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, 102 insertions, 0 deletions

diff --git a/net/mac80211/eht.c b/net/mac80211/eht.c
new file mode 100644
index 000000000..23fe82df6
--- /dev/null
+++ b/net/mac80211/eht.c
@@ -0,0 +1,102 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * EHT handling
+ *
+ * Copyright(c) 2021-2026 Intel Corporation
+ */
+
+#include "driver-ops.h"
+#include "ieee80211_i.h"
+
+void
+ieee80211_eht_cap_ie_to_sta_eht_cap(struct ieee80211_sub_if_data *sdata,
+				    struct ieee80211_supported_band *sband,
+				    const u8 *he_cap_ie, u8 he_cap_len,
+				    const struct ieee80211_eht_cap_elem *eht_cap_ie_elem,
+				    u8 eht_cap_len,
+				    struct link_sta_info *link_sta)
+{
+	struct ieee80211_sta_eht_cap *eht_cap = &link_sta->pub->eht_cap;
+	struct ieee80211_he_cap_elem *he_cap_ie_elem = (void *)he_cap_ie;
+	u8 eht_ppe_size = 0;
+	u8 mcs_nss_size;
+	u8 eht_total_size = sizeof(eht_cap->eht_cap_elem);
+	u8 *pos = (u8 *)eht_cap_ie_elem;
+
+	memset(eht_cap, 0, sizeof(*eht_cap));
+
+	if (!eht_cap_ie_elem ||
+	    !ieee80211_get_eht_iftype_cap_vif(sband, &sdata->vif))
+		return;
+
+	mcs_nss_size = ieee80211_eht_mcs_nss_size(he_cap_ie_elem,
+						  &eht_cap_ie_elem->fixed,
+						  sdata->vif.type ==
+							NL80211_IFTYPE_STATION);
+
+	eht_total_size += mcs_nss_size;
+
+	/* Calculate the PPE thresholds length only if the header is present */
+	if (eht_cap_ie_elem->fixed.phy_cap_info[5] &
+			IEEE80211_EHT_PHY_CAP5_PPE_THRESHOLD_PRESENT) {
+		u16 eht_ppe_hdr;
+
+		if (eht_cap_len < eht_total_size + sizeof(u16))
+			return;
+
+		eht_ppe_hdr = get_unaligned_le16(eht_cap_ie_elem->optional + mcs_nss_size);
+		eht_ppe_size =
+			ieee80211_eht_ppe_size(eht_ppe_hdr,
+					       eht_cap_ie_elem->fixed.phy_cap_info);
+		eht_total_size += eht_ppe_size;
+
+		/* we calculate as if NSS > 8 are valid, but don't handle that */
+		if (eht_ppe_size > sizeof(eht_cap->eht_ppe_thres))
+			return;
+	}
+
+	if (eht_cap_len < eht_total_size)
+		return;
+
+	/* Copy the static portion of the EHT capabilities */
+	memcpy(&eht_cap->eht_cap_elem, pos, sizeof(eht_cap->eht_cap_elem));
+	pos += sizeof(eht_cap->eht_cap_elem);
+
+	/* Copy MCS/NSS which depends on the peer capabilities */
+	memset(&eht_cap->eht_mcs_nss_supp, 0,
+	       sizeof(eht_cap->eht_mcs_nss_supp));
+	memcpy(&eht_cap->eht_mcs_nss_supp, pos, mcs_nss_size);
+
+	if (eht_ppe_size)
+		memcpy(eht_cap->eht_ppe_thres,
+		       &eht_cap_ie_elem->optional[mcs_nss_size],
+		       eht_ppe_size);
+
+	eht_cap->has_eht = true;
+
+	/*
+	 * The MPDU length bits are reserved on all but 2.4 GHz and get set via
+	 * VHT (5 GHz) or HE (6 GHz) capabilities.
+	 */
+	if (sband->band != NL80211_BAND_2GHZ)
+		return;
+
+	switch (u8_get_bits(eht_cap->eht_cap_elem.mac_cap_info[0],
+			    IEEE80211_EHT_MAC_CAP0_MAX_MPDU_LEN_MASK)) {
+	case IEEE80211_EHT_MAC_CAP0_MAX_MPDU_LEN_11454:
+		link_sta->pub->agg.max_amsdu_len =
+			IEEE80211_MAX_MPDU_LEN_VHT_11454;
+		break;
+	case IEEE80211_EHT_MAC_CAP0_MAX_MPDU_LEN_7991:
+		link_sta->pub->agg.max_amsdu_len =
+			IEEE80211_MAX_MPDU_LEN_VHT_7991;
+		break;
+	case IEEE80211_EHT_MAC_CAP0_MAX_MPDU_LEN_3895:
+	default:
+		link_sta->pub->agg.max_amsdu_len =
+			IEEE80211_MAX_MPDU_LEN_VHT_3895;
+		break;
+	}
+
+	ieee80211_sta_recalc_aggregates(&link_sta->sta->sta);
+}