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=-5.1 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE, SPF_PASS,USER_AGENT_SANE_1 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 EC613C43603 for ; Thu, 5 Dec 2019 01:00:59 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id BDC8422525 for ; Thu, 5 Dec 2019 01:00:59 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="XS2aL1cc" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728570AbfLEBA6 (ORCPT ); Wed, 4 Dec 2019 20:00:58 -0500 Received: from mail-pf1-f196.google.com ([209.85.210.196]:40615 "EHLO mail-pf1-f196.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728011AbfLEBA6 (ORCPT ); Wed, 4 Dec 2019 20:00:58 -0500 Received: by mail-pf1-f196.google.com with SMTP id q8so721077pfh.7 for ; Wed, 04 Dec 2019 17:00:58 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to:user-agent; bh=8ft6UARj55cMd5qKu+UNVgACeCf359Q/Ufw3Kj1aax8=; b=XS2aL1cceootJu+8FQuJMtqkGMtj0Fgbf3se6DHlc538wfiKjstQwEO1qt9w5qcZqn 8z9kZdyiLpr4cHQ/qxHEYM8zE7dJHwHgLrYernfV/4WFWbdTtuxanpZlw57dOyX4FHTl lucDYm4dGq7nFKqEfG5WAvpxvL23Jb9bqm3wCvjdpaK7guVMDRZZf3oJ691mCiXG3hOP NkWxffEqup0LLm1myeVyBtQ4POQDBgELbyytAxBpdUPnjGz2LsvGqPaGzAEpxcMS1vqC SO4FjxfkCcrprvxg6wbqThuSC9BX5sgyC3UWhTyUa1xLUaI9BsUAHb72qtHR9WhGwvHZ fVag== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to:user-agent; bh=8ft6UARj55cMd5qKu+UNVgACeCf359Q/Ufw3Kj1aax8=; b=BuE3NyG34lB0c62HUQJ92npUIZfU1dAZb1BkfEst9+noLZXkeM9PldDlpGPIuQNi8r sw5zkUNNeq0p1G03W/p0awHTEokaBX4jC1svi4JetZlAGedMIjDzJ5nywwE0rZHJ47JF MRb3u/xRH8XlGyiHLM7EFm1abKlUJKKeKpoSH2eIRfLWVGR+FSVUDxFvhkPEEApC/hX8 6diJD5nYRPkqScO4Kd72mrjsVAgr1zDMpXaBNdh9W4tp40un029qgcvZJa8U2I1CdscL DPfKdsT7Yd9n5a1z+fyUtjl6vwEfNfGsMjjth+ORNtIP4bBuO2fo1GAlz/aect0rXPYB KZUQ== X-Gm-Message-State: APjAAAX30NPFYDCHWUZbjnk0TlDdNoijpwjKWsEY+DdQfXpObnv9mscq kFebwog5eC89GFXM62ew0fA= X-Google-Smtp-Source: APXvYqyPhn14pl3Csqr/dBGwcPGc1y+PbNIl6fcKXvdKmyD9naKGcJbylv0QHX7gWswMN56VjztUew== X-Received: by 2002:a63:2ac2:: with SMTP id q185mr6593367pgq.417.1575507657801; Wed, 04 Dec 2019 17:00:57 -0800 (PST) Received: from localhost ([2401:fa00:8f:203:250d:e71d:5a0a:9afe]) by smtp.gmail.com with ESMTPSA id y22sm9155228pfn.122.2019.12.04.17.00.56 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 04 Dec 2019 17:00:56 -0800 (PST) Date: Thu, 5 Dec 2019 10:00:55 +0900 From: Sergey Senozhatsky To: Qian Cai Cc: tytso@mit.edu, Arnd Bergmann , gregkh@linuxfoundation.org, sergey.senozhatsky.work@gmail.com, pmladek@suse.com, rostedt@goodmis.org, Catalin Marinas , will@kernel.org, dan.j.williams@intel.com, peterz@infradead.org, longman@redhat.com, tglx@linutronix.de, linux-mm@kvack.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] char/random: silence a lockdep splat with printk() Message-ID: <20191205010055.GO93017@google.com> References: <1573679785-21068-1-git-send-email-cai@lca.pw> <637027D4-BBDD-4AA6-B03C-556060988957@lca.pw> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <637027D4-BBDD-4AA6-B03C-556060988957@lca.pw> 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 Hi, On (19/12/03 13:46), Qian Cai wrote: > > On Nov 13, 2019, at 4:16 PM, Qian Cai wrote: > > > > From: Sergey Senozhatsky > > > > Sergey didn't like the locking order, > > > > uart_port->lock -> tty_port->lock > > > > uart_write (uart_port->lock) > > __uart_start > > pl011_start_tx > > pl011_tx_chars > > uart_write_wakeup > > tty_port_tty_wakeup > > tty_port_default > > tty_port_tty_get (tty_port->lock) > > > > but those code is so old, and I have no clue how to de-couple it after > > checking other locks in the splat. There is an onging effort to make all > > printk() as deferred, so until that happens, workaround it for now as a > > short-term fix. > > Sergey, could we have a ACK from you so Ted might be able to merge? Not sure if I can ACK it, but overall it makes sense to use deferred printk there. [..] > > > [cai@lca.pw: add a commit log.] > > Signed-off-by: Sergey Senozhatsky > > Signed-off-by: Qian Cai > > --- > > > > Sergey, please let us know if you are fine with the Signed-off-by. A 'Reviewed-by' will suffice. Reviewed-by: Sergey Senozhatsky -ss