From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751817AbcLCMjb (ORCPT ); Sat, 3 Dec 2016 07:39:31 -0500 Received: from mail-he1eur01on0108.outbound.protection.outlook.com ([104.47.0.108]:28928 "EHLO EUR01-HE1-obe.outbound.protection.outlook.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1750917AbcLCMj2 (ORCPT ); Sat, 3 Dec 2016 07:39:28 -0500 X-Greylist: delayed 18955 seconds by postgrey-1.27 at vger.kernel.org; Sat, 03 Dec 2016 07:39:27 EST Authentication-Results: spf=none (sender IP is ) smtp.mailfrom=bhuvanchandra.dv@toradex.com; Subject: Re: [PATCH] tty: serial: fsl_lpuart: fix del_timer_sync() vs timer routine deadlock To: Nikita Yushchenko , Stefan Agner References: <1480674490-24718-1-git-send-email-nikita.yoush@cogentembedded.com> <77e2726b8b84c55f9109ff18dfcfbbdf@agner.ch> <9ee78fcd-7aca-e2d3-4df1-fe65a512a0f5@toradex.com> <68d2fd35-834b-fe74-c9a2-719c7b62a83a@cogentembedded.com> 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1;VI1PR0501MB2397;7:J+ijbE9+cEGt/JazO9tkOpM2vkBTCisiMwYKRNFxsRq5FhyQN9GBgn6csvzlT/tk+ylOUf4xOhKONLQa2RZEIbf4BecdIWRwCx/g6H9b458ndLAdq6Kfe0UsDDifmi9dGjzTBzci8Ed57YI6LIX/daaLISk/1ItVUkHleCpHgrR4LH5+G94dYiEssqTszdEvK/8jeIqhSf2DTDqUpQ4srMScHan4oFyjpoAuTpBlXyBUXpqHChn5UbPrN1Al9BvZJ2G2Yxd51uRg148a3bWFa0zgLeZ2uAfxCnlye9ooSZLsbn+tgpfVd5uNam8dz60sNx28jhGuDqWnQPgY5qPlwrwZBvzCLY5Em4BaO+bctfVH4TX5U+lEgdUpwlyWaWyT4rx5i7ng4gAiy9/OJbPRTYY9hVMha6MUaY1iFNSP82k+NkzoZ+WcW/uje/DHKBcsGpU7kB5Eh1dm7Hy7sLzYog== X-OriginatorOrg: toradex.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 03 Dec 2016 10:07:12.3516 (UTC) X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted X-MS-Exchange-Transport-CrossTenantHeadersStamped: VI1PR0501MB2397 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 12/03/2016 02:25 PM, Nikita Yushchenko wrote: > > 03.12.2016 10:06, Bhuvanchandra DV пишет: >> On 12/03/2016 02:58 AM, Nikita Yushchenko wrote: >> >>>>> Problem found via lockdep: >>>>> >>>>> - lpuart_set_termios() calls del_timer_sync(&sport->lpuart_timer) while >>>>> holding sport->port.lock >>>>> >>>>> - sport->lpuart_timer routine is lpuart_timer_func() that calls >>>>> lpuart_copy_rx_to_tty() that acquires same lock. >>>>> >>>>> To fix, move Rx DMA stopping out of lock, as it already is in other >>>>> places >>>>> in the same file. >>>>> >>>>> While at it, also make Rx DMA start/stop code to look the same is in >>>>> other places in the same file. >>>> Yeah I saw that too, never really came around to look closer into it. >>>> >>>> Thanks for looking into it. >>>> >>>> You removed the check whether there was an old configuration, I think >>>> the idea of that was that we only resize DMA if it was configured >>>> differently before... >>> Per my code reading, checking for sport->lpuart_dma_rx_use should be >>> enough, this flag will be set only if DMA was previously enabled, >> The check is to make sure the reconfiguration of DMA is done only when >> the baudrate is altered. > Then, ok to use > > if (old && sport->lpuart_dma_rx_use) {...} > > in both places? Looks ok to me. -- Bhuvan