[Qemu-devel] [RFC PATCH 3/6] virtio/console: Wait until the port is ready on splice

[Yoshihiro YUNOMAE]

From: Masami Hiramatsu <address@hidden>

Wait if the port is not connected or full on splice
like as write is doing.

Signed-off-by: Masami Hiramatsu <address@hidden>
Cc: Amit Shah <address@hidden>
Cc: Arnd Bergmann <address@hidden>
Cc: Greg Kroah-Hartman <address@hidden>
---

 drivers/char/virtio_console.c |   39 +++++++++++++++++++++++++++------------
 1 files changed, 27 insertions(+), 12 deletions(-)

diff --git a/drivers/char/virtio_console.c b/drivers/char/virtio_console.c
index 911cb3e..e49d435 100644
--- a/drivers/char/virtio_console.c
+++ b/drivers/char/virtio_console.c
@@ -724,6 +724,26 @@ static ssize_t port_fops_read(struct file *filp, char 
__user *ubuf,
        return fill_readbuf(port, ubuf, count, true);
 }
 
+static int wait_port_writable(struct port *port, bool nonblock)
+{
+       int ret;
+
+       if (will_write_block(port)) {
+               if (nonblock)
+                       return -EAGAIN;
+
+               ret = wait_event_freezable(port->waitqueue,
+                                          !will_write_block(port));
+               if (ret < 0)
+                       return ret;
+       }
+       /* Port got hot-unplugged. */
+       if (!port->guest_connected)
+               return -ENODEV;
+
+       return 0;
+}
+
 static ssize_t port_fops_write(struct file *filp, const char __user *ubuf,
                               size_t count, loff_t *offp)
 {
@@ -740,18 +760,9 @@ static ssize_t port_fops_write(struct file *filp, const 
char __user *ubuf,
 
        nonblock = filp->f_flags & O_NONBLOCK;
 
-       if (will_write_block(port)) {
-               if (nonblock)
-                       return -EAGAIN;
-
-               ret = wait_event_freezable(port->waitqueue,
-                                          !will_write_block(port));
-               if (ret < 0)
-                       return ret;
-       }
-       /* Port got hot-unplugged. */
-       if (!port->guest_connected)
-               return -ENODEV;
+       ret = wait_port_writable(port, nonblock);
+       if (ret < 0)
+               return ret;
 
        count = min((size_t)(32 * 1024), count);
 
@@ -851,6 +862,10 @@ static ssize_t port_fops_splice_write(struct 
pipe_inode_info *pipe,
                .u.data = &sgl,
        };
 
+       ret = wait_port_writable(port, filp->f_flags & O_NONBLOCK);
+       if (ret < 0)
+               return ret;
+
        sgl.n = 0;
        sgl.len = 0;
        sgl.sg = kmalloc(sizeof(struct scatterlist) * MAX_SPLICE_PAGES,