From 0174b0c30a9de25dcb0d3049defcfad0c2947a36 Mon Sep 17 00:00:00 2001
From: "Michael S. Tsirkin" <mst@redhat.com>
Date: Mon, 10 Jan 2011 10:03:20 +0200
Subject: [PATCH] vhost: fix signed/unsigned comparison
To detect that a sequence number is done, we are doing math on unsigned
integers so the result is unsigned too. Not what was intended for the <=
comparison. The result is user stuck forever in flush call.
Convert to int to fix this.
Further, get rid of ({}) to make code clearer.
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
---
drivers/vhost/vhost.c | 18 +++++++++++-------
1 file changed, 11 insertions(+), 7 deletions(-)
diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c
index 38244f59cdd91..ade0568c07a4e 100644
--- a/drivers/vhost/vhost.c
+++ b/drivers/vhost/vhost.c
@@ -97,22 +97,26 @@ void vhost_poll_stop(struct vhost_poll *poll)
remove_wait_queue(poll->wqh, &poll->wait);
}
+static bool vhost_work_seq_done(struct vhost_dev *dev, struct vhost_work *work,
+ unsigned seq)
+{
+ int left;
+ spin_lock_irq(&dev->work_lock);
+ left = seq - work->done_seq;
+ spin_unlock_irq(&dev->work_lock);
+ return left <= 0;
+}
+
static void vhost_work_flush(struct vhost_dev *dev, struct vhost_work *work)
{
unsigned seq;
- int left;
int flushing;
spin_lock_irq(&dev->work_lock);
seq = work->queue_seq;
work->flushing++;
spin_unlock_irq(&dev->work_lock);
- wait_event(work->done, ({
- spin_lock_irq(&dev->work_lock);
- left = seq - work->done_seq <= 0;
- spin_unlock_irq(&dev->work_lock);
- left;
- }));
+ wait_event(work->done, vhost_work_seq_done(dev, work, seq));
spin_lock_irq(&dev->work_lock);
flushing = --work->flushing;
spin_unlock_irq(&dev->work_lock);
--
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