linux-kernel - [PATCH] xhci: Remove dead code in xhci_move_dequeue_past

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Message-Id: <20240524-xhci-deadcode-v1-1-a4453a756e0f@marcan.st>
Date: Fri, 24 May 2024 16:07:41 +0900
From: Hector Martin <marcan@...can.st>
To: Mathias Nyman <mathias.nyman@...el.com>, 
 Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc: linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org, 
 Hector Martin <marcan@...can.st>
Subject: [PATCH] xhci: Remove dead code in xhci_move_dequeue_past_td()

This codepath is trivially dead, since the function is never called with
a non-NULL td (the only callsite is immediately preceded by a NULL guard).

Signed-off-by: Hector Martin <marcan@...can.st>
---
 drivers/usb/host/xhci-ring.c | 19 -------------------
 1 file changed, 19 deletions(-)

diff --git a/drivers/usb/host/xhci-ring.c b/drivers/usb/host/xhci-ring.c
index 575f0fd9c9f1..f1ed728d9f8c 100644
--- a/drivers/usb/host/xhci-ring.c
+++ b/drivers/usb/host/xhci-ring.c
@@ -656,25 +656,6 @@ static int xhci_move_dequeue_past_td(struct xhci_hcd *xhci,
 			  stream_id);
 		return -ENODEV;
 	}
-	/*
-	 * A cancelled TD can complete with a stall if HW cached the trb.
-	 * In this case driver can't find td, but if the ring is empty we
-	 * can move the dequeue pointer to the current enqueue position.
-	 * We shouldn't hit this anymore as cached cancelled TRBs are given back
-	 * after clearing the cache, but be on the safe side and keep it anyway
-	 */
-	if (!td) {
-		if (list_empty(&ep_ring->td_list)) {
-			new_seg = ep_ring->enq_seg;
-			new_deq = ep_ring->enqueue;
-			new_cycle = ep_ring->cycle_state;
-			xhci_dbg(xhci, "ep ring empty, Set new dequeue = enqueue");
-			goto deq_found;
-		} else {
-			xhci_warn(xhci, "Can't find new dequeue state, missing td\n");
-			return -EINVAL;
-		}
-	}
 
 	hw_dequeue = xhci_get_hw_deq(xhci, dev, ep_index, stream_id);
 	new_seg = ep_ring->deq_seg;

---
base-commit: a38297e3fb012ddfa7ce0321a7e5a8daeb1872b6
change-id: 20240524-xhci-deadcode-8bf2ebe7609d

Best regards,
-- 
Hector Martin <marcan@...can.st>