Re: [PATCH] xhci: Ensure a command structure points to the correct trb on the command ring

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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@xxxxxxxxxxxxxxx>
> 
> 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@xxxxxxxxxxxxxxx>
> Signed-off-by: Sarah Sharp <sarah.a.sharp@xxxxxxxxxxxxxxx>
> Cc: stable@xxxxxxxxxxxxxxx
> ---
>  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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