diff options
author | Jason Wang <jasowang@redhat.com> | 2013-09-02 16:40:58 +0800 |
---|---|---|
committer | David S. Miller <davem@davemloft.net> | 2013-09-03 22:46:57 -0400 |
commit | c49e4e573be86acd36c747511ea5dc76be122206 (patch) | |
tree | 682e11f8da283fb6ddc3ab5bd8bbae3486726afd /drivers/vhost/vhost.c | |
parent | c92112aed3f0b14fdd2dbd9f192cce1af22c0e1c (diff) |
vhost: switch to use vhost_add_used_n()
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>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'drivers/vhost/vhost.c')
-rw-r--r-- | 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 448efe01f18a..9a9502a4aa50 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; } |