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Thu, 15 Apr 2021 16:47:21 +0800 From: Ping-Ke Shih To: , CC: , , , , Subject: [PATCH 2/3] rtw88: Fix potential unrecoverable tx queue stop Date: Thu, 15 Apr 2021 16:47:02 +0800 Message-ID: <20210415084703.27255-3-pkshih@realtek.com> X-Mailer: git-send-email 2.21.0 In-Reply-To: <20210415084703.27255-1-pkshih@realtek.com> References: <20210415084703.27255-1-pkshih@realtek.com> MIME-Version: 1.0 X-Originating-IP: [172.21.69.146] X-ClientProxiedBy: RTEXMBS02.realtek.com.tw (172.21.6.95) To RTEXMBS04.realtek.com.tw (172.21.6.97) X-KSE-ServerInfo: RTEXMBS04.realtek.com.tw, 9 X-KSE-Antivirus-Interceptor-Info: scan successful X-KSE-Antivirus-Info: =?big5?b?Q2xlYW4sIGJhc2VzOiAyMDIxLzQvMTUgpFekyCAw?= =?big5?b?NjowMDowMA==?= X-KSE-Attachment-Filter-Triggered-Rules: Clean X-KSE-Attachment-Filter-Triggered-Filters: Clean X-KSE-BulkMessagesFiltering-Scan-Result: protection disabled X-KSE-AntiSpam-Outbound-Interceptor-Info: scan successful X-KSE-AntiSpam-Version: 5.9.20, Database issued on: 04/15/2021 08:05:31 X-KSE-AntiSpam-Status: KAS_STATUS_NOT_DETECTED X-KSE-AntiSpam-Method: none X-KSE-AntiSpam-Rate: 10 X-KSE-AntiSpam-Info: Lua profiles 163124 [Apr 15 2021] X-KSE-AntiSpam-Info: Version: 5.9.20.0 X-KSE-AntiSpam-Info: Envelope from: pkshih@realtek.com X-KSE-AntiSpam-Info: LuaCore: 442 442 b985cb57763b61d2a20abb585d5d4cc10c315b09 X-KSE-AntiSpam-Info: {Prob_from_in_msgid} X-KSE-AntiSpam-Info: {Tracking_from_domain_doesnt_match_to} X-KSE-AntiSpam-Info: d41d8cd98f00b204e9800998ecf8427e.com:7.1.1; 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127.0.0.199:7.1.2; realtek.com:7.1.1 X-KSE-AntiSpam-Info: {Track_Chinese_Simplified, headers_charset} X-KSE-AntiSpam-Info: Rate: 10 X-KSE-AntiSpam-Info: Status: not_detected X-KSE-AntiSpam-Info: Method: none X-KSE-AntiSpam-Info: Auth:dkim=none X-KSE-Antiphishing-Info: Clean X-KSE-Antiphishing-ScanningType: Heuristic X-KSE-Antiphishing-Method: None X-KSE-Antiphishing-Bases: 04/15/2021 08:12:00 Precedence: bulk List-ID: X-Mailing-List: linux-wireless@vger.kernel.org From: Yu-Yen Ting If there are lots of packets to be transmitted, the driver would check whether the available descriptors are sufficient according the read/write point of tx queue. Once the available descriptor is not enough, ieee80211_stop_queue is called. TX ISR, meanwhile, is releasing the tx resources after the packets are transmitted. This routine may call ieee80211_wake_queue by checking the available descriptor. The potential queue stop problem would occur when the tx queue is stopped due to the heavy traffic. Then thare is no chance to wake the queue up because the read point is not updated immediately, as a result, no more packets coulde be transmitted in this queue. This patch makes sure the ieee80211_wake_queue could be called properly and avoids the race condition when ring->r.rp, ring->queue_stopped are updated. Signed-off-by: Yu-Yen Ting Signed-off-by: Ping-Ke Shih --- drivers/net/wireless/realtek/rtw88/pci.c | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-) diff --git a/drivers/net/wireless/realtek/rtw88/pci.c b/drivers/net/wireless/realtek/rtw88/pci.c index b8115b31839e..adea3c7551ab 100644 --- a/drivers/net/wireless/realtek/rtw88/pci.c +++ b/drivers/net/wireless/realtek/rtw88/pci.c @@ -950,10 +950,12 @@ static int rtw_pci_tx_write(struct rtw_dev *rtwdev, return ret; ring = &rtwpci->tx_rings[queue]; + spin_lock_bh(&rtwpci->irq_lock); if (avail_desc(ring->r.wp, ring->r.rp, ring->r.len) < 2) { ieee80211_stop_queue(rtwdev->hw, skb_get_queue_mapping(skb)); ring->queue_stopped = true; } + spin_unlock_bh(&rtwpci->irq_lock); return 0; } @@ -968,7 +970,7 @@ static void rtw_pci_tx_isr(struct rtw_dev *rtwdev, struct rtw_pci *rtwpci, struct sk_buff *skb; u32 count; u32 bd_idx_addr; - u32 bd_idx, cur_rp; + u32 bd_idx, cur_rp, rp_idx; u16 q_map; ring = &rtwpci->tx_rings[hw_queue]; @@ -977,6 +979,7 @@ static void rtw_pci_tx_isr(struct rtw_dev *rtwdev, struct rtw_pci *rtwpci, bd_idx = rtw_read32(rtwdev, bd_idx_addr); cur_rp = bd_idx >> 16; cur_rp &= TRX_BD_IDX_MASK; + rp_idx = ring->r.rp; if (cur_rp >= ring->r.rp) count = cur_rp - ring->r.rp; else @@ -1000,12 +1003,15 @@ static void rtw_pci_tx_isr(struct rtw_dev *rtwdev, struct rtw_pci *rtwpci, } if (ring->queue_stopped && - avail_desc(ring->r.wp, ring->r.rp, ring->r.len) > 4) { + avail_desc(ring->r.wp, rp_idx, ring->r.len) > 4) { q_map = skb_get_queue_mapping(skb); ieee80211_wake_queue(hw, q_map); ring->queue_stopped = false; } + if (++rp_idx >= ring->r.len) + rp_idx = 0; + skb_pull(skb, rtwdev->chip->tx_pkt_desc_sz); info = IEEE80211_SKB_CB(skb);