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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 08CACECAAD8 for ; Tue, 20 Sep 2022 12:25:55 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229678AbiITMZx (ORCPT ); Tue, 20 Sep 2022 08:25:53 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:40774 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230487AbiITMZw (ORCPT ); Tue, 20 Sep 2022 08:25:52 -0400 Received: from mga03.intel.com (mga03.intel.com [134.134.136.65]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id E8DEFA195; Tue, 20 Sep 2022 05:25:49 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1663676750; x=1695212750; h=date:from:to:cc:subject:in-reply-to:message-id: references:mime-version; bh=FBTXfJI31uC6GQV0ZGYB+frptD2zKMJQNM4znw8IIXw=; b=PPifY3ctE2c9IS9mpWOef+24BCnH7IAss/CJIrnzwBBsELlgZLlvUEpD mr58VofoTFc9hnAFEZnIiSMNgDdC/sFZEdgE9kDBEe55RNfoEyz2uw4US CIq7ASEktpR0xLz700zmwlpinWdyM8FyFUBqqliUDtWLPGvygsS8jXPI2 eWKg/TNav+/jAvzlsyyWVkQF/JfQBh4e8N2/TyI7HzvqLE0Up+oJAkcqF 5U4XRFlVaoNpZzmmCWKV2UknNNT0Yk785XXryeIF337bRwk5JttxsyyMJ P6iM27bNbnUF74toz/WlKSf5nzmdEUNJY8eWq/pkw5WpWhAVU1nsGXNPw Q==; X-IronPort-AV: E=McAfee;i="6500,9779,10476"; a="301056799" X-IronPort-AV: E=Sophos;i="5.93,330,1654585200"; d="scan'208";a="301056799" Received: from fmsmga003.fm.intel.com ([10.253.24.29]) by orsmga103.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 20 Sep 2022 05:25:49 -0700 X-IronPort-AV: E=Sophos;i="5.93,330,1654585200"; d="scan'208";a="707972470" Received: from bdallmer-mobl.ger.corp.intel.com ([10.252.59.238]) by fmsmga003-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 20 Sep 2022 05:25:47 -0700 Date: Tue, 20 Sep 2022 15:25:45 +0300 (EEST) From: =?ISO-8859-15?Q?Ilpo_J=E4rvinen?= To: Sherry Sun cc: gregkh@linuxfoundation.org, jirislaby@kernel.org, bhuvanchandra.dv@toradex.com, linux-serial@vger.kernel.org, linux-kernel@vger.kernel.org, linux-imx@nxp.com Subject: Re: [PATCH] tty: serial: fsl_lpuart: disable dma rx/tx use flags in lpuart_dma_shutdown In-Reply-To: <20220920111703.1532-1-sherry.sun@nxp.com> Message-ID: References: <20220920111703.1532-1-sherry.sun@nxp.com> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Precedence: bulk List-ID: X-Mailing-List: linux-serial@vger.kernel.org On Tue, 20 Sep 2022, Sherry Sun wrote: > lpuart_dma_shutdown tears down lpuart dma, but lpuart_flush_buffer can > still occur which in turn tries to access dma apis if lpuart_dma_tx_use > flag is true. At this point since dma is torn down, these dma apis can > abort. Set lpuart_dma_tx_use and the corresponding rx flag > lpuart_dma_rx_use to false in lpuart_dma_shutdown so that dmas are not > accessed after they are relinquished. > > Otherwise, when try to kill btattach, kernel may panic. This patch may > fix this issue. > root@imx8ulpevk:~# btattach -B /dev/ttyLP2 -S 115200 > ^C[ 90.182296] Internal error: synchronous external abort: 96000210 [#1] PREEMPT SMP > [ 90.189806] Modules linked in: moal(O) mlan(O) > [ 90.194258] CPU: 0 PID: 503 Comm: btattach Tainted: G O 5.15.32-06136-g34eecdf2f9e4 #37 > [ 90.203554] Hardware name: NXP i.MX8ULP 9X9 EVK (DT) > [ 90.208513] pstate: 600000c5 (nZCv daIF -PAN -UAO -TCO -DIT -SSBS BTYPE=--) > [ 90.215470] pc : fsl_edma3_disable_request+0x8/0x60 > [ 90.220358] lr : fsl_edma3_terminate_all+0x34/0x20c > [ 90.225237] sp : ffff800013f0bac0 > [ 90.228548] x29: ffff800013f0bac0 x28: 0000000000000001 x27: ffff000008404800 > [ 90.235681] x26: ffff000008404960 x25: ffff000008404a08 x24: ffff000008404a00 > [ 90.242813] x23: ffff000008404a60 x22: 0000000000000002 x21: 0000000000000000 > [ 90.249946] x20: ffff800013f0baf8 x19: ffff00000559c800 x18: 0000000000000000 > [ 90.257078] x17: 0000000000000000 x16: 0000000000000000 x15: 0000000000000000 > [ 90.264211] x14: 0000000000000003 x13: 0000000000000000 x12: 0000000000000040 > [ 90.271344] x11: ffff00000600c248 x10: ffff800013f0bb10 x9 : ffff000057bcb090 > [ 90.278477] x8 : fffffc0000241a08 x7 : ffff00000534ee00 x6 : ffff000008404804 > [ 90.285609] x5 : 0000000000000000 x4 : 0000000000000000 x3 : ffff0000055b3480 > [ 90.292742] x2 : ffff8000135c0000 x1 : ffff00000534ee00 x0 : ffff00000559c800 > [ 90.299876] Call trace: > [ 90.302321] fsl_edma3_disable_request+0x8/0x60 > [ 90.306851] lpuart_flush_buffer+0x40/0x160 > [ 90.311037] uart_flush_buffer+0x88/0x120 > [ 90.315050] tty_driver_flush_buffer+0x20/0x30 > [ 90.319496] hci_uart_flush+0x44/0x90 > [ 90.323162] +0x34/0x12c > [ 90.327253] tty_ldisc_close+0x38/0x70 > [ 90.331005] tty_ldisc_release+0xa8/0x190 > [ 90.335018] tty_release_struct+0x24/0x8c > [ 90.339022] tty_release+0x3ec/0x4c0 > [ 90.342593] __fput+0x70/0x234 > [ 90.345652] ____fput+0x14/0x20 > [ 90.348790] task_work_run+0x84/0x17c > [ 90.352455] do_exit+0x310/0x96c > [ 90.355688] do_group_exit+0x3c/0xa0 > [ 90.359259] __arm64_sys_exit_group+0x1c/0x20 > [ 90.363609] invoke_syscall+0x48/0x114 > [ 90.367362] el0_svc_common.constprop.0+0xd4/0xfc > [ 90.372068] do_el0_svc+0x2c/0x94 > [ 90.375379] el0_svc+0x28/0x80 > [ 90.378438] el0t_64_sync_handler+0xa8/0x130 > [ 90.382711] el0t_64_sync+0x1a0/0x1a4 > [ 90.386376] Code: 17ffffda d503201f d503233f f9409802 (b9400041) > [ 90.392467] ---[ end trace 2f60524b4a43f1f6 ]--- > [ 90.397073] note: btattach[503] exited with preempt_count 1 > [ 90.402636] Fixing recursive fault but reboot is needed! > > Fixes: 6250cc30c4c4 ("tty: serial: fsl_lpuart: Use scatter/gather DMA for Tx") > Signed-off-by: Thara Gopinath > Signed-off-by: Sherry Sun > --- > drivers/tty/serial/fsl_lpuart.c | 2 ++ > 1 file changed, 2 insertions(+) > > diff --git a/drivers/tty/serial/fsl_lpuart.c b/drivers/tty/serial/fsl_lpuart.c > index f21915015d67..064bd1f33c21 100644 > --- a/drivers/tty/serial/fsl_lpuart.c > +++ b/drivers/tty/serial/fsl_lpuart.c > @@ -1771,6 +1771,7 @@ static void lpuart_dma_shutdown(struct lpuart_port *sport) > if (sport->lpuart_dma_rx_use) { > del_timer_sync(&sport->lpuart_timer); > lpuart_dma_rx_free(&sport->port); > + sport->lpuart_dma_rx_use = false; > } > > if (sport->lpuart_dma_tx_use) { > @@ -1779,6 +1780,7 @@ static void lpuart_dma_shutdown(struct lpuart_port *sport) > sport->dma_tx_in_progress = false; > dmaengine_terminate_all(sport->dma_tx_chan); > } > + sport->lpuart_dma_tx_use = false; > } > > if (sport->dma_tx_chan) Isn't it still racy because lpuart_dma_shutdown() is called outside of port's lock? -- i.