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=-8.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,USER_AGENT_MUTT autolearn=ham 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 28BADC10F11 for ; Sat, 13 Apr 2019 08:31:03 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 76968208E4 for ; Sat, 13 Apr 2019 08:31:02 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727353AbfDMIbB convert rfc822-to-8bit (ORCPT ); Sat, 13 Apr 2019 04:31:01 -0400 Received: from mx1.redhat.com ([209.132.183.28]:37550 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725776AbfDMIbB (ORCPT ); Sat, 13 Apr 2019 04:31:01 -0400 Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.phx2.redhat.com [10.5.11.14]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 41C92308B764; Sat, 13 Apr 2019 08:31:00 +0000 (UTC) Received: from localhost (unknown [10.43.2.181]) by smtp.corp.redhat.com (Postfix) with ESMTP id A8AF85D9C5; Sat, 13 Apr 2019 08:30:57 +0000 (UTC) Date: Sat, 13 Apr 2019 10:30:51 +0200 From: Stanislaw Gruszka To: Lorenzo Bianconi Cc: Lorenzo Bianconi , nbd@nbd.name, linux-wireless@vger.kernel.org Subject: Re: [PATCH] mt76: usb: fix possible memory leak during suspend/resume Message-ID: <20190413083050.GA7434@redhat.com> References: <20190412145442.GA2539@redhat.com> <20190412153509.GB3156@localhost.localdomain> <20190412162746.GC3156@localhost.localdomain> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: 8BIT In-Reply-To: <20190412162746.GC3156@localhost.localdomain> User-Agent: Mutt/1.11.3 (2019-02-01) X-Scanned-By: MIMEDefang 2.79 on 10.5.11.14 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.47]); Sat, 13 Apr 2019 08:31:00 +0000 (UTC) Sender: linux-wireless-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-wireless@vger.kernel.org On Fri, Apr 12, 2019 at 06:27:48PM +0200, Lorenzo Bianconi wrote: > > > On Fri, Apr 12, 2019 at 02:27:16PM +0200, Lorenzo Bianconi wrote: > > > > Disable mt76u_tx_tasklet at the end of mt76u_stop_queues in order to > > > > properly deallocate all pending skbs during suspend/resume phase > > > > > > On suspend/resume tx skb's are processed after tasklet_enable() > > > in resume callback. There is issue with device removal though > > > (during suspend or otherwise). > > > > Hi Stanislaw, > > > > I guess the right moment to deallocate the skbs is during suspend since resume > > can happen in very far future Yes, it's better to free on suspend, but in practice does not really matter since system is disabled till resume. > > > > Fixes: b40b15e1521f ("mt76: add usb support to mt76 layer") > > > > Signed-off-by: Lorenzo Bianconi > > > > --- > > > > drivers/net/wireless/mediatek/mt76/usb.c | 4 ++-- > > > > 1 file changed, 2 insertions(+), 2 deletions(-) > > > > > > > > diff --git a/drivers/net/wireless/mediatek/mt76/usb.c b/drivers/net/wireless/mediatek/mt76/usb.c > > > > index a3acc070063a..575207133775 100644 > > > > --- a/drivers/net/wireless/mediatek/mt76/usb.c > > > > +++ b/drivers/net/wireless/mediatek/mt76/usb.c > > > > @@ -842,10 +842,10 @@ static void mt76u_stop_tx(struct mt76_dev *dev) > > > > void mt76u_stop_queues(struct mt76_dev *dev) > > > > { > > > > tasklet_disable(&dev->usb.rx_tasklet); > > > > - tasklet_disable(&dev->usb.tx_tasklet); > > > > - > > > > mt76u_stop_rx(dev); > > > > + > > > > mt76u_stop_tx(dev); > > > > + tasklet_disable(&dev->usb.tx_tasklet); > > > > > > If tasklet is scheduled and we disable it and never enable, we end up > > > with infinite loop in tasklet_action_common(). This patch make the > > > problem less reproducible since tasklet_disable() is moved after > > > usb_kill_urb() -> tasklet_schedule(), but it is still possible. > > > > I can see the point here. Maybe we can just run tasklet_kill instead of > > tasklet_disable here (at least for tx one) I think you have right as tasklet_kill() will wait for scheduled tasklet . Originally in my patch (see below) I used wait_event as I thought tasklet_kill() may prevent scheduled tasklet to be executed (hence cause leak) but that seems to be not true. > I think it is enough even for rx side since usb_kill_urb() will wait the end of > mt76u_complete_rx() and tasklet_kill() will wait for the completion of > mt76u_rx_tasklet(). We will need to remove tasklet_enable in resume routines. No, because rx urb's are resubmitted on mt76u_rx_tasklet(). I use usb_poison_urb() to prevent that in my patch. Stanislaw commit 088b1209302e17cda688c9b562e18970c92823ac Author: Stanislaw Gruszka Date: Thu Apr 4 13:37:43 2019 +0200 mt76usb: fix tx/rx stop Disabling tasklets on stopping rx/tx is wrong. If blocked tasklet is scheduled and we remove device we get 100% cpu usage: PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND 9 root 20 0 0 0 0 R 93.8 0.0 1:47.19 ksoftirqd/0 by using memory after free and eventually crash: [ 2068.591964] RIP: 0010:tasklet_action_common.isra.17+0x66/0x100 [ 2068.591966] Code: 41 89 f5 eb 25 f0 48 0f ba 33 00 0f 83 b1 00 00 00 48 8b 7a 20 48 8b 42 18 e8 56 a3 b5 00 f0 80 23 fd 48 89 ea 48 85 ed 74 53 <48> 8b 2a 48 8d 5a 08 f0 48 0f ba 6a 08 01 72 0b 8b 42 10 85 c0 74 [ 2068.591968] RSP: 0018:ffff98758c34be58 EFLAGS: 00010206 [ 2068.591969] RAX: ffff98758e6966d0 RBX: ffff98756e69aef8 RCX: 0000000000000006 [ 2068.591970] RDX: 01060a053d060305 RSI: 0000000000000006 RDI: ffff98758e6966d0 [ 2068.591971] RBP: 01060a053d060305 R08: 0000000000000000 R09: 00000000000203c0 [ 2068.591971] R10: 000003ff65b34f08 R11: 0000000000000001 R12: ffff98758e6966d0 [ 2068.591972] R13: 0000000000000006 R14: 0000000000000040 R15: 0000000000000006 [ 2068.591974] FS: 0000000000000000(0000) GS:ffff98758e680000(0000) knlGS:0000000000000000 [ 2068.591975] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 2068.591975] CR2: 00002c5f73a6cc20 CR3: 00000002f920a001 CR4: 00000000003606e0 [ 2068.591977] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 2068.591978] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 2068.591978] Call Trace: [ 2068.591985] __do_softirq+0xe3/0x30a [ 2068.591989] ? sort_range+0x20/0x20 [ 2068.591990] run_ksoftirqd+0x26/0x40 [ 2068.591992] smpboot_thread_fn+0xc5/0x160 [ 2068.591995] kthread+0x112/0x130 [ 2068.591997] ? kthread_create_on_node+0x40/0x40 [ 2068.591998] ret_from_fork+0x35/0x40 [ 2068.591999] Modules linked in: ccm arc4 fuse rfcomm cmac bnep sunrpc snd_hda_codec_hdmi snd_soc_skl snd_soc_core snd_soc_acpi_intel_match snd_hda_codec_realtek snd_soc_acpi snd_hda_codec_generic snd_soc_skl_ipc snd_soc_sst_ipc snd_soc_sst_dsp snd_hda_ext_core iTCO_wdt snd_hda_intel intel_rapl iTCO_vendor_support x86_pkg_temp_thermal intel_powerclamp btusb mei_wdt coretemp btrtl snd_hda_codec btbcm btintel intel_cstate snd_hwdep intel_uncore uvcvideo snd_hda_core videobuf2_vmalloc videobuf2_memops intel_rapl_perf wmi_bmof videobuf2_v4l2 intel_wmi_thunderbolt snd_seq bluetooth joydev videobuf2_common snd_seq_device snd_pcm videodev media i2c_i801 snd_timer idma64 ecdh_generic intel_lpss_pci intel_lpss mei_me mei ucsi_acpi typec_ucsi processor_thermal_device intel_soc_dts_iosf intel_pch_thermal typec thinkpad_acpi wmi snd soundcore rfkill int3403_thermal int340x_thermal_zone int3400_thermal acpi_thermal_rel acpi_pad pcc_cpufreq uas usb_storage crc32c_intel i915 i2c_algo_bit nvme serio_raw [ 2068.592033] drm_kms_helper e1000e nvme_core drm video ipv6 [last unloaded: cfg80211] Fortunate thing is that this not happen frequently, as scheduling tasklet on blocked state is very exceptional, though might happen. Due to different RX/TX tasklet processing fix is different for those. For TX just wait until queues are empty. For RX assure rx_tasklet do fail to resubmit buffers by poisoning urb's and kill the tasklet. Signed-off-by: Stanislaw Gruszka diff --git a/drivers/net/wireless/mediatek/mt76/mac80211.c b/drivers/net/wireless/mediatek/mt76/mac80211.c index 15825e9a458f..7bf91566e212 100644 --- a/drivers/net/wireless/mediatek/mt76/mac80211.c +++ b/drivers/net/wireless/mediatek/mt76/mac80211.c @@ -384,7 +384,7 @@ void mt76_rx(struct mt76_dev *dev, enum mt76_rxq_id q, struct sk_buff *skb) } EXPORT_SYMBOL_GPL(mt76_rx); -static bool mt76_has_tx_pending(struct mt76_dev *dev) +bool mt76_has_tx_pending(struct mt76_dev *dev) { struct mt76_queue *q; int i; @@ -397,6 +397,7 @@ static bool mt76_has_tx_pending(struct mt76_dev *dev) return false; } +EXPORT_SYMBOL_GPL(mt76_has_tx_pending); void mt76_set_channel(struct mt76_dev *dev) { diff --git a/drivers/net/wireless/mediatek/mt76/mt76.h b/drivers/net/wireless/mediatek/mt76/mt76.h index b432da3f55c7..19d03294e678 100644 --- a/drivers/net/wireless/mediatek/mt76/mt76.h +++ b/drivers/net/wireless/mediatek/mt76/mt76.h @@ -682,6 +682,7 @@ void mt76_release_buffered_frames(struct ieee80211_hw *hw, u16 tids, int nframes, enum ieee80211_frame_release_type reason, bool more_data); +bool mt76_has_tx_pending(struct mt76_dev *dev); void mt76_set_channel(struct mt76_dev *dev); int mt76_get_survey(struct ieee80211_hw *hw, int idx, struct survey_info *survey); @@ -776,9 +777,9 @@ int mt76u_vendor_request(struct mt76_dev *dev, u8 req, void mt76u_single_wr(struct mt76_dev *dev, const u8 req, const u16 offset, const u32 val); int mt76u_init(struct mt76_dev *dev, struct usb_interface *intf); -int mt76u_submit_rx_buffers(struct mt76_dev *dev); int mt76u_alloc_queues(struct mt76_dev *dev); void mt76u_stop_queues(struct mt76_dev *dev); +int mt76u_start_queues(struct mt76_dev *dev); void mt76u_stop_stat_wk(struct mt76_dev *dev); void mt76u_queues_deinit(struct mt76_dev *dev); diff --git a/drivers/net/wireless/mediatek/mt76/mt76x0/usb.c b/drivers/net/wireless/mediatek/mt76/mt76x0/usb.c index 1ef00e971cfa..a27a3ae3dbf5 100644 --- a/drivers/net/wireless/mediatek/mt76/mt76x0/usb.c +++ b/drivers/net/wireless/mediatek/mt76/mt76x0/usb.c @@ -327,13 +327,10 @@ static int __maybe_unused mt76x0_resume(struct usb_interface *usb_intf) struct mt76_usb *usb = &dev->mt76.usb; int ret; - ret = mt76u_submit_rx_buffers(&dev->mt76); + ret = mt76u_start_queues(&dev->mt76); if (ret < 0) goto err; - tasklet_enable(&usb->rx_tasklet); - tasklet_enable(&usb->tx_tasklet); - ret = mt76x0u_init_hardware(dev); if (ret) goto err; diff --git a/drivers/net/wireless/mediatek/mt76/mt76x2/usb.c b/drivers/net/wireless/mediatek/mt76/mt76x2/usb.c index d08bb964966b..5450fb1c3f55 100644 --- a/drivers/net/wireless/mediatek/mt76/mt76x2/usb.c +++ b/drivers/net/wireless/mediatek/mt76/mt76x2/usb.c @@ -119,13 +119,10 @@ static int __maybe_unused mt76x2u_resume(struct usb_interface *intf) struct mt76_usb *usb = &dev->mt76.usb; int err; - err = mt76u_submit_rx_buffers(&dev->mt76); - if (err < 0) + err = mt76u_start_queues(&dev->mt76); + if (err) goto err; - tasklet_enable(&usb->rx_tasklet); - tasklet_enable(&usb->tx_tasklet); - err = mt76x2u_init_hardware(dev); if (err < 0) goto err; diff --git a/drivers/net/wireless/mediatek/mt76/usb.c b/drivers/net/wireless/mediatek/mt76/usb.c index a3acc070063a..8e32a60ac1c3 100644 --- a/drivers/net/wireless/mediatek/mt76/usb.c +++ b/drivers/net/wireless/mediatek/mt76/usb.c @@ -540,7 +540,7 @@ static void mt76u_rx_tasklet(unsigned long data) rcu_read_unlock(); } -int mt76u_submit_rx_buffers(struct mt76_dev *dev) +static int mt76u_submit_rx_buffers(struct mt76_dev *dev) { struct mt76_queue *q = &dev->q_rx[MT_RXQ_MAIN]; unsigned long flags; @@ -558,7 +558,6 @@ int mt76u_submit_rx_buffers(struct mt76_dev *dev) return err; } -EXPORT_SYMBOL_GPL(mt76u_submit_rx_buffers); static int mt76u_alloc_rx(struct mt76_dev *dev) { @@ -611,7 +610,9 @@ static void mt76u_stop_rx(struct mt76_dev *dev) int i; for (i = 0; i < q->ndesc; i++) - usb_kill_urb(q->entry[i].urb); + usb_poison_urb(q->entry[i].urb); + + tasklet_kill(&dev->usb.rx_tasklet); } static void mt76u_tx_tasklet(unsigned long data) @@ -830,20 +831,35 @@ static void mt76u_free_tx(struct mt76_dev *dev) static void mt76u_stop_tx(struct mt76_dev *dev) { struct mt76_queue *q; - int i, j; + int i, j, ret; for (i = 0; i < IEEE80211_NUM_ACS; i++) { q = dev->q_tx[i].q; for (j = 0; j < q->ndesc; j++) usb_kill_urb(q->entry[j].urb); } + + ret = wait_event_timeout(dev->tx_wait, !mt76_has_tx_pending(dev), HZ/5); + if (!ret) + dev_err(dev->dev, "timed out waiting for pending tx\n"); } -void mt76u_stop_queues(struct mt76_dev *dev) +int mt76u_start_queues(struct mt76_dev *dev) { - tasklet_disable(&dev->usb.rx_tasklet); - tasklet_disable(&dev->usb.tx_tasklet); + struct mt76_queue *q = &dev->q_rx[MT_RXQ_MAIN]; + int i; + + /* Nothing to do for TX */ + for (i = 0; i < q->ndesc; i++) + usb_unpoison_urb(q->entry[i].urb); + + return mt76u_submit_rx_buffers(dev); +} +EXPORT_SYMBOL_GPL(mt76u_start_queues); + +void mt76u_stop_queues(struct mt76_dev *dev) +{ mt76u_stop_rx(dev); mt76u_stop_tx(dev); }