Subject: vhost: fix warnings on 32 bit systems Date: Sun, 22 Nov 2009 12:28:01 +0200 From: Alan Cox Fix compiler warning about discarding top 32 bit of data on 32 bit systems, and document that dicarded bits must be 0. Signed-off-by: Alan Cox Signed-off-by: Michael S. Tsirkin (tweaked) Signed-off-by: Rusty Russell --- drivers/vhost/vhost.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c index 97233d5..e7b4dea 100644 --- a/drivers/vhost/vhost.c +++ b/drivers/vhost/vhost.c @@ -322,6 +322,8 @@ static long vhost_set_vring(struct vhost_dev *d, int ioctl, void __user *argp) r = -EOPNOTSUPP; break; } + /* For 32bit, verify that the top 32bits of the user + data are set to zero. */ if ((u64)(unsigned long)a.desc_user_addr != a.desc_user_addr || (u64)(unsigned long)a.used_user_addr != a.used_user_addr || (u64)(unsigned long)a.avail_user_addr != a.avail_user_addr) { @@ -334,7 +336,8 @@ static long vhost_set_vring(struct vhost_dev *d, int ioctl, void __user *argp) r = -EINVAL; break; } - r = init_used(vq, (struct vring_used __user *)a.used_user_addr); + r = init_used(vq, (struct vring_used __user *)(unsigned long) + a.used_user_addr); if (r) break; vq->log_used = !!(a.flags & (0x1 << VHOST_VRING_F_LOG));