From ba4de7fd43bb21be634a39b0de274cfb9b19fd83 Mon Sep 17 00:00:00 2001 From: Hans de Goede Date: Thu, 16 Sep 2010 14:43:08 +0530 Subject: [PATCH] virtio: console: Fix poll blocking even though there is data to read commit 6df7aadcd9290807c464675098b5dd2dc9da5075 upstream. I found this while working on a Linux agent for spice, the symptom I was seeing was select blocking on the spice vdagent virtio serial port even though there were messages queued up there. virtio_console's port_fops_poll checks port->inbuf != NULL to determine if read won't block. However if an application reads enough bytes from inbuf through port_fops_read, to empty the current port->inbuf, port->inbuf will be NULL even though there may be buffers left in the virtqueue. This causes poll() to block even though there is data to be read, this patch fixes this by using will_read_block(port) instead of the port->inbuf != NULL check. Signed-off-By: Hans de Goede Signed-off-by: Amit Shah Signed-off-by: Rusty Russell Signed-off-by: Greg Kroah-Hartman --- drivers/char/virtio_console.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/char/virtio_console.c b/drivers/char/virtio_console.c index 56ffd0d93e253..c810481a5bc23 100644 --- a/drivers/char/virtio_console.c +++ b/drivers/char/virtio_console.c @@ -646,7 +646,7 @@ static unsigned int port_fops_poll(struct file *filp, poll_table *wait) poll_wait(filp, &port->waitqueue, wait); ret = 0; - if (port->inbuf) + if (!will_read_block(port)) ret |= POLLIN | POLLRDNORM; if (!will_write_block(port)) ret |= POLLOUT; -- 2.47.3