xHCI: add aborting command ring function

Software have to abort command ring and cancel command
when a command is failed or hang. Otherwise, the command
ring will hang up and can't handle the others. An example
of a command that may hang is the Address Device Command,
because waiting for a SET_ADDRESS request to be acknowledged
by a USB device is outside of the xHC's ability to control.

To cancel a command, software will initialize a command
descriptor for the cancel command, and add it into a
cancel_cmd_list of xhci.

Sarah: Fixed missing newline on "Have the command ring been stopped?"
debugging statement.

This patch should be backported to kernels as old as 3.0, that contain
the commit 7ed603ecf8b68ab81f4c83097d3063d43ec73bb8 "xhci: Add an
assertion to check for virt_dev=0 bug." That commit papers over a NULL
pointer dereference, and this patch fixes the underlying issue that
caused the NULL pointer dereference.

Signed-off-by: Elric Fu <elricfu1@gmail.com>
Signed-off-by: Sarah Sharp <sarah.a.sharp@linux.intel.com>
Tested-by: Miroslav Sabljic <miroslav.sabljic@avl.com>
Cc: stable@vger.kernel.org

1 files changed, 7 insertions, 0 deletions

diff --git a/drivers/usb/host/xhci-mem.c b/drivers/usb/host/xhci-mem.c
index 77689bd64cac..487bc083dead 100644
--- a/drivers/usb/host/xhci-mem.c
+++ b/drivers/usb/host/xhci-mem.c
@@ -1772,6 +1772,7 @@ void xhci_mem_cleanup(struct xhci_hcd *xhci)
 {
         struct pci_dev  *pdev = to_pci_dev(xhci_to_hcd(xhci)->self.controller);
         struct dev_info *dev_info, *next;
+        struct xhci_cd  *cur_cd, *next_cd;
         unsigned long   flags;
         int size;
         int i, j, num_ports;
@@ -1795,6 +1796,11 @@ void xhci_mem_cleanup(struct xhci_hcd *xhci)
                 xhci_ring_free(xhci, xhci->cmd_ring);
         xhci->cmd_ring = NULL;
         xhci_dbg(xhci, "Freed command ring\n");
+        list_for_each_entry_safe(cur_cd, next_cd,
+                        &xhci->cancel_cmd_list, cancel_cmd_list) {
+                list_del(&cur_cd->cancel_cmd_list);
+                kfree(cur_cd);
+        }
 
         for (i = 1; i < MAX_HC_SLOTS; ++i)
                 xhci_free_virt_device(xhci, i);
@@ -2340,6 +2346,7 @@ int xhci_mem_init(struct xhci_hcd *xhci, gfp_t flags)
         xhci->cmd_ring = xhci_ring_alloc(xhci, 1, 1, TYPE_COMMAND, flags);
         if (!xhci->cmd_ring)
                 goto fail;
+        INIT_LIST_HEAD(&xhci->cancel_cmd_list);
         xhci_dbg(xhci, "Allocated command ring at %p\n", xhci->cmd_ring);
         xhci_dbg(xhci, "First segment DMA is 0x%llx\n",
                         (unsigned long long)xhci->cmd_ring->first_seg->dma);