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-rw-r--r--Documentation/lguest/lguest.c17
1 files changed, 16 insertions, 1 deletions
diff --git a/Documentation/lguest/lguest.c b/Documentation/lguest/lguest.c
index 20f8253881b..64110797044 100644
--- a/Documentation/lguest/lguest.c
+++ b/Documentation/lguest/lguest.c
@@ -769,6 +769,16 @@ static void net_output(struct virtqueue *vq)
add_used(vq, head, 0);
}
+/* Will reading from this file descriptor block? */
+static bool will_block(int fd)
+{
+ fd_set fdset;
+ struct timeval zero = { 0, 0 };
+ FD_ZERO(&fdset);
+ FD_SET(fd, &fdset);
+ return select(fd+1, &fdset, NULL, NULL, &zero) != 1;
+}
+
/* This is where we handle packets coming in from the tun device to our
* Guest. */
static void net_input(struct virtqueue *vq)
@@ -781,10 +791,15 @@ static void net_input(struct virtqueue *vq)
head = wait_for_vq_desc(vq, iov, &out, &in);
if (out)
errx(1, "Output buffers in net input queue?");
+
+ /* Deliver interrupt now, since we're about to sleep. */
+ if (vq->pending_used && will_block(net_info->tunfd))
+ trigger_irq(vq);
+
len = readv(net_info->tunfd, iov, in);
if (len <= 0)
err(1, "Failed to read from tun.");
- add_used_and_trigger(vq, head, len);
+ add_used(vq, head, len);
}
/* This is the helper to create threads. */