x86/amd_node: Fix PCI device reference counting in amd_smn_init()grafted

The local "root" pointer is a temporary variable used during the device
search. Therefore, refcount related to the search iterators should be cleaned
up after the search is complete.

Use the __free() cleanup macro to ensure the refcount is decremented when the
temporary pointer goes out of scope.

Additionally, increment the refcount when caching a root pointer. This ensures
the in-use refcount is separate from the temporary search refcounting.

Finally, drop the redundant "root = NULL" before the second search loop. The
pci_get_class() iterator always decrements the refcount of its "from"
argument, so the first loop can only fall through with "root" already NULL.

Fixes: 0a4b61d9c2e4 ("x86/amd_node: Fix AMD root device caching")
Closes: https://sashiko.dev/#/patchset/20260806160159.230453-1-jason.andryuk%40amd.com
Reported-by: Sashiko <sashiko-bot@kernel.org>
Assisted-by: LLM
Signed-off-by: Yazen Ghannam <yazen.ghannam@amd.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: Mario Limonciello (AMD) <superm1@kernel.org>
Cc: <stable@kernel.org>
Link: https://patch.msgid.link/20260903154325.74343-1-yazen.ghannam@amd.com

1 files changed, 173 insertions, 0 deletions

diff --git a/net/mac802154/util.c b/net/mac802154/util.c
new file mode 100644
index 000000000..ebc9a8521
--- /dev/null
+++ b/net/mac802154/util.c
@@ -0,0 +1,173 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ *
+ * Authors:
+ * Alexander Aring <aar@pengutronix.de>
+ *
+ * Based on: net/mac80211/util.c
+ */
+
+#include "ieee802154_i.h"
+#include "driver-ops.h"
+
+/* privid for wpan_phys to determine whether they belong to us or not */
+const void *const mac802154_wpan_phy_privid = &mac802154_wpan_phy_privid;
+
+/**
+ * ieee802154_wake_queue - wake ieee802154 queue
+ * @hw: main hardware object
+ *
+ * Tranceivers usually have either one transmit framebuffer or one framebuffer
+ * for both transmitting and receiving. Hence, the core currently only handles
+ * one frame at a time for each phy, which means we had to stop the queue to
+ * avoid new skb to come during the transmission. The queue then needs to be
+ * woken up after the operation.
+ */
+static void ieee802154_wake_queue(struct ieee802154_hw *hw)
+{
+	struct ieee802154_local *local = hw_to_local(hw);
+	struct ieee802154_sub_if_data *sdata;
+
+	rcu_read_lock();
+	clear_bit(WPAN_PHY_FLAG_STATE_QUEUE_STOPPED, &local->phy->flags);
+	list_for_each_entry_rcu(sdata, &local->interfaces, list) {
+		if (!sdata->dev)
+			continue;
+
+		netif_wake_queue(sdata->dev);
+	}
+	rcu_read_unlock();
+}
+
+/**
+ * ieee802154_stop_queue - stop ieee802154 queue
+ * @hw: main hardware object
+ *
+ * Tranceivers usually have either one transmit framebuffer or one framebuffer
+ * for both transmitting and receiving. Hence, the core currently only handles
+ * one frame at a time for each phy, which means we need to tell upper layers to
+ * stop giving us new skbs while we are busy with the transmitted one. The queue
+ * must then be stopped before transmitting.
+ */
+static void ieee802154_stop_queue(struct ieee802154_hw *hw)
+{
+	struct ieee802154_local *local = hw_to_local(hw);
+	struct ieee802154_sub_if_data *sdata;
+
+	rcu_read_lock();
+	list_for_each_entry_rcu(sdata, &local->interfaces, list) {
+		if (!sdata->dev)
+			continue;
+
+		netif_stop_queue(sdata->dev);
+	}
+	rcu_read_unlock();
+}
+
+void ieee802154_hold_queue(struct ieee802154_local *local)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(&local->phy->queue_lock, flags);
+	if (!atomic_fetch_inc(&local->phy->hold_txs))
+		ieee802154_stop_queue(&local->hw);
+	spin_unlock_irqrestore(&local->phy->queue_lock, flags);
+}
+
+void ieee802154_release_queue(struct ieee802154_local *local)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(&local->phy->queue_lock, flags);
+	if (atomic_dec_and_test(&local->phy->hold_txs))
+		ieee802154_wake_queue(&local->hw);
+	spin_unlock_irqrestore(&local->phy->queue_lock, flags);
+}
+
+void ieee802154_disable_queue(struct ieee802154_local *local)
+{
+	struct ieee802154_sub_if_data *sdata;
+
+	rcu_read_lock();
+	list_for_each_entry_rcu(sdata, &local->interfaces, list) {
+		if (!sdata->dev)
+			continue;
+
+		netif_tx_disable(sdata->dev);
+	}
+	rcu_read_unlock();
+}
+
+enum hrtimer_restart ieee802154_xmit_ifs_timer(struct hrtimer *timer)
+{
+	struct ieee802154_local *local =
+		container_of(timer, struct ieee802154_local, ifs_timer);
+
+	ieee802154_release_queue(local);
+
+	return HRTIMER_NORESTART;
+}
+
+void ieee802154_xmit_complete(struct ieee802154_hw *hw, struct sk_buff *skb,
+			      bool ifs_handling)
+{
+	struct ieee802154_local *local = hw_to_local(hw);
+
+	local->tx_result = IEEE802154_SUCCESS;
+
+	if (ifs_handling) {
+		u8 max_sifs_size;
+
+		/* If transceiver sets CRC on his own we need to use lifs
+		 * threshold len above 16 otherwise 18, because it's not
+		 * part of skb->len.
+		 */
+		if (hw->flags & IEEE802154_HW_TX_OMIT_CKSUM)
+			max_sifs_size = IEEE802154_MAX_SIFS_FRAME_SIZE -
+					IEEE802154_FCS_LEN;
+		else
+			max_sifs_size = IEEE802154_MAX_SIFS_FRAME_SIZE;
+
+		if (skb->len > max_sifs_size)
+			hrtimer_start(&local->ifs_timer,
+				      hw->phy->lifs_period * NSEC_PER_USEC,
+				      HRTIMER_MODE_REL);
+		else
+			hrtimer_start(&local->ifs_timer,
+				      hw->phy->sifs_period * NSEC_PER_USEC,
+				      HRTIMER_MODE_REL);
+	} else {
+		ieee802154_release_queue(local);
+	}
+
+	dev_consume_skb_any(skb);
+	if (atomic_dec_and_test(&hw->phy->ongoing_txs))
+		wake_up(&hw->phy->sync_txq);
+}
+EXPORT_SYMBOL(ieee802154_xmit_complete);
+
+void ieee802154_xmit_error(struct ieee802154_hw *hw, struct sk_buff *skb,
+			   int reason)
+{
+	struct ieee802154_local *local = hw_to_local(hw);
+
+	local->tx_result = reason;
+	ieee802154_release_queue(local);
+	dev_kfree_skb_any(skb);
+	if (atomic_dec_and_test(&hw->phy->ongoing_txs))
+		wake_up(&hw->phy->sync_txq);
+}
+EXPORT_SYMBOL(ieee802154_xmit_error);
+
+void ieee802154_xmit_hw_error(struct ieee802154_hw *hw, struct sk_buff *skb)
+{
+	ieee802154_xmit_error(hw, skb, IEEE802154_SYSTEM_ERROR);
+}
+EXPORT_SYMBOL(ieee802154_xmit_hw_error);
+
+void ieee802154_stop_device(struct ieee802154_local *local)
+{
+	flush_workqueue(local->workqueue);
+	hrtimer_cancel(&local->ifs_timer);
+	drv_stop(local);
+}