search for: next_avail_idx

On Fri, Aug 09, 2019 at 12:18:47PM +0530, Pankaj Gupta wrote: > This patch decrements 'next_avail_idx' count when detaching a buffer > from vq for packed ring code. Split ring code already does this in > virtqueue_detach_unused_buf_split function. This updates the > 'next_avail_idx' to the previous correct index after an unused buffer > is detatched from the vq. > > S...

On 2019/8/9 ??2:48, Pankaj Gupta wrote: > This patch decrements 'next_avail_idx' count when detaching a buffer > from vq for packed ring code. Split ring code already does this in > virtqueue_detach_unused_buf_split function. This updates the > 'next_avail_idx' to the previous correct index after an unused buffer > is detatched from the vq. > > Si...

...16 new, old, off_wrap, flags, wrap_counter, event_idx; > bool needs_kick; > u32 snapshot; > > @@ -1015,9 +1015,19 @@ static bool virtqueue_kick_prepare_packed(struct virtqueue *_vq) > * suppressions. */ > virtio_mb(vq->weak_barriers); > > + old = vq->next_avail_idx - vq->num_added; > + new = vq->next_avail_idx; > + vq->num_added = 0; > + > snapshot = *(u32 *)vq->vring_packed.device; > + off_wrap = virtio16_to_cpu(_vq->vdev, (__virtio16)(snapshot & 0xffff)); > flags = virtio16_to_cpu(_vq->vdev, (__virtio16)(snapsho...

...16 new, old, off_wrap, flags, wrap_counter, event_idx; > bool needs_kick; > u32 snapshot; > > @@ -1015,9 +1015,19 @@ static bool virtqueue_kick_prepare_packed(struct virtqueue *_vq) > * suppressions. */ > virtio_mb(vq->weak_barriers); > > + old = vq->next_avail_idx - vq->num_added; > + new = vq->next_avail_idx; > + vq->num_added = 0; > + > snapshot = *(u32 *)vq->vring_packed.device; > + off_wrap = virtio16_to_cpu(_vq->vdev, (__virtio16)(snapshot & 0xffff)); > flags = virtio16_to_cpu(_vq->vdev, (__virtio16)(snapsho...

This patch series fixes the issue with unplug/replug of a port in virtio console driver which fails with an error "Error allocating inbufs\n". Patch 1 makes use of 'virtqueue_detach_unused_buf' function to detach the unused buffers during port hotunplug time. Patch 2 updates the next avail index for packed ring code. Tested the packed ring code with the qemu virtio 1.1 device

...t; > > > > u32 snapshot; > > > > > @@ -995,7 +995,12 @@ static bool virtqueue_kick_prepare_packed(struct virtqueue *_vq) > > > > > * suppressions. */ > > > > > virtio_mb(vq->weak_barriers); > > > > > + old = vq->next_avail_idx - vq->num_added; > > > > > + new = vq->next_avail_idx; > > > > > + vq->num_added = 0; > > > > > + > > > > > snapshot = *(u32 *)vq->vring_packed.device; > > > > > + off_wrap = virtio16_to_cpu(_vq->vdev, snap...

...t; > > > > u32 snapshot; > > > > > @@ -995,7 +995,12 @@ static bool virtqueue_kick_prepare_packed(struct virtqueue *_vq) > > > > > * suppressions. */ > > > > > virtio_mb(vq->weak_barriers); > > > > > + old = vq->next_avail_idx - vq->num_added; > > > > > + new = vq->next_avail_idx; > > > > > + vq->num_added = 0; > > > > > + > > > > > snapshot = *(u32 *)vq->vring_packed.device; > > > > > + off_wrap = virtio16_to_cpu(_vq->vdev, snap...

...wrap, flags; > > > bool needs_kick; > > > u32 snapshot; > > > @@ -995,7 +995,12 @@ static bool virtqueue_kick_prepare_packed(struct virtqueue *_vq) > > > * suppressions. */ > > > virtio_mb(vq->weak_barriers); > > > + old = vq->next_avail_idx - vq->num_added; > > > + new = vq->next_avail_idx; > > > + vq->num_added = 0; > > > + > > > snapshot = *(u32 *)vq->vring_packed.device; > > > + off_wrap = virtio16_to_cpu(_vq->vdev, snapshot & 0xffff); > > > flags = cpu_...

...wrap, flags; > > > bool needs_kick; > > > u32 snapshot; > > > @@ -995,7 +995,12 @@ static bool virtqueue_kick_prepare_packed(struct virtqueue *_vq) > > > * suppressions. */ > > > virtio_mb(vq->weak_barriers); > > > + old = vq->next_avail_idx - vq->num_added; > > > + new = vq->next_avail_idx; > > > + vq->num_added = 0; > > > + > > > snapshot = *(u32 *)vq->vring_packed.device; > > > + off_wrap = virtio16_to_cpu(_vq->vdev, snapshot & 0xffff); > > > flags = cpu_...

..._virtqueue *vq = to_vvq(_vq); - u16 flags; + u16 new, old, off_wrap, flags, wrap_counter, event_idx; bool needs_kick; u32 snapshot; @@ -1015,9 +1015,19 @@ static bool virtqueue_kick_prepare_packed(struct virtqueue *_vq) * suppressions. */ virtio_mb(vq->weak_barriers); + old = vq->next_avail_idx - vq->num_added; + new = vq->next_avail_idx; + vq->num_added = 0; + snapshot = *(u32 *)vq->vring_packed.device; + off_wrap = virtio16_to_cpu(_vq->vdev, (__virtio16)(snapshot & 0xffff)); flags = virtio16_to_cpu(_vq->vdev, (__virtio16)(snapshot >> 16)) & 0x3; + w...

...> > > > > > > @@ -995,7 +995,12 @@ static bool virtqueue_kick_prepare_packed(struct virtqueue *_vq) > > > > > > > * suppressions. */ > > > > > > > virtio_mb(vq->weak_barriers); > > > > > > > + old = vq->next_avail_idx - vq->num_added; > > > > > > > + new = vq->next_avail_idx; > > > > > > > + vq->num_added = 0; > > > > > > > + > > > > > > > snapshot = *(u32 *)vq->vring_packed.device; > > > > > > &g...

...> > > > > > > @@ -995,7 +995,12 @@ static bool virtqueue_kick_prepare_packed(struct virtqueue *_vq) > > > > > > > * suppressions. */ > > > > > > > virtio_mb(vq->weak_barriers); > > > > > > > + old = vq->next_avail_idx - vq->num_added; > > > > > > > + new = vq->next_avail_idx; > > > > > > > + vq->num_added = 0; > > > > > > > + > > > > > > > snapshot = *(u32 *)vq->vring_packed.device; > > > > > > &g...

...> - u16 flags; > + u16 new, old, off_wrap, flags; > bool needs_kick; > u32 snapshot; > > @@ -995,7 +995,12 @@ static bool virtqueue_kick_prepare_packed(struct virtqueue *_vq) > * suppressions. */ > virtio_mb(vq->weak_barriers); > > + old = vq->next_avail_idx - vq->num_added; > + new = vq->next_avail_idx; > + vq->num_added = 0; > + > snapshot = *(u32 *)vq->vring_packed.device; > + off_wrap = virtio16_to_cpu(_vq->vdev, snapshot & 0xffff); > flags = cpu_to_virtio16(_vq->vdev, snapshot >> 16) & 0x3; &...

..._USED_EVENT_IDX feature, we need to > > + * either clear the flags bit or point the event index at the next > > + * entry. Always update the event index to keep code simple. */ > > + > > + wrap_counter = vq->wrap_counter; > > + if (vq->last_used_idx > vq->next_avail_idx) > > Should this be ">=" consider rx refill may try to completely fill the ring? It seems that there are two cases that last_used_idx equals to next_avail_idx. The first one is that the ring is empty. And the second one is that the ring is full. Although in the first case, most...

...e're using some buffers from the free list. */ > + vq->vq.num_free -= descs_used; > + > + /* Update free pointer */ > + if (indirect) { > + n = head + 1; > + if (n >= vq->vring_packed.num) { > + n = 0; > + vq->wrap_counter ^= 1; > + } > + vq->next_avail_idx = n; > + } else > + vq->next_avail_idx = i; During testing zerocopy (out of order completion), I found driver may submit two identical buffer id to vhost. So the above code may not work well. Consider the case that driver adds 3 buffer and virtqueue size is 8. a) id = 0,count = 2,nex...

...e're using some buffers from the free list. */ > + vq->vq.num_free -= descs_used; > + > + /* Update free pointer */ > + if (indirect) { > + n = head + 1; > + if (n >= vq->vring_packed.num) { > + n = 0; > + vq->wrap_counter ^= 1; > + } > + vq->next_avail_idx = n; > + } else > + vq->next_avail_idx = i; During testing zerocopy (out of order completion), I found driver may submit two identical buffer id to vhost. So the above code may not work well. Consider the case that driver adds 3 buffer and virtqueue size is 8. a) id = 0,count = 2,nex...

...> > > > @@ -995,7 +995,12 @@ static bool virtqueue_kick_prepare_packed(struct virtqueue *_vq) > > > > > > > > * suppressions. */ > > > > > > > > virtio_mb(vq->weak_barriers); > > > > > > > > + old = vq->next_avail_idx - vq->num_added; > > > > > > > > + new = vq->next_avail_idx; > > > > > > > > + vq->num_added = 0; > > > > > > > > + > > > > > > > > snapshot = *(u32 *)vq->vring_packed.device; > > &g...

...t; bool needs_kick; > > > > u32 snapshot; > > > > @@ -995,7 +995,12 @@ static bool virtqueue_kick_prepare_packed(struct virtqueue *_vq) > > > > * suppressions. */ > > > > virtio_mb(vq->weak_barriers); > > > > + old = vq->next_avail_idx - vq->num_added; > > > > + new = vq->next_avail_idx; > > > > + vq->num_added = 0; > > > > + > > > > snapshot = *(u32 *)vq->vring_packed.device; > > > > + off_wrap = virtio16_to_cpu(_vq->vdev, snapshot & 0xffff); >...

This patch decrements 'next_avail_idx' count when detaching a buffer from vq for packed ring code. Split ring code already does this in virtqueue_detach_unused_buf_split function. This updates the 'next_avail_idx' to the previous correct index after an unused buffer is detatched from the vq. Signed-off-by: Pankaj Gupta &lt...

...t; u32 snapshot; > > > > > > @@ -995,7 +995,12 @@ static bool virtqueue_kick_prepare_packed(struct virtqueue *_vq) > > > > > > * suppressions. */ > > > > > > virtio_mb(vq->weak_barriers); > > > > > > + old = vq->next_avail_idx - vq->num_added; > > > > > > + new = vq->next_avail_idx; > > > > > > + vq->num_added = 0; > > > > > > + > > > > > > snapshot = *(u32 *)vq->vring_packed.device; > > > > > > + off_wrap = virtio16_...