linux/drivers/usb/host, branch v3.1

USB: xHCI: prevent infinite loop when processing MSE event

2011-09-20T00:15:47Z

When a xHC host is unable to handle isochronous transfer in the interval, it reports a Missed Service Error event and skips some tds. Currently xhci driver handles MSE event in the following ways: 1. When encounter a MSE event, set ep->skip flag, update event ring dequeue pointer and return. 2. When encounter the next event on this ep, the driver will run the do-while loop, fetch td from ep's td_list to find the td corresponding to this event. All tds missed are marked as short transfer(-EXDEV). The do-while loop will end in two ways: 1. If the td pointed by the event trb is found; 2. If the ep ring's td_list is empty. However, if a buggy HW reports some unpredicted event (for example, an overrun event following a MSE event while the ep ring is actually not empty), the driver will never find the td, and it will loop until the td_list is empty. Unfortunately, the spinlock is dropped when give back a urb in the do-while loop. During the spinlock released period, the class driver may still submit urbs and add tds to the td_list. This may cause disaster, since the td_list will never be empty and the loop never ends, and the system hangs. To fix this, count the number of TDs on the ep ring before skipping TDs, and quit the loop when skipped that number of tds. This guarantees the do-while loop will end after certain number of cycles, and driver will not be trapped in an infinite loop. Signed-off-by: Andiry Xu Signed-off-by: Sarah Sharp Signed-off-by: Greg Kroah-Hartman Signed-off-by: Linus Torvalds

USB: xhci: Set change bit when warm reset change is set.

2011-09-20T00:15:46Z

Sometimes, when a USB 3.0 device is disconnected, the Intel Panther Point xHCI host controller will report a link state change with the state set to "SS.Inactive". This causes the xHCI host controller to issue a warm port reset, which doesn't finish before the USB core times out while waiting for it to complete. When the warm port reset does complete, and the xHC gives back a port status change event, the xHCI driver kicks khubd. However, it fails to set the bit indicating there is a change event for that port because the logic in xhci-hub.c doesn't check for the warm port reset bit. After that, the warm port status change bit is never cleared by the USB core, and the xHC stops reporting port status change bits. (The xHCI spec says it shouldn't report more port events until all change bits are cleared.) This means any port changes when a new device is connected will never be reported, and the port will seem "dead" until the xHCI driver is unloaded and reloaded, or the computer is rebooted. Fix this by making the xHCI driver set the port change bit when a warm port reset change bit is set. A better solution would be to make the USB core handle warm port reset in differently, merging the current code with the standard port reset code that does an incremental backoff on the timeout, and tries to complete the port reset two more times before giving up. That more complicated fix will be merged next window, and this fix will be backported to stable. This should be backported to kernels as old as 3.0, since that was the first kernel with commit a11496ebf375 ("xHCI: warm reset support"). Signed-off-by: Sarah Sharp Cc: stable@kernel.org Signed-off-by: Greg Kroah-Hartman Signed-off-by: Linus Torvalds

usb: s5p-ehci: fix a NULL pointer deference

2011-08-22T20:38:52Z

This patch fixes a NULL pointer deference. A NULL pointer dereference happens since s5p_ehci->hcd field is not initialized yet in probe function. [jg1.han@samsung.com: edit commit message] Signed-off-by: Yulgon Kim Signed-off-by: Jingoo Han Cc: stable Signed-off-by: Greg Kroah-Hartman

USB: EHCI: Do not rely on PORT_SUSPEND to stop USB resuming in ehci_bus_resume().

2011-08-22T20:38:52Z

From EHCI Spec p.28 HC should clear PORT_SUSPEND when SW clears PORT_RESUME. In Intel Oaktrail platform, MPH (Multi-Port Host Controller) core clears PORT_SUSPEND directly when SW sets PORT_RESUME bit. If we rely on PORT_SUSPEND bit to stop USB resume, we will miss the action of clearing PORT_RESUME. This will cause unexpected long resume signal on USB bus. Signed-off-by: Wang Zhi Signed-off-by: Alan Stern Cc: stable Signed-off-by: Greg Kroah-Hartman

xhci: Handle zero-length isochronous packets.

2011-08-16T23:46:57Z

For a long time, the xHCI driver has had this note: /* FIXME: Ignoring zero-length packets, can those happen? */ It turns out that, yes, there are drivers that need to queue zero-length transfers for isochronous OUT transfers. Without this patch, users will see kernel hang messages when a driver attempts to enqueue an isochronous URB with a zero length transfer (because count_isoc_trbs_needed will return zero for that TD, xhci_td->last_trb will never be set, and updating the dequeue pointer will cause an infinite loop). Matěj ran into this issue when using an NI Audio4DJ USB soundcard with the snd-usb-caiaq driver. See https://bugzilla.kernel.org/show_bug.cgi?id=40702 Fix count_isoc_trbs_needed() to return 1 for zero-length transfers (thanks Alan on the math help). Update the various TRB field calculations to deal with zero-length transfers. We're still transferring one packet with a zero-length data payload, so the total_packet_count should be 1. The Transfer Burst Count (TBC) and Transfer Last Burst Packet Count (TLBPC) fields should be set to zero. This patch should be backported to kernels as old as 2.6.36. Signed-off-by: Sarah Sharp Tested-by: Matěj Laitl Cc: Daniel Mack Cc: Alan Stern Cc: stable@kernel.org

xhci: Remove TDs from TD lists when URBs are canceled.

2011-08-09T21:49:25Z

When a driver tries to cancel an URB, and the host controller is dying, xhci_urb_dequeue will giveback the URB without removing the xhci_tds that comprise that URB from the td_list or the cancelled_td_list. This can cause a race condition between the driver calling URB dequeue and the stop endpoint command watchdog timer. If the timer fires on a dying host, and a driver attempts to resubmit while the watchdog timer has dropped the xhci->lock to giveback a cancelled URB, URBs may be given back by the xhci_urb_dequeue() function. At that point, the URB's priv pointer will be freed and set to NULL, but the TDs will remain on the td_list. This will cause an oops in xhci_giveback_urb_in_irq() when the watchdog timer attempts to loop through the endpoints' td_lists, giving back killed URBs. Make sure that xhci_urb_dequeue() removes TDs from the TD lists and canceled TD lists before it gives back the URB. This patch should be backported to kernels as old as 2.6.36. Signed-off-by: Sarah Sharp Cc: Andiry Xu Cc: stable@kernel.org

xhci: Fix failed enqueue in the middle of isoch TD.

2011-08-09T21:49:05Z

When an isochronous transfer is enqueued, xhci_queue_isoc_tx_prepare() will ensure that there is enough room on the transfer rings for all of the isochronous TDs for that URB. However, when xhci_queue_isoc_tx() is enqueueing individual isoc TDs, the prepare_transfer() function can fail if the endpoint state has changed to disabled, error, or some other unknown state. With the current code, if Nth TD (not the first TD) fails, the ring is left in a sorry state. The partially enqueued TDs are left on the ring, and the first TRB of the TD is not given back to the hardware. The enqueue pointer is left on the TRB after the last successfully enqueued TD. This means the ring is basically useless. Any new transfers will be enqueued after the failed TDs, which the hardware will never read because the cycle bit indicates it does not own them. The ring will fill up with untransferred TDs, and the endpoint will be basically unusable. The untransferred TDs will also remain on the TD list. Since the td_list is a FIFO, this basically means the ring handler will be waiting on TDs that will never be completed (or worse, dereference memory that doesn't exist any more). Change the code to clean up the isochronous ring after a failed transfer. If the first TD failed, simply return and allow the xhci_urb_enqueue function to free the urb_priv. If the Nth TD failed, first remove the TDs from the td_list. Then convert the TRBs that were enqueued into No-op TRBs. Make sure to flip the cycle bit on all enqueued TRBs (including any link TRBs in the middle or between TDs), but leave the cycle bit of the first TRB (which will show software-owned) intact. Then move the ring enqueue pointer back to the first TRB and make sure to change the xhci_ring's cycle state to what is appropriate for that ring segment. This ensures that the No-op TRBs will be overwritten by subsequent TDs, and the hardware will not start executing random TRBs because the cycle bit was left as hardware-owned. This bug is unlikely to be hit, but it was something I noticed while tracking down the watchdog timer issue. I verified that the fix works by injecting some errors on the 250th isochronous URB queued, although I could not verify that the ring is in the correct state because uvcvideo refused to talk to the device after the first usb_submit_urb() failed. Ring debugging shows that the ring looks correct, however. This patch should be backported to kernels as old as 2.6.36. Signed-off-by: Sarah Sharp Cc: Andiry Xu Cc: stable@kernel.org

xhci: Fix memory leak during failed enqueue.

2011-08-09T21:48:45Z

When the isochronous transfer support was introduced, and the xHCI driver switched to using urb->hcpriv to store an "urb_priv" pointer, a couple of memory leaks were introduced into the URB enqueue function in its error handling paths. xhci_urb_enqueue allocates urb_priv, but it doesn't free it if changing the control endpoint's max packet size fails or the bulk endpoint is in the middle of allocating or deallocating streams. xhci_urb_enqueue also doesn't free urb_priv if any of the four endpoint types' enqueue functions fail. Instead, it expects those functions to free urb_priv if an error occurs. However, the bulk, control, and interrupt enqueue functions do not free urb_priv if the endpoint ring is NULL. It will, however, get freed if prepare_transfer() fails in those enqueue functions. Several of the error paths in the isochronous endpoint enqueue function also fail to free it. xhci_queue_isoc_tx_prepare() doesn't free urb_priv if prepare_ring() indicates there is not enough room for all the isochronous TDs in this URB. If individual isochronous TDs fail to be queued (perhaps due to an endpoint state change), urb_priv is also leaked. This argues that the freeing of urb_priv should be done in the function that allocated it, xhci_urb_enqueue. This patch looks rather ugly, but refactoring the code will have to wait because this patch needs to be backported to stable kernels. This patch should be backported to kernels as old as 2.6.36. Signed-off-by: Sarah Sharp Cc: Andiry Xu Cc: stable@kernel.org

xHCI: report USB2 port in resuming as suspend

2011-08-09T21:44:50Z

When a USB2 port initiate a remote wakeup, software shall ensure that resume is signaled for at least 20ms, and then write '0' to the PLS field. According to this, xhci driver do the following things: 1. When receive a remote wakeup event in irq_handler, set the resume_done value as jiffies + 20ms, and modify rh_timer to poll root hub status at that time; 2. When receive a GetPortStatus request, if the jiffies is after the resume_done value, clear the resume signal and resume_done. However, if usb_port_resume() is called before the rh_timer triggered, it will indicate the port as Suspend Cleared and skip the clear resume signal part. The device will fail the usb_get_status request in finish_port_resume(), and usbcore will try a reset-resume instead. Device will work OK after reset-resume, but resume_done value is not cleared in this case, and xhci_bus_suspend() will fail because when it finds a non-zero resume_done value, it will regard the port as resuming and return -EBUSY. This causes issue on some platforms that the system fail to suspend after remote wakeup from suspend by USB2 devices connected to xHCI port. To fix this issue, report the port status as suspend if the resume is signaling less that 20ms, and usb_port_resume() will wait 25ms and check port status again, so xHCI driver can clear the resume signaling and resume_done value. This should be backported to kernels as old as 2.6.37. Signed-off-by: Andiry Xu Signed-off-by: Sarah Sharp Cc: stable@kernel.org

xHCI: fix port U3 status check condition

2011-08-09T21:43:22Z

Fix the port U3 status check when Clear PORT_SUSPEND Feature. The port status should be masked with PORT_PLS_MASK to check if it's in U3 state. This should be backported to kernels as old as 2.6.37. Signed-off-by: Andiry Xu Signed-off-by: Sarah Sharp Cc: stable@kernel.org