From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from a27-55.smtp-out.us-west-2.amazonses.com ([54.240.27.55]) by merlin.infradead.org with esmtps (Exim 4.92.3 #3 (Red Hat Linux)) id 1kFJvK-0001fJ-Lt for ath10k@lists.infradead.org; Mon, 07 Sep 2020 16:23:26 +0000 From: Kalle Valo Subject: Re: [PATCH v3] ath10k: add flag to protect napi operation to avoid dead loop hang References: <1598617348-2325-1-git-send-email-wgong@codeaurora.org> Date: Mon, 7 Sep 2020 16:23:14 +0000 In-Reply-To: <1598617348-2325-1-git-send-email-wgong@codeaurora.org> (Wen Gong's message of "Fri, 28 Aug 2020 20:22:28 +0800") Message-ID: <010101746960efd0-9087ff0d-e24c-494d-90f5-d487b5322cf2-000000@us-west-2.amazonses.com> MIME-Version: 1.0 List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "ath10k" Errors-To: ath10k-bounces+kvalo=adurom.com@lists.infradead.org To: Wen Gong Cc: linux-wireless@vger.kernel.org, ath10k@lists.infradead.org Wen Gong writes: > It happened "Kernel panic - not syncing: hung_task: blocked tasks" when > test simulate crash and ifconfig down/rmmod meanwhile. > > Test steps: > > 1.Test commands, either can reproduce the hang for PCIe, SDIO and SNOC. > echo soft > /sys/kernel/debug/ieee80211/phy0/ath10k/simulate_fw_crash;sleep 0.05;ifconfig wlan0 down > echo soft > /sys/kernel/debug/ieee80211/phy0/ath10k/simulate_fw_crash;rmmod ath10k_sdio > echo hw-restart > /sys/kernel/debug/ieee80211/phy0/ath10k/simulate_fw_crash;rmmod ath10k_pci > > 2. dmesg: > [ 5622.548630] ath10k_sdio mmc1:0001:1: simulating soft firmware crash > [ 5622.655995] ieee80211 phy0: Hardware restart was requested > [ 5776.355164] INFO: task shill:1572 blocked for more than 122 seconds. > [ 5776.355687] INFO: task kworker/1:2:24437 blocked for more than 122 seconds. > [ 5776.359812] Kernel panic - not syncing: hung_task: blocked tasks > [ 5776.359836] CPU: 1 PID: 55 Comm: khungtaskd Tainted: G W 4.19.86 #137 > [ 5776.359846] Hardware name: MediaTek krane sku176 board (DT) > [ 5776.359855] Call trace: > [ 5776.359868] dump_backtrace+0x0/0x170 > [ 5776.359881] show_stack+0x20/0x2c > [ 5776.359896] dump_stack+0xd4/0x10c > [ 5776.359916] panic+0x12c/0x29c > [ 5776.359937] hung_task_panic+0x0/0x50 > [ 5776.359953] kthread+0x120/0x130 > [ 5776.359965] ret_from_fork+0x10/0x18 > [ 5776.359986] SMP: stopping secondary CPUs > [ 5776.360012] Kernel Offset: 0x141ea00000 from 0xffffff8008000000 > [ 5776.360026] CPU features: 0x0,2188200c > [ 5776.360035] Memory Limit: none > > command "ifconfig wlan0 down" or "rmmod ath10k_sdio" will be blocked > callstack of ifconfig: > [<0>] __switch_to+0x120/0x13c > [<0>] msleep+0x28/0x38 > [<0>] ath10k_sdio_hif_stop+0x24c/0x294 [ath10k_sdio] > [<0>] ath10k_core_stop+0x50/0x78 [ath10k_core] > [<0>] ath10k_halt+0x120/0x178 [ath10k_core] > [<0>] ath10k_stop+0x4c/0x8c [ath10k_core] > [<0>] drv_stop+0xe0/0x1e4 [mac80211] > [<0>] ieee80211_stop_device+0x48/0x54 [mac80211] > [<0>] ieee80211_do_stop+0x678/0x6f8 [mac80211] > [<0>] ieee80211_stop+0x20/0x30 [mac80211] > [<0>] __dev_close_many+0xb8/0x11c > [<0>] __dev_change_flags+0xe0/0x1d0 > [<0>] dev_change_flags+0x30/0x6c > [<0>] devinet_ioctl+0x370/0x564 > [<0>] inet_ioctl+0xdc/0x304 > [<0>] sock_do_ioctl+0x50/0x288 > [<0>] compat_sock_ioctl+0x1b4/0x1aac > [<0>] __se_compat_sys_ioctl+0x100/0x26fc > [<0>] __arm64_compat_sys_ioctl+0x20/0x2c > [<0>] el0_svc_common+0xa4/0x154 > [<0>] el0_svc_compat_handler+0x2c/0x38 > [<0>] el0_svc_compat+0x8/0x18 > [<0>] 0xffffffffffffffff > > callstack of rmmod: > [<0>] __switch_to+0x120/0x13c > [<0>] msleep+0x28/0x38 > [<0>] ath10k_sdio_hif_stop+0x294/0x31c [ath10k_sdio] > [<0>] ath10k_core_stop+0x50/0x78 [ath10k_core] > [<0>] ath10k_halt+0x120/0x178 [ath10k_core] > [<0>] ath10k_stop+0x4c/0x8c [ath10k_core] > [<0>] drv_stop+0xe0/0x1e4 [mac80211] > [<0>] ieee80211_stop_device+0x48/0x54 [mac80211] > [<0>] ieee80211_do_stop+0x678/0x6f8 [mac80211] > [<0>] ieee80211_stop+0x20/0x30 [mac80211] > [<0>] __dev_close_many+0xb8/0x11c > [<0>] dev_close_many+0x70/0x100 > [<0>] dev_close+0x4c/0x80 > [<0>] cfg80211_shutdown_all_interfaces+0x50/0xcc [cfg80211] > [<0>] ieee80211_remove_interfaces+0x58/0x1a0 [mac80211] > [<0>] ieee80211_unregister_hw+0x40/0x100 [mac80211] > [<0>] ath10k_mac_unregister+0x1c/0x44 [ath10k_core] > [<0>] ath10k_core_unregister+0x38/0x7c [ath10k_core] > [<0>] ath10k_sdio_remove+0x8c/0xd0 [ath10k_sdio] > [<0>] sdio_bus_remove+0x48/0x108 > [<0>] device_release_driver_internal+0x138/0x1ec > [<0>] driver_detach+0x6c/0xa8 > [<0>] bus_remove_driver+0x78/0xa8 > [<0>] driver_unregister+0x30/0x50 > [<0>] sdio_unregister_driver+0x28/0x34 > [<0>] cleanup_module+0x14/0x6bc [ath10k_sdio] > [<0>] __arm64_sys_delete_module+0x1e0/0x22c > [<0>] el0_svc_common+0xa4/0x154 > [<0>] el0_svc_compat_handler+0x2c/0x38 > [<0>] el0_svc_compat+0x8/0x18 > [<0>] 0xffffffffffffffff > > SNOC: > [ 647.156863] Call trace: > [ 647.162166] [] __switch_to+0x120/0x13c > [ 647.164512] [] __schedule+0x5ec/0x798 > [ 647.170062] [] schedule+0x74/0x94 > [ 647.175050] [] schedule_timeout+0x314/0x42c > [ 647.179874] [] schedule_timeout_uninterruptible+0x34/0x40 > [ 647.185780] [] msleep+0x28/0x38 > [ 647.192546] [] ath10k_snoc_hif_stop+0x4c/0x1e0 [ath10k_snoc] > [ 647.197439] [] ath10k_core_stop+0x50/0x7c [ath10k_core] > [ 647.204652] [] ath10k_halt+0x114/0x16c [ath10k_core] > [ 647.211420] [] ath10k_stop+0x4c/0x88 [ath10k_core] > [ 647.217865] [] drv_stop+0x110/0x244 [mac80211] > [ 647.224367] [] ieee80211_stop_device+0x48/0x54 [mac80211] > [ 647.230359] [] ieee80211_do_stop+0x6a4/0x73c [mac80211] > [ 647.237033] [] ieee80211_stop+0x20/0x30 [mac80211] > [ 647.243942] [] __dev_close_many+0xa0/0xfc > [ 647.250435] [] dev_close_many+0x70/0x100 > [ 647.255651] [] dev_close+0x4c/0x80 > [ 647.261244] [] cfg80211_shutdown_all_interfaces+0x44/0xcc [cfg80211] > [ 647.266383] [] ieee80211_remove_interfaces+0x58/0x1b4 [mac80211] > [ 647.274128] [] ieee80211_unregister_hw+0x50/0x120 [mac80211] > [ 647.281659] [] ath10k_mac_unregister+0x1c/0x44 [ath10k_core] > [ 647.288839] [] ath10k_core_unregister+0x48/0x90 [ath10k_core] > [ 647.296027] [] ath10k_snoc_remove+0x5c/0x150 [ath10k_snoc] > [ 647.303229] [] platform_drv_remove+0x28/0x50 > [ 647.310517] [] device_release_driver_internal+0x114/0x1b8 > [ 647.316257] [] driver_detach+0x6c/0xa8 > [ 647.323021] [] bus_remove_driver+0x78/0xa8 > [ 647.328571] [] driver_unregister+0x30/0x50 > [ 647.334213] [] platform_driver_unregister+0x1c/0x28 > [ 647.339876] [] cleanup_module+0x1c/0x120 [ath10k_snoc] > [ 647.346196] [] SyS_delete_module+0x1dc/0x22c > > PCIe: > [ 615.392770] rmmod D 0 3523 3458 0x00000080 > [ 615.392777] Call Trace: > [ 615.392784] __schedule+0x617/0x7d3 > [ 615.392791] ? __mod_timer+0x263/0x35c > [ 615.392797] schedule+0x62/0x72 > [ 615.392803] schedule_timeout+0x8d/0xf3 > [ 615.392809] ? run_local_timers+0x6b/0x6b > [ 615.392814] msleep+0x1b/0x22 > [ 615.392824] ath10k_pci_hif_stop+0x68/0xd6 [ath10k_pci] > [ 615.392844] ath10k_core_stop+0x44/0x67 [ath10k_core] > [ 615.392859] ath10k_halt+0x102/0x153 [ath10k_core] > [ 615.392873] ath10k_stop+0x38/0x75 [ath10k_core] > [ 615.392893] drv_stop+0x9a/0x13c [mac80211] > [ 615.392915] ieee80211_do_stop+0x772/0x7cd [mac80211] > [ 615.392937] ieee80211_stop+0x1a/0x1e [mac80211] > [ 615.392945] __dev_close_many+0x9e/0xf0 > [ 615.392952] dev_close_many+0x62/0xe8 > [ 615.392958] dev_close+0x54/0x7d > [ 615.392975] cfg80211_shutdown_all_interfaces+0x6e/0xa5 [cfg80211] > [ 615.393021] ieee80211_remove_interfaces+0x52/0x1aa [mac80211] > [ 615.393049] ieee80211_unregister_hw+0x54/0x136 [mac80211] > [ 615.393068] ath10k_mac_unregister+0x19/0x4a [ath10k_core] > [ 615.393091] ath10k_core_unregister+0x39/0x7e [ath10k_core] > [ 615.393104] ath10k_pci_remove+0x3d/0x7f [ath10k_pci] > [ 615.393117] pci_device_remove+0x41/0xa6 > [ 615.393129] device_release_driver_internal+0x123/0x1ec > [ 615.393140] driver_detach+0x60/0x90 > [ 615.393152] bus_remove_driver+0x72/0x9f > [ 615.393164] pci_unregister_driver+0x1e/0x87 > [ 615.393177] SyS_delete_module+0x1d7/0x277 > [ 615.393188] do_syscall_64+0x6b/0xf7 > [ 615.393199] entry_SYSCALL_64_after_hwframe+0x41/0xa6 > > The test command run simulate_fw_crash firstly and it call into > ath10k_sdio_hif_stop from ath10k_core_restart, then napi_disable > is called and bit NAPI_STATE_SCHED is set. After that, function > ath10k_sdio_hif_stop is called again from ath10k_stop by command > "ifconfig wlan0 down" or "rmmod ath10k_sdio", then command blocked. > > It is blocked by napi_synchronize, napi_disable will set bit with > NAPI_STATE_SCHED, and then napi_synchronize will enter dead loop > becuase bit NAPI_STATE_SCHED is set by napi_disable. > > function of napi_synchronize > static inline void napi_synchronize(const struct napi_struct *n) > { > if (IS_ENABLED(CONFIG_SMP)) > while (test_bit(NAPI_STATE_SCHED, &n->state)) > msleep(1); > else > barrier(); > } > > function of napi_disable > void napi_disable(struct napi_struct *n) > { > might_sleep(); > set_bit(NAPI_STATE_DISABLE, &n->state); > > while (test_and_set_bit(NAPI_STATE_SCHED, &n->state)) > msleep(1); > while (test_and_set_bit(NAPI_STATE_NPSVC, &n->state)) > msleep(1); > > hrtimer_cancel(&n->timer); > > clear_bit(NAPI_STATE_DISABLE, &n->state); > } > > Add flag for it avoid the hang and crash. > > Tested-on: QCA6174 hw3.2 SDIO WLAN.RMH.4.4.1-00049 > Tested-on: QCA6174 hw3.2 PCI WLAN.RM.4.4.1-00110-QCARMSWP-1 > Tested-on: WCN3990 hw1.0 SNOC hw1.0 WLAN.HL.3.1-01307.1-QCAHLSWMTPL-2 > > Signed-off-by: Wen Gong [...] > +void ath10k_core_napi_enable(struct ath10k *ar) > +{ > + if (ar->napi_enabled) > + return; > + > + napi_enable(&ar->napi); > + ar->napi_enabled = true; > +} > +EXPORT_SYMBOL(ath10k_core_napi_enable); > + > +void ath10k_core_napi_sync_disable(struct ath10k *ar) > +{ > + if (ar->napi_enabled) { > + napi_synchronize(&ar->napi); > + napi_disable(&ar->napi); > + ar->napi_enabled = false; > + } > +} > +EXPORT_SYMBOL(ath10k_core_napi_sync_disable); Just like with the recent firmware restart patch, isn't ar->napi_enabled racy? Wouldn't test_and_set_bit() and test_and_clear_bit() be safer? Or are we holding a lock? But then that should be documented with lockdep_assert_held(). -- https://wireless.wiki.kernel.org/en/developers/documentation/submittingpatches _______________________________________________ ath10k mailing list ath10k@lists.infradead.org http://lists.infradead.org/mailman/listinfo/ath10k