From: "Michael S. Tsirkin" <mst@redhat.com>
To: "Michael S. Tsirkin" <mst@redhat.com>,
kvm@vger.kernel.org, virtualization@lists.linux-foundation.org,
netdev@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: [PATCH] vhost: copy_from_user -> __copy_from_user
Date: Sun, 6 Mar 2011 13:33:49 +0200 [thread overview]
Message-ID: <20110306113349.GA24333@redhat.com> (raw)
copy_from_user is pretty high on perf top profile,
replacing it with __copy_from_user helps.
It's also safe because we do access_ok checks during setup.
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
---
drivers/vhost/vhost.c | 2 +-
1 files changed, 1 insertions(+), 1 deletions(-)
diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c
index ade0568..01701b8 100644
--- a/drivers/vhost/vhost.c
+++ b/drivers/vhost/vhost.c
@@ -1153,7 +1153,7 @@ int vhost_get_vq_desc(struct vhost_dev *dev, struct vhost_virtqueue *vq,
i, vq->num, head);
return -EINVAL;
}
- ret = copy_from_user(&desc, vq->desc + i, sizeof desc);
+ ret = __copy_from_user(&desc, vq->desc + i, sizeof desc);
if (unlikely(ret)) {
vq_err(vq, "Failed to get descriptor: idx %d addr %p\n",
i, vq->desc + i);
--
1.7.3.2.91.g446ac
next reply other threads:[~2011-03-06 11:34 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-03-06 11:33 Michael S. Tsirkin [this message]
2011-03-07 2:03 ` [PATCH] vhost: copy_from_user -> __copy_from_user David Miller
2011-03-07 6:30 ` Michael S. Tsirkin
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