linux-kernel - [TESTPATCH] xhci: testpatch add temporary debug to cmd ring handling

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Message-ID: <20251107154604.1301374-1-mathias.nyman@linux.intel.com>
Date: Fri,  7 Nov 2025 17:46:03 +0200
From: Mathias Nyman <mathias.nyman@...ux.intel.com>
To: uttkarsh.aggarwal@....qualcomm.com
Cc: mathias.nyman@...ux.intel.com,
	gregkh@...uxfoundation.org,
	linux-kernel@...r.kernel.org,
	linux-usb@...r.kernel.org,
	wesley.cheng@....qualcomm.com
Subject: [TESTPATCH] xhci: testpatch add temporary debug to cmd ring handling

print messages with CMDDBG prefix if command ring is cleared
with pending commands, or fails to start due to sw state

TESTPATCH

Signed-off-by: Mathias Nyman <mathias.nyman@...ux.intel.com>
---
 drivers/usb/host/xhci-ring.c |  5 ++++-
 drivers/usb/host/xhci.c      | 16 ++++++++++++++++
 2 files changed, 20 insertions(+), 1 deletion(-)

diff --git a/drivers/usb/host/xhci-ring.c b/drivers/usb/host/xhci-ring.c
index b9e676d37a33..f8029d837428 100644
--- a/drivers/usb/host/xhci-ring.c
+++ b/drivers/usb/host/xhci-ring.c
@@ -421,8 +421,11 @@ static unsigned int xhci_ring_expansion_needed(struct xhci_hcd *xhci, struct xhc
 /* Ring the host controller doorbell after placing a command on the ring */
 void xhci_ring_cmd_db(struct xhci_hcd *xhci)
 {
-	if (!(xhci->cmd_ring_state & CMD_RING_STATE_RUNNING))
+	if (!(xhci->cmd_ring_state & CMD_RING_STATE_RUNNING)) {
+		xhci_err(xhci, "%pS Failed to start cmd ring, sw cmd_ring_state %d\n",
+			 __builtin_return_address(0), xhci->cmd_ring_state);
 		return;
+	}
 
 	xhci_dbg(xhci, "// Ding dong!\n");
 
diff --git a/drivers/usb/host/xhci.c b/drivers/usb/host/xhci.c
index d3063f796130..fe157813c136 100644
--- a/drivers/usb/host/xhci.c
+++ b/drivers/usb/host/xhci.c
@@ -504,6 +504,14 @@ static void xhci_set_cmd_ring_deq(struct xhci_hcd *xhci)
 	dma_addr_t deq_dma;
 	u64 crcr;
 
+	if (!list_empty(&xhci->cmd_list))
+		xhci_err(xhci, "%pS CMDDBG set cmd ring deq pendig commands\n",
+			 __builtin_return_address(0));
+	if (xhci->cmd_ring->dequeue != xhci->cmd_ring->enqueue)
+		xhci_err(xhci,"%pS CMDDBG set cmd ring deq: %p and enq %p mismatch\n",
+			 __builtin_return_address(0),
+			 xhci->cmd_ring->dequeue, xhci->cmd_ring->enqueue);
+
 	deq_dma = xhci_trb_virt_to_dma(xhci->cmd_ring->deq_seg, xhci->cmd_ring->dequeue);
 	deq_dma &= CMD_RING_PTR_MASK;
 
@@ -871,6 +879,14 @@ static void xhci_clear_command_ring(struct xhci_hcd *xhci)
 	struct xhci_segment *seg;
 
 	ring = xhci->cmd_ring;
+
+	if (!list_empty(&xhci->cmd_list))
+		xhci_err(xhci, "CMDDBG Clearing command ring with pendig commands\n");
+
+	if (ring->dequeue != ring->enqueue)
+		xhci_err(xhci,"CMDDBG clear cmd ring deq: %p and enq %p mismatch\n",
+			 ring->dequeue, ring->enqueue);
+
 	xhci_for_each_ring_seg(ring->first_seg, seg) {
 		/* erase all TRBs before the link */
 		memset(seg->trbs, 0, sizeof(union xhci_trb) * (TRBS_PER_SEGMENT - 1));
-- 
2.43.0