Return-path: Received: from mx1.redhat.com ([209.132.183.28]:41598 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751520AbdLSLeR (ORCPT ); Tue, 19 Dec 2017 06:34:17 -0500 From: Stanislaw Gruszka To: linux-wireless@vger.kernel.org Cc: Helmut Schaa , Enrico Mioso , Daniel Golle , Felix Fietkau , Stanislaw Gruszka Subject: [PATCH 2/2] rt2x00: do not pause queue unconditionally on error path Date: Tue, 19 Dec 2017 12:33:56 +0100 Message-Id: <1513683236-13402-2-git-send-email-sgruszka@redhat.com> (sfid-20171219_123420_174844_58B2216C) In-Reply-To: <1513683236-13402-1-git-send-email-sgruszka@redhat.com> References: <1513683236-13402-1-git-send-email-sgruszka@redhat.com> Sender: linux-wireless-owner@vger.kernel.org List-ID: Pausing queue without checking threshold is racy with txdone path. Moreover we do not need pause queue on any error, but only if queue is full - in case when we send RTS frame ( other cases of almost full queue are already handled in rt2x00queue_write_tx_frame() ). Patch fixes of theoretically possible problem of pausing empty queue. Signed-off-by: Stanislaw Gruszka --- drivers/net/wireless/ralink/rt2x00/rt2x00mac.c | 22 ++++++++++++++-------- 1 file changed, 14 insertions(+), 8 deletions(-) diff --git a/drivers/net/wireless/ralink/rt2x00/rt2x00mac.c b/drivers/net/wireless/ralink/rt2x00/rt2x00mac.c index c8a6f163102f..a971bc7a6b63 100644 --- a/drivers/net/wireless/ralink/rt2x00/rt2x00mac.c +++ b/drivers/net/wireless/ralink/rt2x00/rt2x00mac.c @@ -142,22 +142,28 @@ void rt2x00mac_tx(struct ieee80211_hw *hw, if (!rt2x00dev->ops->hw->set_rts_threshold && (tx_info->control.rates[0].flags & (IEEE80211_TX_RC_USE_RTS_CTS | IEEE80211_TX_RC_USE_CTS_PROTECT))) { - if (rt2x00queue_available(queue) <= 1) - goto exit_fail; + if (rt2x00queue_available(queue) <= 1) { + /* + * Recheck for full queue under lock to avoid race + * conditions with rt2x00lib_txdone(). + */ + spin_lock(&queue->tx_lock); + if (rt2x00queue_threshold(queue)) + rt2x00queue_pause_queue(queue); + spin_unlock(&queue->tx_lock); + + goto exit_free_skb; + } if (rt2x00mac_tx_rts_cts(rt2x00dev, queue, skb)) - goto exit_fail; + goto exit_free_skb; } if (unlikely(rt2x00queue_write_tx_frame(queue, skb, control->sta, false))) - goto exit_fail; + goto exit_free_skb; return; - exit_fail: - spin_lock(&queue->tx_lock); - rt2x00queue_pause_queue(queue); - spin_unlock(&queue->tx_lock); exit_free_skb: ieee80211_free_txskb(hw, skb); } -- 1.9.3