From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: stable@vger.kernel.org
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	patches@lists.linux.dev,
	Takashi Sakamoto <o-takashi@sakamocchi.jp>,
	Sasha Levin <sashal@kernel.org>
Subject: [PATCH 6.12 1088/1376] firewire: core: consolidate port counting in build_tree()
Date: Sat, 12 Sep 2026 08:58:34 +0200
Message-ID: <20260912065631.811346644@linuxfoundation.org>
In-Reply-To: <20260912065607.535295758@linuxfoundation.org>
References: <20260912065607.535295758@linuxfoundation.org>
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6.12-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Takashi Sakamoto <o-takashi@sakamocchi.jp>

[ Upstream commit 87c48e54f28d410af0c12b5dd339307bb43abeea ]

The self ID sequence describes the state of each port for each PHY.
Currently, build_tree() counts the ports in two separate places.

Consolidate the port counting in one place.

Link: https://lore.kernel.org/r/20260811120928.700577-2-o-takashi@sakamocchi.jp
Signed-off-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>
Stable-dep-of: 05bfb1327dc5 ("firewire: core: fix memory leak in error path of build_tree()")
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/firewire/core-topology.c | 18 ++++++++++--------
 1 file changed, 10 insertions(+), 8 deletions(-)

diff --git a/drivers/firewire/core-topology.c b/drivers/firewire/core-topology.c
index 01c3304ea36c9..95579ec963062 100644
--- a/drivers/firewire/core-topology.c
+++ b/drivers/firewire/core-topology.c
@@ -119,8 +119,8 @@ static struct fw_node *build_tree(struct fw_card *card, const u32 *sid, int self
 
 	while (enumerator.quadlet_count > 0) {
 		unsigned int child_port_count = 0;
+		unsigned int parent_port_count = 0;
 		unsigned int total_port_count = 0;
-		unsigned int parent_count = 0;
 		unsigned int quadlet_count;
 		const u32 *self_id_sequence;
 		unsigned int port_capacity;
@@ -148,16 +148,19 @@ static struct fw_node *build_tree(struct fw_card *card, const u32 *sid, int self
 			switch (port_status) {
 			case PHY_PACKET_SELF_ID_PORT_STATUS_CHILD:
 				++child_port_count;
-				fallthrough;
+				break;
 			case PHY_PACKET_SELF_ID_PORT_STATUS_PARENT:
+				++parent_port_count;
+				break;
 			case PHY_PACKET_SELF_ID_PORT_STATUS_NCONN:
 				++total_port_count;
-				fallthrough;
+				break;
 			case PHY_PACKET_SELF_ID_PORT_STATUS_NONE:
 			default:
 				break;
 			}
 		}
+		total_port_count += child_port_count + parent_port_count;
 
 		if (phy_id != phy_packet_self_id_get_phy_id(self_id_sequence[0])) {
 			fw_err(card, "PHY ID mismatch in self ID: %d != %d\n",
@@ -203,7 +206,6 @@ static struct fw_node *build_tree(struct fw_card *card, const u32 *sid, int self
 				// we temporarily abuse node->color for remembering the entry in
 				// the node->ports array where the parent node should be.  Later,
 				// when we handle the parent node, we fix up the reference.
-				++parent_count;
 				node->color = port_index;
 				break;
 
@@ -223,10 +225,10 @@ static struct fw_node *build_tree(struct fw_card *card, const u32 *sid, int self
 
 		// Check that the node reports exactly one parent port, except for the root, which
 		// of course should have no parents.
-		if ((enumerator.quadlet_count == 0 && parent_count != 0) ||
-		    (enumerator.quadlet_count > 0 && parent_count != 1)) {
+		if ((enumerator.quadlet_count == 0 && parent_port_count != 0) ||
+		    (enumerator.quadlet_count > 0 && parent_port_count != 1)) {
 			fw_err(card, "parent port inconsistency for node %d: "
-			       "parent_count=%d\n", phy_id, parent_count);
+			       "parent_count=%d\n", phy_id, parent_port_count);
 			return NULL;
 		}
 
@@ -235,7 +237,7 @@ static struct fw_node *build_tree(struct fw_card *card, const u32 *sid, int self
 		list_add_tail(&node->link, &stack);
 		stack_depth += 1 - child_port_count;
 
-		if (node->phy_speed == SCODE_BETA && parent_count + child_port_count > 1)
+		if (node->phy_speed == SCODE_BETA && parent_port_count + child_port_count > 1)
 			beta_repeaters_present = true;
 
 		// If PHYs report different gap counts, set an invalid count which will force a gap
-- 
2.53.0