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   1 From: Felix Fietkau <nbd@nbd.name>
   2 Date: Wed, 15 Feb 2023 15:21:37 +0100
   3 Subject: [PATCH] wifi: mac80211: fix race in mesh sequence number
   4  assignment
   5
   6 Since the sequence number is shared across different tx queues, it needs
   7 to be atomic in order to avoid accidental duplicate assignment
   8
   9 Signed-off-by: Felix Fietkau <nbd@nbd.name>
  10 ---
  11
  12 --- a/net/mac80211/ieee80211_i.h
  13 +++ b/net/mac80211/ieee80211_i.h
  14 @@ -696,7 +696,7 @@ struct ieee80211_if_mesh {
  15         struct mesh_stats mshstats;
  16         struct mesh_config mshcfg;
  17         atomic_t estab_plinks;
  18 -       u32 mesh_seqnum;
  19 +       atomic_t mesh_seqnum;
  20         bool accepting_plinks;
  21         int num_gates;
  22         struct beacon_data __rcu *beacon;
  23 --- a/net/mac80211/mesh.c
  24 +++ b/net/mac80211/mesh.c
  25 @@ -752,10 +752,8 @@ unsigned int ieee80211_new_mesh_header(s
  26
  27         meshhdr->ttl = sdata->u.mesh.mshcfg.dot11MeshTTL;
  28
  29 -       /* FIXME: racy -- TX on multiple queues can be concurrent */
  30 -       put_unaligned(cpu_to_le32(sdata->u.mesh.mesh_seqnum), &meshhdr->seqnum);
  31 -       sdata->u.mesh.mesh_seqnum++;
  32 -
  33 +       put_unaligned_le32(atomic_inc_return(&sdata->u.mesh.mesh_seqnum),
  34 +                          &meshhdr->seqnum);
  35         if (addr4or5 && !addr6) {
  36                 meshhdr->flags |= MESH_FLAGS_AE_A4;
  37                 memcpy(meshhdr->eaddr1, addr4or5, ETH_ALEN);