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vhost: avoid backend flush on vring ops 

vring changes already do a flush internally where appropriate, so we do
not need a second flush.

It's currently not very expensive but a follow-up patch makes flush more
heavy-weight, so remove the extra flush here to avoid regressing
performance if call or kick fds are changed on data path.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
This commit is contained in:
Michael S. Tsirkin 2012-12-06 14:03:34 +02:00
parent 4a7d6455b0
commit 935cdee7ee
4 changed files with 14 additions and 8 deletions
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7
drivers/vhost/net.c
View File

@ -942,8 +942,11 @@ static long vhost_net_ioctl(struct file *f, unsigned int ioctl,
return vhost_net_reset_owner(n);
default:
mutex_lock(&n->dev.mutex);
r = vhost_dev_ioctl(&n->dev, ioctl, arg);
vhost_net_flush(n);
r = vhost_dev_ioctl(&n->dev, ioctl, argp);
if (r == -ENOIOCTLCMD)
r = vhost_vring_ioctl(&n->dev, ioctl, argp);
else
vhost_net_flush(n);
mutex_unlock(&n->dev.mutex);
return r;
}

5
drivers/vhost/tcm_vhost.c
View File

@ -970,7 +970,10 @@ static long vhost_scsi_ioctl(struct file *f, unsigned int ioctl,
return vhost_scsi_set_features(vs, features);
default:
mutex_lock(&vs->dev.mutex);
r = vhost_dev_ioctl(&vs->dev, ioctl, arg);
r = vhost_dev_ioctl(&vs->dev, ioctl, argp);
/* TODO: flush backend after dev ioctl. */
if (r == -ENOIOCTLCMD)
r = vhost_vring_ioctl(&vs->dev, ioctl, argp);
mutex_unlock(&vs->dev.mutex);
return r;
}

7
drivers/vhost/vhost.c
View File

@ -607,7 +607,7 @@ static long vhost_set_memory(struct vhost_dev *d, struct vhost_memory __user *m)
return 0;
}
static long vhost_set_vring(struct vhost_dev *d, int ioctl, void __user *argp)
long vhost_vring_ioctl(struct vhost_dev *d, int ioctl, void __user *argp)
{
struct file *eventfp, *filep = NULL;
bool pollstart = false, pollstop = false;
@ -802,9 +802,8 @@ static long vhost_set_vring(struct vhost_dev *d, int ioctl, void __user *argp)
}
/* Caller must have device mutex */
long vhost_dev_ioctl(struct vhost_dev *d, unsigned int ioctl, unsigned long arg)
long vhost_dev_ioctl(struct vhost_dev *d, unsigned int ioctl, void __user *argp)
{
void __user *argp = (void __user *)arg;
struct file *eventfp, *filep = NULL;
struct eventfd_ctx *ctx = NULL;
u64 p;
@ -875,7 +874,7 @@ long vhost_dev_ioctl(struct vhost_dev *d, unsigned int ioctl, unsigned long arg)
fput(filep);
break;
default:
r = vhost_set_vring(d, ioctl, argp);
r = -ENOIOCTLCMD;
break;
}
done:

3
drivers/vhost/vhost.h
View File

@ -164,7 +164,8 @@ long vhost_dev_check_owner(struct vhost_dev *);
long vhost_dev_reset_owner(struct vhost_dev *);
void vhost_dev_cleanup(struct vhost_dev *, bool locked);
void vhost_dev_stop(struct vhost_dev *);
long vhost_dev_ioctl(struct vhost_dev *, unsigned int ioctl, unsigned long arg);
long vhost_dev_ioctl(struct vhost_dev *, unsigned int ioctl, void __user *argp);
long vhost_vring_ioctl(struct vhost_dev *d, int ioctl, void __user *argp);
int vhost_vq_access_ok(struct vhost_virtqueue *vq);
int vhost_log_access_ok(struct vhost_dev *);