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

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On Fri, Oct 11, 2013 at 10:25:23AM -0700, Sarah Sharp wrote:
> 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?

Ah, nevermind, I saw the v2 patch you sent later.

Sarah

> 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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