From patchwork Sat Dec 4 06:35:45 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Luca Coelho X-Patchwork-Id: 12656313 X-Patchwork-Delegate: luca@coelho.fi Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 1F73CC433F5 for ; Sat, 4 Dec 2021 06:36:07 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S239878AbhLDGja (ORCPT ); Sat, 4 Dec 2021 01:39:30 -0500 Received: from paleale.coelho.fi ([176.9.41.70]:50278 "EHLO farmhouse.coelho.fi" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S238276AbhLDGj3 (ORCPT ); Sat, 4 Dec 2021 01:39:29 -0500 Received: from 91-156-5-105.elisa-laajakaista.fi ([91.156.5.105] helo=kveik.ger.corp.intel.com) by farmhouse.coelho.fi with esmtpsa (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.94.2) (envelope-from ) id 1mtOeQ-0017AH-Qg; Sat, 04 Dec 2021 08:36:03 +0200 From: Luca Coelho To: kvalo@codeaurora.org Cc: luca@coelho.fi, linux-wireless@vger.kernel.org Date: Sat, 4 Dec 2021 08:35:45 +0200 Message-Id: X-Mailer: git-send-email 2.33.1 In-Reply-To: <20211204063555.769822-1-luca@coelho.fi> References: <20211204063555.769822-1-luca@coelho.fi> MIME-Version: 1.0 Subject: [PATCH 02/12] iwlwifi: mvm: synchronize with FW after multicast commands Precedence: bulk List-ID: X-Mailing-List: linux-wireless@vger.kernel.org From: Johannes Berg If userspace installs a lot of multicast groups very quickly, then we may run out of command queue space as we send the updates in an asynchronous fashion (due to locking concerns), and the CPU can create them faster than the firmware can process them. This is true even when mac80211 has a work struct that gets scheduled. Fix this by synchronizing with the firmware after sending all those commands - outside of the iteration we can send a synchronous echo command that just has the effect of the CPU waiting for the prior asynchronous commands to finish. This also will cause fewer of the commands to be sent to the firmware overall, because the work will only run once when rescheduled multiple times while it's running. Link: https://bugzilla.kernel.org/show_bug.cgi?id=213649 Suggested-by: Emmanuel Grumbach Reported-by: Maximilian Ernestus Signed-off-by: Johannes Berg Signed-off-by: Luca Coelho --- .../net/wireless/intel/iwlwifi/mvm/mac80211.c | 17 +++++++++++++++++ 1 file changed, 17 insertions(+) diff --git a/drivers/net/wireless/intel/iwlwifi/mvm/mac80211.c b/drivers/net/wireless/intel/iwlwifi/mvm/mac80211.c index 20422e640059..9d84be991469 100644 --- a/drivers/net/wireless/intel/iwlwifi/mvm/mac80211.c +++ b/drivers/net/wireless/intel/iwlwifi/mvm/mac80211.c @@ -1710,6 +1710,7 @@ static void iwl_mvm_recalc_multicast(struct iwl_mvm *mvm) struct iwl_mvm_mc_iter_data iter_data = { .mvm = mvm, }; + int ret; lockdep_assert_held(&mvm->mutex); @@ -1719,6 +1720,22 @@ static void iwl_mvm_recalc_multicast(struct iwl_mvm *mvm) ieee80211_iterate_active_interfaces_atomic( mvm->hw, IEEE80211_IFACE_ITER_NORMAL, iwl_mvm_mc_iface_iterator, &iter_data); + + /* + * Send a (synchronous) ech command so that we wait for the + * multiple asynchronous MCAST_FILTER_CMD commands sent by + * the interface iterator. Otherwise, we might get here over + * and over again (by userspace just sending a lot of these) + * and the CPU can send them faster than the firmware can + * process them. + * Note that the CPU is still faster - but with this we'll + * actually send fewer commands overall because the CPU will + * not schedule the work in mac80211 as frequently if it's + * still running when rescheduled (possibly multiple times). + */ + ret = iwl_mvm_send_cmd_pdu(mvm, ECHO_CMD, 0, 0, NULL); + if (ret) + IWL_ERR(mvm, "Failed to synchronize multicast groups update\n"); } static u64 iwl_mvm_prepare_multicast(struct ieee80211_hw *hw,