usb: xhci: Avoid Stop Endpoint retry loop if the endpoint seems Running

[ Upstream commit 28a76fcc4c85dd39633fb96edb643c91820133e3 ]

Nothing prevents a broken HC from claiming that an endpoint is Running
and repeatedly rejecting Stop Endpoint with Context State Error.

Avoid infinite retries and give back cancelled TDs.

No such cases known so far, but HCs have bugs.

Signed-off-by: Michal Pecio <michal.pecio@gmail.com>
Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com>
Link: https://lore.kernel.org/r/20250311154551.4035726-4-mathias.nyman@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/drivers/usb/host/xhci-ring.c b/drivers/usb/host/xhci-ring.c
index 85a2b3ca05075af8e3ed905116ce1c6e0b046d29..0862fdd3e5682ded487d78918997fb1588ac819d 100644 (file)
--- a/drivers/usb/host/xhci-ring.c
+++ b/drivers/usb/host/xhci-ring.c
@@ -1175,16 +1175,19 @@ static void xhci_handle_cmd_stop_ep(struct xhci_hcd *xhci, int slot_id,
                         * Stopped state, but it will soon change to Running.
                         *
                         * Assume this bug on unexpected Stop Endpoint failures.
-                        * Keep retrying until the EP starts and stops again, on
-                        * chips where this is known to help. Wait for 100ms.
+                        * Keep retrying until the EP starts and stops again.
                         */
-                       if (time_is_before_jiffies(ep->stop_time + msecs_to_jiffies(100)))
-                               break;
                        fallthrough;
                case EP_STATE_RUNNING:
                        /* Race, HW handled stop ep cmd before ep was running */
                        xhci_dbg(xhci, "Stop ep completion ctx error, ctx_state %d\n",
                                        GET_EP_CTX_STATE(ep_ctx));
+                       /*
+                        * Don't retry forever if we guessed wrong or a defective HC never starts
+                        * the EP or says 'Running' but fails the command. We must give back TDs.
+                        */
+                       if (time_is_before_jiffies(ep->stop_time + msecs_to_jiffies(100)))
+                               break;
 
                        command = xhci_alloc_command(xhci, false, GFP_ATOMIC);
                        if (!command) {