From: Jason Wang <jasowang@redhat.com>
To: mst@redhat.com, kvm@vger.kernel.org,
virtualization@lists.linux-foundation.org,
netdev@vger.kernel.org, linux-kernel@vger.kernel.org
Cc: Jason Wang <jasowang@redhat.com>
Subject: [PATCH V3 3/6] vhost: switch to use vhost_add_used_n()
Date: Mon, 2 Sep 2013 16:40:58 +0800 [thread overview]
Message-ID: <1378111261-14826-4-git-send-email-jasowang@redhat.com> (raw)
In-Reply-To: <1378111261-14826-1-git-send-email-jasowang@redhat.com>
Let vhost_add_used() to use vhost_add_used_n() to reduce the code
duplication. To avoid the overhead brought by __copy_to_user(). We will use
put_user() when one used need to be added.
Signed-off-by: Jason Wang <jasowang@redhat.com>
---
drivers/vhost/vhost.c | 54 ++++++++++--------------------------------------
1 files changed, 12 insertions(+), 42 deletions(-)
diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c
index 448efe0..9a9502a 100644
--- a/drivers/vhost/vhost.c
+++ b/drivers/vhost/vhost.c
@@ -1332,48 +1332,9 @@ EXPORT_SYMBOL_GPL(vhost_discard_vq_desc);
* want to notify the guest, using eventfd. */
int vhost_add_used(struct vhost_virtqueue *vq, unsigned int head, int len)
{
- struct vring_used_elem __user *used;
+ struct vring_used_elem heads = { head, len };
- /* The virtqueue contains a ring of used buffers. Get a pointer to the
- * next entry in that used ring. */
- used = &vq->used->ring[vq->last_used_idx % vq->num];
- if (__put_user(head, &used->id)) {
- vq_err(vq, "Failed to write used id");
- return -EFAULT;
- }
- if (__put_user(len, &used->len)) {
- vq_err(vq, "Failed to write used len");
- return -EFAULT;
- }
- /* Make sure buffer is written before we update index. */
- smp_wmb();
- if (__put_user(vq->last_used_idx + 1, &vq->used->idx)) {
- vq_err(vq, "Failed to increment used idx");
- return -EFAULT;
- }
- if (unlikely(vq->log_used)) {
- /* Make sure data is seen before log. */
- smp_wmb();
- /* Log used ring entry write. */
- log_write(vq->log_base,
- vq->log_addr +
- ((void __user *)used - (void __user *)vq->used),
- sizeof *used);
- /* Log used index update. */
- log_write(vq->log_base,
- vq->log_addr + offsetof(struct vring_used, idx),
- sizeof vq->used->idx);
- if (vq->log_ctx)
- eventfd_signal(vq->log_ctx, 1);
- }
- vq->last_used_idx++;
- /* If the driver never bothers to signal in a very long while,
- * used index might wrap around. If that happens, invalidate
- * signalled_used index we stored. TODO: make sure driver
- * signals at least once in 2^16 and remove this. */
- if (unlikely(vq->last_used_idx == vq->signalled_used))
- vq->signalled_used_valid = false;
- return 0;
+ return vhost_add_used_n(vq, &heads, 1);
}
EXPORT_SYMBOL_GPL(vhost_add_used);
@@ -1387,7 +1348,16 @@ static int __vhost_add_used_n(struct vhost_virtqueue *vq,
start = vq->last_used_idx % vq->num;
used = vq->used->ring + start;
- if (__copy_to_user(used, heads, count * sizeof *used)) {
+ if (count == 1) {
+ if (__put_user(heads[0].id, &used->id)) {
+ vq_err(vq, "Failed to write used id");
+ return -EFAULT;
+ }
+ if (__put_user(heads[0].len, &used->len)) {
+ vq_err(vq, "Failed to write used len");
+ return -EFAULT;
+ }
+ } else if (__copy_to_user(used, heads, count * sizeof *used)) {
vq_err(vq, "Failed to write used");
return -EFAULT;
}
--
1.7.1
next prev parent reply other threads:[~2013-09-02 8:52 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-09-02 8:40 [PATCH V3 0/6] vhost code cleanup and minor enhancement Jason Wang
2013-09-02 8:40 ` [PATCH V3 1/6] vhost_net: make vhost_zerocopy_signal_used() return void Jason Wang
2013-09-02 8:40 ` [PATCH V3 2/6] vhost_net: use vhost_add_used_and_signal_n() in vhost_zerocopy_signal_used() Jason Wang
2013-09-02 8:40 ` Jason Wang [this message]
2013-09-02 8:40 ` [PATCH V3 4/6] vhost_net: determine whether or not to use zerocopy at one time Jason Wang
2013-09-04 11:59 ` Michael S. Tsirkin
2013-09-05 2:54 ` Jason Wang
2013-09-23 7:16 ` Michael S. Tsirkin
2013-09-26 4:30 ` Jason Wang
2013-09-29 9:36 ` Jason Wang
2013-09-02 8:41 ` [PATCH V3 5/6] vhost_net: poll vhost queue after marking DMA is done Jason Wang
2013-09-02 8:41 ` [PATCH V3 6/6] vhost_net: correctly limit the max pending buffers Jason Wang
2013-09-04 2:47 ` [PATCH V3 0/6] vhost code cleanup and minor enhancement David Miller
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