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SubjectRe: [PATCH] xhci: Ensure a command structure points to the correct trb on the command ring
Hi Xiao,

I think you did something odd when you tried to send me the latest
revision of your patch "xhci: correct the usage of
USB_CTRL_SET_TIMEOUT". You sent this patch instead. On the plus side,
it looks like git-send-email works.

Can you try again?

Sarah Sharp

On Fri, Oct 11, 2013 at 08:47:54AM +0800, xiao jin wrote:
> From: Mathias Nyman <mathias.nyman@linux.intel.com>
>
> If a command on the command ring needs to be cancelled before it is handled
> it can be turned to a no-op operation when the ring is stopped.
> We want to store the command ring enqueue pointer in the command structure
> when the command in enqueued for the cancellation case.
>
> Some commands used to store the command ring dequeue pointers instead of enqueue
> (these often worked because enqueue happends to equal dequeue quite often)
>
> Other commands correctly used the enqueue pointer but did not check if it pointed
> to a valid trb or a link trb, this caused for example stop endpoint command to timeout in
> xhci_stop_device() in about 2% of suspend/resume cases.
>
> This should also solve some weird behavior happening in command cancellation cases.
>
> This patch is based on a patch submitted by Sarah Sharp to linux-usb, but
> then forgotten:
> http://marc.info/?l=linux-usb&m=136269803207465&w=2
>
> This patch should be backported to kernels as old as 3.7, that contain
> the commit b92cc66c047ff7cf587b318fe377061a353c120f "xHCI: add aborting
> command ring function"
>
> Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com>
> Signed-off-by: Sarah Sharp <sarah.a.sharp@linux.intel.com>
> Cc: stable@vger.kernel.org
> ---
> drivers/usb/host/xhci-hub.c | 2 +-
> drivers/usb/host/xhci-ring.c | 10 ++++++++++
> drivers/usb/host/xhci.c | 25 +++++--------------------
> drivers/usb/host/xhci.h | 1 +
> 4 files changed, 17 insertions(+), 21 deletions(-)
>
> diff --git a/drivers/usb/host/xhci-hub.c b/drivers/usb/host/xhci-hub.c
> index fae697e..ccf0a06 100644
> --- a/drivers/usb/host/xhci-hub.c
> +++ b/drivers/usb/host/xhci-hub.c
> @@ -287,7 +287,7 @@ static int xhci_stop_device(struct xhci_hcd *xhci, int slot_id, int suspend)
> if (virt_dev->eps[i].ring && virt_dev->eps[i].ring->dequeue)
> xhci_queue_stop_endpoint(xhci, slot_id, i, suspend);
> }
> - cmd->command_trb = xhci->cmd_ring->enqueue;
> + cmd->command_trb = xhci_find_next_enqueue(xhci->cmd_ring);
> list_add_tail(&cmd->cmd_list, &virt_dev->cmd_list);
> xhci_queue_stop_endpoint(xhci, slot_id, 0, suspend);
> xhci_ring_cmd_db(xhci);
> diff --git a/drivers/usb/host/xhci-ring.c b/drivers/usb/host/xhci-ring.c
> index aaa2906..9ac9672 100644
> --- a/drivers/usb/host/xhci-ring.c
> +++ b/drivers/usb/host/xhci-ring.c
> @@ -123,6 +123,16 @@ static int enqueue_is_link_trb(struct xhci_ring *ring)
> return TRB_TYPE_LINK_LE32(link->control);
> }
>
> +union xhci_trb *xhci_find_next_enqueue(struct xhci_ring *ring)
> +{
> + /* Enqueue pointer can be left pointing to the link TRB,
> + * we must handle that
> + */
> + if (TRB_TYPE_LINK_LE32(ring->enqueue->link.control))
> + return ring->enq_seg->next->trbs;
> + return ring->enqueue;
> +}
> +
> /* Updates trb to point to the next TRB in the ring, and updates seg if the next
> * TRB is in a new segment. This does not skip over link TRBs, and it does not
> * effect the ring dequeue or enqueue pointers.
> diff --git a/drivers/usb/host/xhci.c b/drivers/usb/host/xhci.c
> index 49b6edb..1e36dbb 100644
> --- a/drivers/usb/host/xhci.c
> +++ b/drivers/usb/host/xhci.c
> @@ -2598,15 +2598,7 @@ static int xhci_configure_endpoint(struct xhci_hcd *xhci,
> if (command) {
> cmd_completion = command->completion;
> cmd_status = &command->status;
> - command->command_trb = xhci->cmd_ring->enqueue;
> -
> - /* Enqueue pointer can be left pointing to the link TRB,
> - * we must handle that
> - */
> - if (TRB_TYPE_LINK_LE32(command->command_trb->link.control))
> - command->command_trb =
> - xhci->cmd_ring->enq_seg->next->trbs;
> -
> + command->command_trb = xhci_find_next_enqueue(xhci->cmd_ring);
> list_add_tail(&command->cmd_list, &virt_dev->cmd_list);
> } else {
> cmd_completion = &virt_dev->cmd_completion;
> @@ -2614,7 +2606,7 @@ static int xhci_configure_endpoint(struct xhci_hcd *xhci,
> }
> init_completion(cmd_completion);
>
> - cmd_trb = xhci->cmd_ring->dequeue;
> + cmd_trb = xhci_find_next_enqueue(xhci->cmd_ring);
> if (!ctx_change)
> ret = xhci_queue_configure_endpoint(xhci, in_ctx->dma,
> udev->slot_id, must_succeed);
> @@ -3439,14 +3431,7 @@ int xhci_discover_or_reset_device(struct usb_hcd *hcd, struct usb_device *udev)
>
> /* Attempt to submit the Reset Device command to the command ring */
> spin_lock_irqsave(&xhci->lock, flags);
> - reset_device_cmd->command_trb = xhci->cmd_ring->enqueue;
> -
> - /* Enqueue pointer can be left pointing to the link TRB,
> - * we must handle that
> - */
> - if (TRB_TYPE_LINK_LE32(reset_device_cmd->command_trb->link.control))
> - reset_device_cmd->command_trb =
> - xhci->cmd_ring->enq_seg->next->trbs;
> + reset_device_cmd->command_trb = xhci_find_next_enqueue(xhci->cmd_ring);
>
> list_add_tail(&reset_device_cmd->cmd_list, &virt_dev->cmd_list);
> ret = xhci_queue_reset_device(xhci, slot_id);
> @@ -3650,7 +3635,7 @@ int xhci_alloc_dev(struct usb_hcd *hcd, struct usb_device *udev)
> union xhci_trb *cmd_trb;
>
> spin_lock_irqsave(&xhci->lock, flags);
> - cmd_trb = xhci->cmd_ring->dequeue;
> + cmd_trb = xhci_find_next_enqueue(xhci->cmd_ring);
> ret = xhci_queue_slot_control(xhci, TRB_ENABLE_SLOT, 0);
> if (ret) {
> spin_unlock_irqrestore(&xhci->lock, flags);
> @@ -3785,7 +3770,7 @@ int xhci_address_device(struct usb_hcd *hcd, struct usb_device *udev)
> slot_ctx->dev_info >> 27);
>
> spin_lock_irqsave(&xhci->lock, flags);
> - cmd_trb = xhci->cmd_ring->dequeue;
> + cmd_trb = xhci_find_next_enqueue(xhci->cmd_ring);
> ret = xhci_queue_address_device(xhci, virt_dev->in_ctx->dma,
> udev->slot_id);
> if (ret) {
> diff --git a/drivers/usb/host/xhci.h b/drivers/usb/host/xhci.h
> index 46aa148..f3e1020 100644
> --- a/drivers/usb/host/xhci.h
> +++ b/drivers/usb/host/xhci.h
> @@ -1840,6 +1840,7 @@ int xhci_cancel_cmd(struct xhci_hcd *xhci, struct xhci_command *command,
> union xhci_trb *cmd_trb);
> void xhci_ring_ep_doorbell(struct xhci_hcd *xhci, unsigned int slot_id,
> unsigned int ep_index, unsigned int stream_id);
> +union xhci_trb *xhci_find_next_enqueue(struct xhci_ring *ring);
>
> /* xHCI roothub code */
> void xhci_set_link_state(struct xhci_hcd *xhci, __le32 __iomem **port_array,
> --
> 1.7.1
>


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