wifi: mac80211: Use struct instead of macro for PERR frame

The existing PERR_IE_* macros access HWMP PERR frame fields via hardcoded
byte offsets. Each PERR destination entry contains an optional 6-byte AE
(Address Extension) address followed by a reason code, making offset-based
access error-prone.

Introduce typed packed C structs to represent the PERR frame layout:
  - ieee80211_mesh_hwmp_perr: top-level frame containing TTL and
    destination count
  - ieee80211_mesh_hwmp_perr_dst: per-destination entry with optional AE
    address and variable-position reason code

Add ieee80211_mesh_hwmp_perr_get_rcode() to locate the reason code in
each destination entry depending on whether the AE flag is set.

This refactoring makes the PERR processing code consistent with the
struct-based approach adopted for PREQ and PREP in preceding patches.

Signed-off-by: Masashi Honma <masashi.honma@gmail.com>
Link: https://patch.msgid.link/20260529230952.124754-3-masashi.honma@gmail.com
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

diff --git a/include/linux/ieee80211-mesh.h b/include/linux/ieee80211-mesh.h
index 4ce4e47d6d0188b470339e34df83f157f48de4db..f709263c310b94d108db040ad396390ba4898583 100644 (file)
--- a/include/linux/ieee80211-mesh.h
+++ b/include/linux/ieee80211-mesh.h
@@ -71,6 +71,21 @@ struct ieee80211_mesh_hwmp_prep_bottom {
        __le32 orig_sn;
 } __packed;
 
+struct ieee80211_mesh_hwmp_perr_dst {
+       u8 flags;
+       u8 addr[ETH_ALEN];
+       __le32 sn;
+       /* optional Destination External Address */
+       u8 variable[];
+} __packed;
+
+struct ieee80211_mesh_hwmp_perr {
+       u8 ttl;
+       u8 number_of_dst;
+       /* Destinations */
+       u8 variable[];
+} __packed;
+
 /* Mesh flags */
 #define MESH_FLAGS_AE_A4       0x1
 #define MESH_FLAGS_AE_A5_A6    0x2
@@ -296,4 +311,51 @@ ieee80211_mesh_hwmp_prep_get_bottom(const u8 *ie)
                ieee80211_mesh_preq_prep_ae_enabled(ie) ? ETH_ALEN : 0];
 }
 
+static inline struct ieee80211_mesh_hwmp_perr_dst *
+ieee80211_mesh_hwmp_perr_get_dst(const u8 *ie, u8 dst_idx)
+{
+       struct ieee80211_mesh_hwmp_perr *perr_ie = (void *)ie;
+       struct ieee80211_mesh_hwmp_perr_dst *dst;
+       u8 *pos = perr_ie->variable;
+       int i;
+
+       for (i = 0; i < dst_idx + 1; i++) {
+               dst = (void *)pos;
+               pos += sizeof(struct ieee80211_mesh_hwmp_perr_dst) +
+                         ((dst->flags & AE_F) ? ETH_ALEN : 0)
+                         /* Destination External Address */ +
+                         2 /* Reason Code */;
+       }
+
+       return dst;
+}
+
+static inline u8 *
+ieee80211_mesh_hwmp_perr_get_addr(const u8 *ie, u8 dst_idx)
+{
+       struct ieee80211_mesh_hwmp_perr_dst *dst =
+               ieee80211_mesh_hwmp_perr_get_dst(ie, dst_idx);
+
+       return dst->addr;
+}
+
+static inline u32
+ieee80211_mesh_hwmp_perr_get_sn(const u8 *ie, u8 dst_idx)
+{
+       struct ieee80211_mesh_hwmp_perr_dst *dst =
+               ieee80211_mesh_hwmp_perr_get_dst(ie, dst_idx);
+
+       return le32_to_cpu(dst->sn);
+}
+
+static inline u16
+ieee80211_mesh_hwmp_perr_get_rcode(const u8 *ie, u8 dst_idx)
+{
+       struct ieee80211_mesh_hwmp_perr_dst *dst =
+               ieee80211_mesh_hwmp_perr_get_dst(ie, dst_idx);
+
+       return get_unaligned_le16(&dst->variable[
+               (dst->flags & AE_F) ? ETH_ALEN : 0]);
+}
+
 #endif /* LINUX_IEEE80211_MESH_H */

diff --git a/net/mac80211/mesh_hwmp.c b/net/mac80211/mesh_hwmp.c
index 39b782370df0a11e17ae6bca60d5af1e182b9e99..378338778a238257b957a9004a2db4d2af3a14b0 100644 (file)
--- a/net/mac80211/mesh_hwmp.c
+++ b/net/mac80211/mesh_hwmp.c
@@ -20,29 +20,7 @@
 
 static void mesh_queue_preq(struct mesh_path *, u8);
 
-static inline u32 u32_field_get(const u8 *preq_elem, int offset, bool ae)
-{
-       if (ae)
-               offset += 6;
-       return get_unaligned_le32(preq_elem + offset);
-}
-
-static inline u16 u16_field_get(const u8 *preq_elem, int offset, bool ae)
-{
-       if (ae)
-               offset += 6;
-       return get_unaligned_le16(preq_elem + offset);
-}
-
 /* HWMP IE processing macros */
-#define AE_F_SET(x)            (*x & AE_F)
-
-#define PERR_IE_TTL(x)         (*(x))
-#define PERR_IE_TARGET_FLAGS(x)        (*(x + 2))
-#define PERR_IE_TARGET_ADDR(x) (x + 3)
-#define PERR_IE_TARGET_SN(x)   u32_field_get(x, 9, 0)
-#define PERR_IE_TARGET_RCODE(x)        u16_field_get(x, 13, 0)
-
 #define MSEC_TO_TU(x) (x*1000/1024)
 #define SN_GT(x, y) ((s32)(y - x) < 0)
 #define SN_LT(x, y) ((s32)(x - y) < 0)
@@ -774,6 +752,7 @@ static void hwmp_perr_frame_process(struct ieee80211_sub_if_data *sdata,
                                    const u8 *perr_elem)
 {
        struct ieee80211_if_mesh *ifmsh = &sdata->u.mesh;
+       struct ieee80211_mesh_hwmp_perr *perr_elem_s = (void *)perr_elem;
        struct mesh_path *mpath;
        u8 ttl;
        const u8 *ta, *target_addr;
@@ -781,15 +760,15 @@ static void hwmp_perr_frame_process(struct ieee80211_sub_if_data *sdata,
        u16 target_rcode;
 
        ta = mgmt->sa;
-       ttl = PERR_IE_TTL(perr_elem);
+       ttl = perr_elem_s->ttl;
        if (ttl <= 1) {
                ifmsh->mshstats.dropped_frames_ttl++;
                return;
        }
        ttl--;
-       target_addr = PERR_IE_TARGET_ADDR(perr_elem);
-       target_sn = PERR_IE_TARGET_SN(perr_elem);
-       target_rcode = PERR_IE_TARGET_RCODE(perr_elem);
+       target_addr = ieee80211_mesh_hwmp_perr_get_addr(perr_elem, 0);
+       target_sn = ieee80211_mesh_hwmp_perr_get_sn(perr_elem, 0);
+       target_rcode = ieee80211_mesh_hwmp_perr_get_rcode(perr_elem, 0);
 
        rcu_read_lock();
        mpath = mesh_path_lookup(sdata, target_addr);