From: Naftali Goldstein naftali.goldstein@intel.com
[ Upstream commit a2113cc44d4387a7c3ef3a9082d273524f9230ac ]
Consider the following flow: 1. Driver starts to sync the rx queues due to a delba. mvm->queue_sync_cookie=1. This rx-queues-sync is synchronous, so it doesn't increment the cookie until all rx queues handle the notification from FW. 2. During this time, driver starts to sync rx queues due to nssn sync required. The cookie's value is still 1, but it doesn't matter since this rx-queue-sync is non-synchronous so in the notification handler the cookie is ignored. What _does_ matter is that this flow increments the cookie to 2 immediately. Remember though that the FW won't start servicing this command until it's done with the previous one. 3. FW is still handling the first command, so it sends a notification with internal_notif->sync=1, and internal_notif->cookie=0, which triggers a WARN_ONCE.
The solution for this race is to only use the mvm->queue_sync_cookie in case of a synchronous sync-rx-queues. This way in step 2 the cookie's value won't change so we avoid the WARN.
The commit in the "fixes" field is the first commit to introduce non-synchronous sending of this command to FW.
Fixes: 3c514bf831ac ("iwlwifi: mvm: add a loose synchronization of the NSSN across Rx queues") Signed-off-by: Naftali Goldstein naftali.goldstein@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/mac80211.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-)
diff --git a/drivers/net/wireless/intel/iwlwifi/mvm/mac80211.c b/drivers/net/wireless/intel/iwlwifi/mvm/mac80211.c index a7bc00d1296fe..24a6beaacb156 100644 --- a/drivers/net/wireless/intel/iwlwifi/mvm/mac80211.c +++ b/drivers/net/wireless/intel/iwlwifi/mvm/mac80211.c @@ -5080,11 +5080,11 @@ void iwl_mvm_sync_rx_queues_internal(struct iwl_mvm *mvm, if (!iwl_mvm_has_new_rx_api(mvm)) return;
- notif->cookie = mvm->queue_sync_cookie; - - if (notif->sync) + if (notif->sync) { + notif->cookie = mvm->queue_sync_cookie; atomic_set(&mvm->queue_sync_counter, mvm->trans->num_rx_queues); + }
ret = iwl_mvm_notify_rx_queue(mvm, qmask, (u8 *)notif, size, !notif->sync); @@ -5104,7 +5104,8 @@ void iwl_mvm_sync_rx_queues_internal(struct iwl_mvm *mvm,
out: atomic_set(&mvm->queue_sync_counter, 0); - mvm->queue_sync_cookie++; + if (notif->sync) + mvm->queue_sync_cookie++; }
static void iwl_mvm_sync_rx_queues(struct ieee80211_hw *hw)