[PATCH 13/33] usb: xhci: rework xhci_free_segments_for_ring()

[Mathias Nyman <mathias.nyman@xxxxxxxxxxxxxxx>]

From: Niklas Neronin <niklas.neronin@xxxxxxxxxxxxxxx>

The segment list is only relevant within the context of the ring.
Thus, it is more logical to pass the ring itself when freeing all segments
from a ring, rather than passing the ring list.

Rename the function to "xhci_ring_segments_free" to align with the naming
convention of xhci_segment_free().

To make the freeing process more intuitive, free segments sequentially
from start to end (i.e., 0, 1, 2, 3, ...) instead of freeing the first
segment last (i.e., 1, 2, 3, ... 0).

Signed-off-by: Niklas Neronin <niklas.neronin@xxxxxxxxxxxxxxx>
Signed-off-by: Mathias Nyman <mathias.nyman@xxxxxxxxxxxxxxx>
---
 drivers/usb/host/xhci-mem.c | 21 +++++++++++----------
 1 file changed, 11 insertions(+), 10 deletions(-)

diff --git a/drivers/usb/host/xhci-mem.c b/drivers/usb/host/xhci-mem.c
index fa77a15dfde6..e46be4c49b2f 100644
--- a/drivers/usb/host/xhci-mem.c
+++ b/drivers/usb/host/xhci-mem.c
@@ -71,18 +71,18 @@ static void xhci_segment_free(struct xhci_hcd *xhci, struct xhci_segment *seg)
 	kfree(seg);
 }
 
-static void xhci_free_segments_for_ring(struct xhci_hcd *xhci,
-				struct xhci_segment *first)
+static void xhci_ring_segments_free(struct xhci_hcd *xhci, struct xhci_ring *ring)
 {
-	struct xhci_segment *seg;
+	struct xhci_segment *seg, *next;
+
+	ring->last_seg->next = NULL;
+	seg = ring->first_seg;
 
-	seg = first->next;
-	while (seg && seg != first) {
-		struct xhci_segment *next = seg->next;
+	while (seg) {
+		next = seg->next;
 		xhci_segment_free(xhci, seg);
 		seg = next;
 	}
-	xhci_segment_free(xhci, first);
 }
 
 /*
@@ -282,7 +282,7 @@ void xhci_ring_free(struct xhci_hcd *xhci, struct xhci_ring *ring)
 	if (ring->first_seg) {
 		if (ring->type == TYPE_STREAM)
 			xhci_remove_stream_mapping(ring);
-		xhci_free_segments_for_ring(xhci, ring->first_seg);
+		xhci_ring_segments_free(xhci, ring);
 	}
 
 	kfree(ring);
@@ -344,7 +344,8 @@ static int xhci_alloc_segments_for_ring(struct xhci_hcd *xhci, struct xhci_ring
 	return 0;
 
 free_segments:
-	xhci_free_segments_for_ring(xhci, ring->first_seg);
+	ring->last_seg = prev;
+	xhci_ring_segments_free(xhci, ring);
 	return -ENOMEM;
 }
 
@@ -433,7 +434,7 @@ int xhci_ring_expansion(struct xhci_hcd *xhci, struct xhci_ring *ring,
 	return 0;
 
 free_segments:
-	xhci_free_segments_for_ring(xhci, new_ring.first_seg);
+	xhci_ring_segments_free(xhci, &new_ring);
 	return ret;
 }
 
-- 
2.25.1