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path: root/drivers/char/virtio_console.c
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Diffstat (limited to 'drivers/char/virtio_console.c')
-rw-r--r--drivers/char/virtio_console.c17
1 files changed, 14 insertions, 3 deletions
diff --git a/drivers/char/virtio_console.c b/drivers/char/virtio_console.c
index c810481a5bc..0f69c5ec0ec 100644
--- a/drivers/char/virtio_console.c
+++ b/drivers/char/virtio_console.c
@@ -459,9 +459,12 @@ static ssize_t send_buf(struct port *port, void *in_buf, size_t in_count,
/*
* Wait till the host acknowledges it pushed out the data we
- * sent. This is done for ports in blocking mode or for data
- * from the hvc_console; the tty operations are performed with
- * spinlocks held so we can't sleep here.
+ * sent. This is done for data from the hvc_console; the tty
+ * operations are performed with spinlocks held so we can't
+ * sleep here. An alternative would be to copy the data to a
+ * buffer and relax the spinning requirement. The downside is
+ * we need to kmalloc a GFP_ATOMIC buffer each time the
+ * console driver writes something out.
*/
while (!virtqueue_get_buf(out_vq, &len))
cpu_relax();
@@ -626,6 +629,14 @@ static ssize_t port_fops_write(struct file *filp, const char __user *ubuf,
goto free_buf;
}
+ /*
+ * We now ask send_buf() to not spin for generic ports -- we
+ * can re-use the same code path that non-blocking file
+ * descriptors take for blocking file descriptors since the
+ * wait is already done and we're certain the write will go
+ * through to the host.
+ */
+ nonblock = true;
ret = send_buf(port, buf, count, nonblock);
if (nonblock && ret > 0)