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

From: Xiao Jin
Date: Fri Oct 11 2013 - 20:47:47 EST

Sarah,

As you said, I make a mistake and send wrong patch. I am sorry for it.

On Fri, 2013-10-11 at 10:28 -0700, Sarah Sharp wrote:
> 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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