[PATCH 4.19 029/243] iwlwifi: mvm: synchronize TID queue removal

Greg Kroah-Hartman
2019-12-11T15:17:42Z

From: Johannes Berg <johannes.berg@intel.com>

[ Upstream commit 06bc6f6ed4ae0246a5e52094d1be90906a1361c7 ]

When we mark a TID as no longer having a queue, there's no
guarantee the TX path isn't using this txq_id right now,
having accessed it just before we reset the value. To fix
this, add synchronize_net() when we change the TIDs from
having a queue to not having one, so that we can then be
sure that the TX path is no longer accessing that queue.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Luca Coelho <luciano.coelho@intel.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/net/wireless/intel/iwlwifi/mvm/sta.c | 10 ++++++++++
1 file changed, 10 insertions(+)

diff --git a/drivers/net/wireless/intel/iwlwifi/mvm/sta.c b/drivers/net/wireless/intel/iwlwifi/mvm/sta.c
index 04ea516bddcc0..e850aa504b608 100644
--- a/drivers/net/wireless/intel/iwlwifi/mvm/sta.c
+++ b/drivers/net/wireless/intel/iwlwifi/mvm/sta.c
@@ -440,6 +440,16 @@ static int iwl_mvm_remove_sta_queue_marking(struct iwl_mvm *mvm, int queue)

rcu_read_unlock();

+ /*
+ * The TX path may have been using this TXQ_ID from the tid_data,
+ * so make sure it's no longer running so that we can safely reuse
+ * this TXQ later. We've set all the TIDs to IWL_MVM_INVALID_QUEUE
+ * above, but nothing guarantees we've stopped using them. Thus,
+ * without this, we could get to iwl_mvm_disable_txq() and remove
+ * the queue while still sending frames to it.
+ */
+ synchronize_net();
+
return disable_agg_tids;
}

--
2.20.1