@@ -1220,7 +1220,8 @@ int ieee80211_mesh_finish_csa(struct ieee80211_sub_if_data *sdata)
ifmsh->chsw_ttl = 0;
/* Remove the CSA and MCSP elements from the beacon */
- tmp_csa_settings = rcu_dereference(ifmsh->csa);
+ tmp_csa_settings = rcu_dereference_protected(ifmsh->csa,
+ lockdep_is_held(&sdata->wdev.mtx));
RCU_INIT_POINTER(ifmsh->csa, NULL);
if (tmp_csa_settings)
kfree_rcu(tmp_csa_settings, rcu_head);
@@ -1242,6 +1243,8 @@ int ieee80211_mesh_csa_beacon(struct ieee80211_sub_if_data *sdata,
struct mesh_csa_settings *tmp_csa_settings;
int ret = 0;
+ lockdep_assert_held(&sdata->wdev.mtx);
+
tmp_csa_settings = kmalloc(sizeof(*tmp_csa_settings),
GFP_ATOMIC);
if (!tmp_csa_settings)
ifmsh->csa is an RCU-protected pointer. The writer context in ieee80211_mesh_finish_csa() is already mutually exclusive with wdev->sdata.mtx, but the RCU checker did not know this. Use rcu_dereference_protected() to avoid a warning. fixes the following warning: [ 12.519089] ============================= [ 12.520042] WARNING: suspicious RCU usage [ 12.520652] 5.1.0-rc7-wt+ #16 Tainted: G W [ 12.521409] ----------------------------- [ 12.521972] net/mac80211/mesh.c:1223 suspicious rcu_dereference_check() usage! [ 12.522928] other info that might help us debug this: [ 12.523984] rcu_scheduler_active = 2, debug_locks = 1 [ 12.524855] 5 locks held by kworker/u8:2/152: [ 12.525438] #0: 00000000057be08c ((wq_completion)phy0){+.+.}, at: process_one_work+0x1a2/0x620 [ 12.526607] #1: 0000000059c6b07a ((work_completion)(&sdata->csa_finalize_work)){+.+.}, at: process_one_work+0x1a2/0x620 [ 12.528001] #2: 00000000f184ba7d (&wdev->mtx){+.+.}, at: ieee80211_csa_finalize_work+0x2f/0x90 [ 12.529116] #3: 00000000831a1f54 (&local->mtx){+.+.}, at: ieee80211_csa_finalize_work+0x47/0x90 [ 12.530233] #4: 00000000fd06f988 (&local->chanctx_mtx){+.+.}, at: ieee80211_csa_finalize_work+0x51/0x90 Signed-off-by: Thomas Pedersen <thomas@eero.com> --- v2: rcu_read_lock() doesn't make sense. Use rcu_dereference_protected() (Johannes) --- net/mac80211/mesh.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-)