[ 024/147] xHCI: add aborting command ring function

Ben Hutchings
2012-10-14T14:44:32Z

From: Elric Fu <elricfu1@gmail.com>

commit b92cc66c047ff7cf587b318fe377061a353c120f upstream.

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>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---
drivers/usb/host/xhci-mem.c | 7 +++
drivers/usb/host/xhci-ring.c | 108 ++++++++++++++++++++++++++++++++++++++++++
drivers/usb/host/xhci.c | 2 +-
drivers/usb/host/xhci.h | 12 +++++
4 files changed, 128 insertions(+), 1 deletion(-)

--- a/drivers/usb/host/xhci-mem.c
+++ b/drivers/usb/host/xhci-mem.c
@@ -1680,6 +1680,7 @@ void xhci_mem_cleanup(struct xhci_hcd *x
{
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;
@@ -1701,6 +1702,11 @@ void xhci_mem_cleanup(struct xhci_hcd *x
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);
@@ -2246,6 +2252,7 @@ int xhci_mem_init(struct xhci_hcd *xhci,
xhci->cmd_ring = xhci_ring_alloc(xhci, 1, true, false, 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);
--- a/drivers/usb/host/xhci-ring.c
+++ b/drivers/usb/host/xhci-ring.c
@@ -318,6 +318,114 @@ void xhci_ring_cmd_db(struct xhci_hcd *x
xhci_readl(xhci, &xhci->dba->doorbell[0]);
}

+static int xhci_abort_cmd_ring(struct xhci_hcd *xhci)
+{
+ u64 temp_64;
+ int ret;
+
+ xhci_dbg(xhci, "Abort command ring\n");
+
+ if (!(xhci->cmd_ring_state & CMD_RING_STATE_RUNNING)) {
+ xhci_dbg(xhci, "The command ring isn't running, "
+ "Have the command ring been stopped?\n");
+ return 0;
+ }
+
+ temp_64 = xhci_read_64(xhci, &xhci->op_regs->cmd_ring);
+ if (!(temp_64 & CMD_RING_RUNNING)) {
+ xhci_dbg(xhci, "Command ring had been stopped\n");
+ return 0;
+ }
+ xhci->cmd_ring_state = CMD_RING_STATE_ABORTED;
+ xhci_write_64(xhci, temp_64 | CMD_RING_ABORT,
+ &xhci->op_regs->cmd_ring);
+
+ /* Section 4.6.1.2 of xHCI 1.0 spec says software should
+ * time the completion od all xHCI commands, including
+ * the Command Abort operation. If software doesn't see
+ * CRR negated in a timely manner (e.g. longer than 5
+ * seconds), then it should assume that the there are
+ * larger problems with the xHC and assert HCRST.
+ */
+ ret = handshake(xhci, &xhci->op_regs->cmd_ring,
+ CMD_RING_RUNNING, 0, 5 * 1000 * 1000);
+ if (ret < 0) {
+ xhci_err(xhci, "Stopped the command ring failed, "
+ "maybe the host is dead\n");
+ xhci->xhc_state |= XHCI_STATE_DYING;
+ xhci_quiesce(xhci);
+ xhci_halt(xhci);
+ return -ESHUTDOWN;
+ }
+
+ return 0;
+}
+
+static int xhci_queue_cd(struct xhci_hcd *xhci,
+ struct xhci_command *command,
+ union xhci_trb *cmd_trb)
+{
+ struct xhci_cd *cd;
+ cd = kzalloc(sizeof(struct xhci_cd), GFP_ATOMIC);
+ if (!cd)
+ return -ENOMEM;
+ INIT_LIST_HEAD(&cd->cancel_cmd_list);
+
+ cd->command = command;
+ cd->cmd_trb = cmd_trb;
+ list_add_tail(&cd->cancel_cmd_list, &xhci->cancel_cmd_list);
+
+ return 0;
+}
+
+/*
+ * Cancel the command which has issue.
+ *
+ * Some commands may hang due to waiting for acknowledgement from
+ * usb device. It is outside of the xHC's ability to control and
+ * will cause the command ring is blocked. When it occurs software
+ * should intervene to recover the command ring.
+ * See Section 4.6.1.1 and 4.6.1.2
+ */
+int xhci_cancel_cmd(struct xhci_hcd *xhci, struct xhci_command *command,
+ union xhci_trb *cmd_trb)
+{
+ int retval = 0;
+ unsigned long flags;
+
+ spin_lock_irqsave(&xhci->lock, flags);
+
+ if (xhci->xhc_state & XHCI_STATE_DYING) {
+ xhci_warn(xhci, "Abort the command ring,"
+ " but the xHCI is dead.\n");
+ retval = -ESHUTDOWN;
+ goto fail;
+ }
+
+ /* queue the cmd desriptor to cancel_cmd_list */
+ retval = xhci_queue_cd(xhci, command, cmd_trb);
+ if (retval) {
+ xhci_warn(xhci, "Queuing command descriptor failed.\n");
+ goto fail;
+ }
+
+ /* abort command ring */
+ retval = xhci_abort_cmd_ring(xhci);
+ if (retval) {
+ xhci_err(xhci, "Abort command ring failed\n");
+ if (unlikely(retval == -ESHUTDOWN)) {
+ spin_unlock_irqrestore(&xhci->lock, flags);
+ usb_hc_died(xhci_to_hcd(xhci)->primary_hcd);
+ xhci_dbg(xhci, "xHCI host controller is dead.\n");
+ return retval;
+ }
+ }
+
+fail:
+ spin_unlock_irqrestore(&xhci->lock, flags);
+ return retval;
+}
+
void xhci_ring_ep_doorbell(struct xhci_hcd *xhci,
unsigned int slot_id,
unsigned int ep_index,
--- a/drivers/usb/host/xhci.c
+++ b/drivers/usb/host/xhci.c
@@ -52,7 +52,7 @@ MODULE_PARM_DESC(link_quirk, "Don't clea
* handshake done). There are two failure modes: "usec" have passed (major
* hardware flakeout), or the register reads as all-ones (hardware removed).
*/
-static int handshake(struct xhci_hcd *xhci, void __iomem *ptr,
+int handshake(struct xhci_hcd *xhci, void __iomem *ptr,
u32 mask, u32 done, int usec)
{
u32 result;
--- a/drivers/usb/host/xhci.h
+++ b/drivers/usb/host/xhci.h
@@ -1255,6 +1255,13 @@ struct xhci_td {
union xhci_trb *last_trb;
};

+/* command descriptor */
+struct xhci_cd {
+ struct list_head cancel_cmd_list;
+ struct xhci_command *command;
+ union xhci_trb *cmd_trb;
+};
+
struct xhci_dequeue_state {
struct xhci_segment *new_deq_seg;
union xhci_trb *new_deq_ptr;
@@ -1406,6 +1413,7 @@ struct xhci_hcd {
#define CMD_RING_STATE_RUNNING (1 << 0)
#define CMD_RING_STATE_ABORTED (1 << 1)
#define CMD_RING_STATE_STOPPED (1 << 2)
+ struct list_head cancel_cmd_list;
unsigned int cmd_ring_reserved_trbs;
struct xhci_ring *event_ring;
struct xhci_erst erst;
@@ -1670,6 +1678,8 @@ static inline void xhci_unregister_pci(v

/* xHCI host controller glue */
typedef void (*xhci_get_quirks_t)(struct device *, struct xhci_hcd *);
+int handshake(struct xhci_hcd *xhci, void __iomem *ptr,
+ u32 mask, u32 done, int usec);
void xhci_quiesce(struct xhci_hcd *xhci);
int xhci_halt(struct xhci_hcd *xhci);
int xhci_reset(struct xhci_hcd *xhci);
@@ -1760,6 +1770,8 @@ void xhci_queue_config_ep_quirk(struct x
unsigned int slot_id, unsigned int ep_index,
struct xhci_dequeue_state *deq_state);
void xhci_stop_endpoint_command_watchdog(unsigned long arg);
+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);