From patchwork Sat Dec 15 09:03:08 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Luca Coelho X-Patchwork-Id: 10732055 X-Patchwork-Delegate: johannes@sipsolutions.net Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id BEE5813AD for ; Sat, 15 Dec 2018 09:03:39 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id A93651FFBD for ; Sat, 15 Dec 2018 09:03:39 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 9D48229179; Sat, 15 Dec 2018 09:03:39 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-7.9 required=2.0 tests=BAYES_00,MAILING_LIST_MULTI, RCVD_IN_DNSWL_HI autolearn=ham version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 4969C1FFBD for ; Sat, 15 Dec 2018 09:03:39 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730036AbeLOJDi (ORCPT ); Sat, 15 Dec 2018 04:03:38 -0500 Received: from paleale.coelho.fi ([176.9.41.70]:42226 "EHLO farmhouse.coelho.fi" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1729029AbeLOJDh (ORCPT ); Sat, 15 Dec 2018 04:03:37 -0500 Received: from 91-156-4-241.elisa-laajakaista.fi ([91.156.4.241] helo=redipa.ger.corp.intel.com) by farmhouse.coelho.fi with esmtpsa (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.91) (envelope-from ) id 1gY5rD-0002oc-T7; Sat, 15 Dec 2018 11:03:36 +0200 From: Luca Coelho To: johannes@sipsolutions.net Cc: linux-wireless@vger.kernel.org, Johannes Berg , Luca Coelho Date: Sat, 15 Dec 2018 11:03:08 +0200 Message-Id: <20181215090325.31604-8-luca@coelho.fi> X-Mailer: git-send-email 2.19.2 In-Reply-To: <20181215090325.31604-1-luca@coelho.fi> References: <20181215090325.31604-1-luca@coelho.fi> MIME-Version: 1.0 Subject: [PATCH 07/24] mac80211: document RCU requirements for ieee80211_tx_dequeue() Sender: linux-wireless-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-wireless@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP From: Johannes Berg In the iwlwifi conversion, we sometimes call this from outside of the wake_tx_queue() method, and in those cases must be in an RCU critical section. Document this requirement. Signed-off-by: Johannes Berg Signed-off-by: Luca Coelho --- include/net/mac80211.h | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/include/net/mac80211.h b/include/net/mac80211.h index 1553152b77e0..40ad390f0f6a 100644 --- a/include/net/mac80211.h +++ b/include/net/mac80211.h @@ -6106,6 +6106,14 @@ void ieee80211_unreserve_tid(struct ieee80211_sta *sta, u8 tid); * @txq: pointer obtained from station or virtual interface * * Returns the skb if successful, %NULL if no frame was available. + * + * Note that this must be called in an rcu_read_lock() critical section, + * which can only be released after the SKB was handled. Some pointers in + * skb->cb, e.g. the key pointer, are protected by by RCU and thus the + * critical section must persist not just for the duration of this call + * but for the duration of the frame handling. + * However, also note that while in the wake_tx_queue() method, + * rcu_read_lock() is already held. */ struct sk_buff *ieee80211_tx_dequeue(struct ieee80211_hw *hw, struct ieee80211_txq *txq);