From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 3A5B9C5B578 for ; Mon, 8 Jul 2019 07:23:16 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 1DC7F2084A for ; Mon, 8 Jul 2019 07:23:16 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729410AbfGHHXN convert rfc822-to-8bit (ORCPT ); Mon, 8 Jul 2019 03:23:13 -0400 Received: from rtits2.realtek.com ([211.75.126.72]:37073 "EHLO rtits2.realtek.com.tw" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725977AbfGHHXN (ORCPT ); Mon, 8 Jul 2019 03:23:13 -0400 Authenticated-By: X-SpamFilter-By: BOX Solutions SpamTrap 5.62 with qID x687N1D1015818, This message is accepted by code: ctloc85258 Received: from mail.realtek.com (RTITCASV02.realtek.com.tw[172.21.6.19]) by rtits2.realtek.com.tw (8.15.2/2.57/5.78) with ESMTPS id x687N1D1015818 (version=TLSv1 cipher=DHE-RSA-AES256-SHA bits=256 verify=NOT); Mon, 8 Jul 2019 15:23:01 +0800 Received: from RTITMBSVM04.realtek.com.tw ([fe80::e404:880:2ef1:1aa1]) by RTITCASV02.realtek.com.tw ([::1]) with mapi id 14.03.0439.000; Mon, 8 Jul 2019 15:23:01 +0800 From: Tony Chuang To: Jian-Hong Pan , Kalle Valo , "David S . Miller" CC: "linux-wireless@vger.kernel.org" , "netdev@vger.kernel.org" , "linux-kernel@vger.kernel.org" , "linux@endlessm.com" , Daniel Drake , "stable@vger.kernel.org" Subject: RE: [PATCH] rtw88/pci: Rearrange the memory usage for skb in RX ISR Thread-Topic: [PATCH] rtw88/pci: Rearrange the memory usage for skb in RX ISR Thread-Index: AQHVNVeEOhZgR6M53kuE5XrXitIVDqbAR+xA Date: Mon, 8 Jul 2019 07:23:00 +0000 Message-ID: References: <20190708063252.4756-1-jian-hong@endlessm.com> In-Reply-To: <20190708063252.4756-1-jian-hong@endlessm.com> Accept-Language: zh-TW, en-US Content-Language: zh-TW X-MS-Has-Attach: X-MS-TNEF-Correlator: x-originating-ip: [172.21.68.183] Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 8BIT MIME-Version: 1.0 Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org > Subject: [PATCH] rtw88/pci: Rearrange the memory usage for skb in RX ISR nit, "rtw88: pci:" would be better. > > > When skb allocation fails and the "rx routine starvation" is hit, the > function returns immediately without updating the RX ring. At this > point, the RX ring may continue referencing an old skb which was already > handed off to ieee80211_rx_irqsafe(). When it comes to be used again, > bad things happen. > > This patch allocates a new skb first in RX ISR. If we don't have memory > available, we discard the current frame, allowing the existing skb to be > reused in the ring. Otherwise, we simplify the code flow and just hand > over the RX-populated skb over to mac80211. > > In addition, to fixing the kernel crash, the RX routine should now > generally behave better under low memory conditions. > > Buglink: https://bugzilla.kernel.org/show_bug.cgi?id=204053 > Signed-off-by: Jian-Hong Pan > Reviewed-by: Daniel Drake > Cc: > --- > drivers/net/wireless/realtek/rtw88/pci.c | 28 +++++++++++------------- > 1 file changed, 13 insertions(+), 15 deletions(-) > > diff --git a/drivers/net/wireless/realtek/rtw88/pci.c > b/drivers/net/wireless/realtek/rtw88/pci.c > index cfe05ba7280d..1bfc99ae6b84 100644 > --- a/drivers/net/wireless/realtek/rtw88/pci.c > +++ b/drivers/net/wireless/realtek/rtw88/pci.c > @@ -786,6 +786,15 @@ static void rtw_pci_rx_isr(struct rtw_dev *rtwdev, > struct rtw_pci *rtwpci, > rx_desc = skb->data; > chip->ops->query_rx_desc(rtwdev, rx_desc, &pkt_stat, &rx_status); > > + /* discard current skb if the new skb cannot be allocated as a > + * new one in rx ring later > + * */ nit, comment indentation. > + new = dev_alloc_skb(RTK_PCI_RX_BUF_SIZE); > + if (WARN(!new, "rx routine starvation\n")) { > + new = skb; > + goto next_rp; > + } > + > /* offset from rx_desc to payload */ > pkt_offset = pkt_desc_sz + pkt_stat.drv_info_sz + > pkt_stat.shift; > @@ -803,25 +812,14 @@ static void rtw_pci_rx_isr(struct rtw_dev *rtwdev, > struct rtw_pci *rtwpci, > skb_put(skb, pkt_stat.pkt_len); > skb_reserve(skb, pkt_offset); > > - /* alloc a smaller skb to mac80211 */ > - new = dev_alloc_skb(pkt_stat.pkt_len); > - if (!new) { > - new = skb; > - } else { > - skb_put_data(new, skb->data, skb->len); > - dev_kfree_skb_any(skb); > - } I am not sure if it's fine to deliver every huge SKB to mac80211. Because it will then be delivered to TCP/IP stack. Hence I think either it should be tested to know if the performance would be impacted or find out a more efficient way to send smaller SKB to mac80211 stack. > /* TODO: merge into rx.c */ > rtw_rx_stats(rtwdev, pkt_stat.vif, skb); > - memcpy(new->cb, &rx_status, sizeof(rx_status)); > - ieee80211_rx_irqsafe(rtwdev->hw, new); > + memcpy(skb->cb, &rx_status, sizeof(rx_status)); > + ieee80211_rx_irqsafe(rtwdev->hw, skb); > } > > - /* skb delivered to mac80211, alloc a new one in rx ring */ > - new = dev_alloc_skb(RTK_PCI_RX_BUF_SIZE); > - if (WARN(!new, "rx routine starvation\n")) > - return; > - > +next_rp: > + /* skb delivered to mac80211, attach the new one into rx ring */ > ring->buf[cur_rp] = new; > rtw_pci_reset_rx_desc(rtwdev, new, ring, cur_rp, buf_desc_sz); > -- Yan-Hsuan