virtio: clarify NO_NOTIFY flag usage

[linux-2.6-omap-h63xx.git] / Documentation / lguest / lguest.c

diff --git a/Documentation/lguest/lguest.c b/Documentation/lguest/lguest.c
index 4df1804169dc9dcda03c65dee5d604ca2cbcbf91..8ff2d8bc690a7feac35effca2593c354891ecb78 100644 (file)
--- a/Documentation/lguest/lguest.c
+++ b/Documentation/lguest/lguest.c
@@ -923,10 +923,10 @@ static void handle_output(int fd, unsigned long addr)
        /* Check each virtqueue. */
        for (i = devices.dev; i; i = i->next) {
                for (vq = i->vq; vq; vq = vq->next) {
-                       if (vq->config.pfn == addr/getpagesize()
-                           && vq->handle_output) {
+                       if (vq->config.pfn == addr/getpagesize()) {
                                verbose("Output to %s\n", vq->dev->name);
-                               vq->handle_output(fd, vq);
+                               if (vq->handle_output)
+                                       vq->handle_output(fd, vq);
                                return;
                        }
                }
@@ -1068,7 +1068,8 @@ static void add_virtqueue(struct device *dev, unsigned int num_descs,
         * virtqueue. */
        vq->handle_output = handle_output;
 
-       /* Set the "Don't Notify Me" flag if we don't have a handler */
+       /* As an optimization, set the advisory "Don't Notify Me" flag if we
+        * don't have a handler */
        if (!handle_output)
                vq->vring.used->flags = VRING_USED_F_NO_NOTIFY;
 }