_pipe(pipe, &sd, pipe_to_sg);
+        pipe_unlock(pipe);
         if (likely(ret > 0))
                 ret = __send_to_port(port, buf->sg, sgl.n, sgl.len, buf, true);
 
         if (unlikely(ret <= 0))
                 free_buf(buf, true);
         return ret;
+
+error_out:
+        pipe_unlock(pipe);
+        return ret;
 }
 
 static unsigned int port_fops_poll(struct file *filp, poll_table *wait)
@@ -1019,14 +1043,14 @@ static int port_fops_open(struct inode *inode, struct file *filp)
         struct port *port;
         int ret;
 
+        /* We get the port with a kref here */
         port = find_port_by_devt(cdev->dev);
+        if (!port) {
+                /* Port was unplugged before we could proceed */
+                return -ENXIO;
+        }
         filp->private_data = port;
 
-        /* Prevent against a port getting hot-unplugged at the same time */
-        spin_lock_irq(&port->portdev->ports_lock);
-        kref_get(&port->kref);
-        spin_unlock_irq(&port->portdev->ports_lock);
-
         /*
          * Don't allow opening of console port devices -- that's done
          * via /dev/hvc
@@ -1498,14 +1522,6 @@ static void remove_port(struct kref *kref)
 
         port = container_of(kref, struct port, kref);
 
-        sysfs_remove_group(&port->dev->kobj, &port_attribute_group);
-        device_destroy(pdrvdata.class, port->dev->devt);
-        cdev_del(port->cdev);
-
-        kfree(port->name);
-
-        debugfs_remove(port->debugfs_file);
-
         kfree(port);
 }
 
@@ -1539,12 +1555,14 @@ static void unplug_port(struct port *port)
         spin_unlock_irq(&port->portdev->ports_lock);
 
         if (port->guest_connected) {
+                /* Let the app know the port is going down. */
+                send_sigio_to_port(port);
+
+                /* Do this after sigio is actually sent */
                 port->guest_connected = false;
                 port->host_connected = false;
-                wake_up_interruptible(&port->waitqueue);
 
-                /* Let the app know the port is going down. */
-                send_sigio_to_port(port);
+                wake_up_interruptible(&port->waitqueue);
         }
 
         if (is_console_port(port)) {
@@ -1563,6 +1581,14 @@ static void unplug_port(struct port *port)
          */
         port->portdev = NULL;
 
+        sysfs_remove_group(&port->dev->kobj, &port_attribute_group);
+        device_destroy(pdrvdata.class, port->dev->devt);
+        cdev_del(port->cdev);
+
+        kfree(port->name);
+
+        debugfs_remove(port->debugfs_file);
+
         /*
          * Locks around here are not necessary - a port can't be
          * opened after we removed the port struct from ports_list