On Wed, Dec 18, 2013 at 11:24:47AM -0000, David Laight wrote:
> This saves a kzalloc() call on every transfer and some memory
> indirections.
>
> The only possible downside is for isochronous tranfers with 64 td
> when the allocate is 8+4096 bytes (on 64bit systems) so requires
> an additional page.
If you take this to embedded world there could be a bad side effect too.
The free memory isn't abundant and the fragmentation may make a bigger
kmalloc() to cost more than 2 smaller ones.
Br, David Cohen
>
> Signed-off-by: David Laight <david.laight@xxxxxxxxxx>
> ---
>
> v2: Added signed-off-by line
>
> drivers/usb/host/xhci-mem.c | 4 +---
> drivers/usb/host/xhci-ring.c | 22 ++++++++++------------
> drivers/usb/host/xhci.c | 24 ++++++------------------
> drivers/usb/host/xhci.h | 2 +-
> 4 files changed, 18 insertions(+), 34 deletions(-)
>
> diff --git a/drivers/usb/host/xhci-mem.c b/drivers/usb/host/xhci-mem.c
> index 79cdcc2..9b5d1c3 100644
> --- a/drivers/usb/host/xhci-mem.c
> +++ b/drivers/usb/host/xhci-mem.c
> @@ -1675,10 +1675,8 @@ struct xhci_command *xhci_alloc_command(struct xhci_hcd *xhci,
>
> void xhci_urb_free_priv(struct xhci_hcd *xhci, struct urb_priv *urb_priv)
> {
> - if (urb_priv) {
> - kfree(urb_priv->td[0]);
> + if (urb_priv)
> kfree(urb_priv);
> - }
> }
>
> void xhci_free_command(struct xhci_hcd *xhci,
> diff --git a/drivers/usb/host/xhci-ring.c b/drivers/usb/host/xhci-ring.c
> index e38abc2..d3f4a9a 100644
> --- a/drivers/usb/host/xhci-ring.c
> +++ b/drivers/usb/host/xhci-ring.c
> @@ -3007,7 +3007,7 @@ static int prepare_transfer(struct xhci_hcd *xhci,
> return ret;
>
> urb_priv = urb->hcpriv;
> - td = urb_priv->td[td_index];
> + td = &urb_priv->td[td_index];
>
> INIT_LIST_HEAD(&td->td_list);
> INIT_LIST_HEAD(&td->cancelled_td_list);
> @@ -3024,8 +3024,6 @@ static int prepare_transfer(struct xhci_hcd *xhci,
> td->start_seg = ep_ring->enq_seg;
> td->first_trb = ep_ring->enqueue;
>
> - urb_priv->td[td_index] = td;
> -
> return 0;
> }
>
> @@ -3216,7 +3214,7 @@ static int queue_bulk_sg_tx(struct xhci_hcd *xhci, gfp_t mem_flags,
> return trb_buff_len;
>
> urb_priv = urb->hcpriv;
> - td = urb_priv->td[0];
> + td = &urb_priv->td[0];
>
> /*
> * Don't give the first TRB to the hardware (by toggling the cycle bit)
> @@ -3387,7 +3385,7 @@ int xhci_queue_bulk_tx(struct xhci_hcd *xhci, gfp_t mem_flags,
> return ret;
>
> urb_priv = urb->hcpriv;
> - td = urb_priv->td[0];
> + td = &urb_priv->td[0];
>
> /*
> * Don't give the first TRB to the hardware (by toggling the cycle bit)
> @@ -3517,7 +3515,7 @@ int xhci_queue_ctrl_tx(struct xhci_hcd *xhci, gfp_t mem_flags,
> return ret;
>
> urb_priv = urb->hcpriv;
> - td = urb_priv->td[0];
> + td = &urb_priv->td[0];
>
> /*
> * Don't give the first TRB to the hardware (by toggling the cycle bit)
> @@ -3729,7 +3727,7 @@ static int xhci_queue_isoc_tx(struct xhci_hcd *xhci, gfp_t mem_flags,
> goto cleanup;
> }
>
> - td = urb_priv->td[i];
> + td = &urb_priv->td[i];
> for (j = 0; j < trbs_per_td; j++) {
> u32 remainder = 0;
> field = 0;
> @@ -3829,20 +3827,20 @@ cleanup:
> /* Clean up a partially enqueued isoc transfer. */
>
> for (i--; i >= 0; i--)
> - list_del_init(&urb_priv->td[i]->td_list);
> + list_del_init(&urb_priv->td[i].td_list);
>
> /* Use the first TD as a temporary variable to turn the TDs we've queued
> * into No-ops with a software-owned cycle bit. That way the hardware
> * won't accidentally start executing bogus TDs when we partially
> * overwrite them. td->first_trb and td->start_seg are already set.
> */
> - urb_priv->td[0]->last_trb = ep_ring->enqueue;
> + urb_priv->td[0].last_trb = ep_ring->enqueue;
> /* Every TRB except the first & last will have its cycle bit flipped. */
> - td_to_noop(xhci, ep_ring, urb_priv->td[0], true);
> + td_to_noop(xhci, ep_ring, &urb_priv->td[0], true);
>
> /* Reset the ring enqueue back to the first TRB and its cycle bit. */
> - ep_ring->enqueue = urb_priv->td[0]->first_trb;
> - ep_ring->enq_seg = urb_priv->td[0]->start_seg;
> + ep_ring->enqueue = urb_priv->td[0].first_trb;
> + ep_ring->enq_seg = urb_priv->td[0].start_seg;
> ep_ring->cycle_state = start_cycle;
> ep_ring->num_trbs_free = ep_ring->num_trbs_free_temp;
> usb_hcd_unlink_urb_from_ep(bus_to_hcd(urb->dev->bus), urb);
> diff --git a/drivers/usb/host/xhci.c b/drivers/usb/host/xhci.c
> index 6e0d886..0969f74 100644
> --- a/drivers/usb/host/xhci.c
> +++ b/drivers/usb/host/xhci.c
> @@ -1248,12 +1248,11 @@ static int xhci_check_maxpacket(struct xhci_hcd *xhci, unsigned int slot_id,
> int xhci_urb_enqueue(struct usb_hcd *hcd, struct urb *urb, gfp_t mem_flags)
> {
> struct xhci_hcd *xhci = hcd_to_xhci(hcd);
> - struct xhci_td *buffer;
> unsigned long flags;
> int ret = 0;
> unsigned int slot_id, ep_index;
> struct urb_priv *urb_priv;
> - int size, i;
> + int size;
>
> if (!urb || xhci_check_args(hcd, urb->dev, urb->ep,
> true, true, __func__) <= 0)
> @@ -1275,21 +1274,10 @@ int xhci_urb_enqueue(struct usb_hcd *hcd, struct urb *urb, gfp_t mem_flags)
> size = 1;
>
> urb_priv = kzalloc(sizeof(struct urb_priv) +
> - size * sizeof(struct xhci_td *), mem_flags);
> + size * sizeof(struct xhci_td), mem_flags);
> if (!urb_priv)
> return -ENOMEM;
>
> - buffer = kzalloc(size * sizeof(struct xhci_td), mem_flags);
> - if (!buffer) {
> - kfree(urb_priv);
> - return -ENOMEM;
> - }
> -
> - for (i = 0; i < size; i++) {
> - urb_priv->td[i] = buffer;
> - buffer++;
> - }
> -
> urb_priv->length = size;
> urb_priv->td_cnt = 0;
> urb->hcpriv = urb_priv;
> @@ -1470,7 +1458,7 @@ int xhci_urb_dequeue(struct usb_hcd *hcd, struct urb *urb, int status)
> "HW died, freeing TD.");
> urb_priv = urb->hcpriv;
> for (i = urb_priv->td_cnt; i < urb_priv->length; i++) {
> - td = urb_priv->td[i];
> + td = &urb_priv->td[i];
> if (!list_empty(&td->td_list))
> list_del_init(&td->td_list);
> if (!list_empty(&td->cancelled_td_list))
> @@ -1514,11 +1502,11 @@ int xhci_urb_dequeue(struct usb_hcd *hcd, struct urb *urb, int status)
> urb, urb->dev->devpath,
> urb->ep->desc.bEndpointAddress,
> (unsigned long long) xhci_trb_virt_to_dma(
> - urb_priv->td[i]->start_seg,
> - urb_priv->td[i]->first_trb));
> + urb_priv->td[i].start_seg,
> + urb_priv->td[i].first_trb));
>
> for (; i < urb_priv->length; i++) {
> - td = urb_priv->td[i];
> + td = &urb_priv->td[i];
> list_add_tail(&td->cancelled_td_list, &ep->cancelled_td_list);
> }
>
> diff --git a/drivers/usb/host/xhci.h b/drivers/usb/host/xhci.h
> index 72ad988..a7d8fdd 100644
> --- a/drivers/usb/host/xhci.h
> +++ b/drivers/usb/host/xhci.h
> @@ -1363,7 +1363,7 @@ struct xhci_scratchpad {
> struct urb_priv {
> int length;
> int td_cnt;
> - struct xhci_td *td[0];
> + struct xhci_td td[0];
> };
>
> /*
> --
> 1.8.1.2
>
>
>
> --
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