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=-5.2 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,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 9F466C04EB8 for ; Wed, 12 Dec 2018 09:08:25 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 63C0020849 for ; Wed, 12 Dec 2018 09:08:25 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="vyH/41ES" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 63C0020849 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726746AbeLLJIY (ORCPT ); Wed, 12 Dec 2018 04:08:24 -0500 Received: from merlin.infradead.org ([205.233.59.134]:55946 "EHLO merlin.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726242AbeLLJIX (ORCPT ); Wed, 12 Dec 2018 04:08:23 -0500 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=merlin.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=az6nWIJzub1fG/XLd9mMD/gUtKdjaDzbqD9w/4S8LlQ=; b=vyH/41ESX872uRVptejDH6ffo JcZgKMA97Sm09uVJZ5ku/hS3tQdzgSZnwBn1AkwbCf1nXn0B6tMLnqw64fzrHnDdAYzV1EoB2KqwL NQnOLK6ZgBO6ezh2Bz4ggFcF+OJ6hYMfNFwJpblgoyChZryFrANL4vedCRtFIcjB6daaoH/ZGfB4m lg/8bmOd2AXJPvgSAgVTu+uN4zP+5wvY4Svy29LEM2rLAOXbVq4UqQuz6/XV2qc8DdO8dAwXYiyGV rjkkNORrK4Asq17bJ+DzN2LqqAtTex2QuR31wpcd10j0gM26ImIRRG1pOe4SOBf17jfsaGWTR0IU7 mA8QHPdIg==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=hirez.programming.kicks-ass.net) by merlin.infradead.org with esmtpsa (Exim 4.90_1 #2 (Red Hat Linux)) id 1gX0Ui-0006U2-Cy; Wed, 12 Dec 2018 09:07:58 +0000 Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id 311242075BF39; Wed, 12 Dec 2018 10:07:51 +0100 (CET) Date: Wed, 12 Dec 2018 10:07:51 +0100 From: Peter Zijlstra To: Sergey Senozhatsky Cc: Dmitry Safonov , Jiri Slaby , kernel test robot , lkp@01.org, Greg Kroah-Hartman , Mikulas Patocka , LKML , linux-serial@vger.kernel.org, Sergey Senozhatsky , Petr Mladek , Steven Rostedt , Waiman Long Subject: Re: [LKP] [tty] c96cf923a9: WARNING:possible_circular_locking_dependency_detected Message-ID: <20181212090751.GU5289@hirez.programming.kicks-ass.net> References: <20181211091154.GL23332@shao2-debian> <2780774e-b397-dcc2-6950-cccb527d5014@arista.com> <20181212034252.GD431@jagdpanzerIV> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20181212034252.GD431@jagdpanzerIV> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Dec 12, 2018 at 12:42:52PM +0900, Sergey Senozhatsky wrote: > Something like this (not tested): > > --- > > drivers/tty/serial/serial_core.c | 14 ++++++++------ > 1 file changed, 8 insertions(+), 6 deletions(-) > > diff --git a/drivers/tty/serial/serial_core.c b/drivers/tty/serial/serial_core.c > index c439a5a1e6c0..64050f506348 100644 > --- a/drivers/tty/serial/serial_core.c > +++ b/drivers/tty/serial/serial_core.c > @@ -268,6 +268,7 @@ static void uart_shutdown(struct tty_struct *tty, struct uart_state *state) > struct uart_port *uport = uart_port_check(state); > struct tty_port *port = &state->port; > unsigned long flags = 0; > + char *xmit_buf = NULL; > > /* > * Set the TTY IO error marker > @@ -297,15 +298,16 @@ static void uart_shutdown(struct tty_struct *tty, struct uart_state *state) > */ > tty_port_set_suspended(port, 0); > > + uart_port_lock(state, flags); > + xmit_buf = state->xmit.buf; > + state->xmit.buf = NULL; > + uart_port_unlock(uport, flags); > + > /* > * Free the transmit buffer page. > */ > - uart_port_lock(state, flags); > - if (state->xmit.buf) { > - free_page((unsigned long)state->xmit.buf); > - state->xmit.buf = NULL; > - } > - uart_port_unlock(uport, flags); > + if (xmit_buf) > + free_page((unsigned long)xmit_buf); > } That looks sensible anyhow. One should strive to not do alloc or free under locks as much as possible anyway.