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=-2.1 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,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 238D6C43144 for ; Fri, 29 Jun 2018 01:47:13 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 0BA4F27A47 for ; Fri, 29 Jun 2018 01:47:11 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="BhWLy7t6" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 0BA4F27A47 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=gmail.com 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 S936436AbeF2BrJ (ORCPT ); Thu, 28 Jun 2018 21:47:09 -0400 Received: from mail-pl0-f66.google.com ([209.85.160.66]:40807 "EHLO mail-pl0-f66.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S934863AbeF2BrI (ORCPT ); Thu, 28 Jun 2018 21:47:08 -0400 Received: by mail-pl0-f66.google.com with SMTP id t6-v6so3640652plo.7; Thu, 28 Jun 2018 18:47:07 -0700 (PDT) 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=/cvEQWDU2WRceqEFixjxn/m1I2LIbLzT7WMkguwJooY=; b=BhWLy7t6GZzOreb7m7rprv6egyxSmCA2MqYQ0fNPcrdDfeoSay9QN2Xcu/XNzlnToL ovVm1Ltsh8hmF9cI2jYFAx6pZZZBstTNOo0MvcSPDhKt/yC+AIZJ4pWXX31qzy8nXFHs 5/xb1+hdSpMDWpQe7uMmqISwYs2S6/Fet6i64RamZCg1dzOVENScxkW1DtyEf/mNx5We TRFu14wZkq/+ZW3Lk9qbllujqbVVulvNnLF2cmtxoEZeu61bSrSJbtXUC9mni7OPhEHn nC3SBhVY3EBCb1QtgNR1546IJzXmpy4f1c8mRlSDotExDTwphSHkld7J3wH+5kVFFxHW J7cA== 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=/cvEQWDU2WRceqEFixjxn/m1I2LIbLzT7WMkguwJooY=; b=BB1OgXgnW/AHPGaApb8jXm4SXEDfxtOQ/USVa+Z7D88aEqf5csRQDWDcKowrGlPLhv 25Adwk/kUZnQh0SDjKI3PFYZuw0Y/mdfPjmtglQYknAJNLtamV2phCgMP6NTgIxdAq/Y ElmFdz3sNnFozyoYiLpOS6/FGAgeh/G9d5IJMtrbYJuPBFhEejKGkDJuQ6Cl4d4Af2Gy 1BKxLFhrjLBP9C6ho2/jUxnQDDTSrMa8qVHibH9Mq5q+g9mpaCa8HpEa+gpRBLjO0hrg SDM3Ub4pudfKyA8SVlqtLxy/Xey/0TDDYahFHvmGoWZCbdo3nYjvuVhITrJRmanY98aj BOMw== X-Gm-Message-State: APt69E1FJQszBBxGdoT28junBtGkD+70F2qQBAe8esWn8NLY4TGZ2g01 660c66b4I1XEHxW8dM56gCM= X-Google-Smtp-Source: ADUXVKINu4ertEKSFV5HaE2bCtKwTyv3QDqOJbUwlap5Sc0wOBWyJQ8wQ/Jtenum9ckwlnPlNnFW4g== X-Received: by 2002:a17:902:904c:: with SMTP id w12-v6mr12699365plz.34.1530236827575; Thu, 28 Jun 2018 18:47:07 -0700 (PDT) Received: from localhost ([110.70.26.165]) by smtp.gmail.com with ESMTPSA id p2-v6sm10740563pgq.14.2018.06.28.18.47.05 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Thu, 28 Jun 2018 18:47:06 -0700 (PDT) Date: Fri, 29 Jun 2018 10:47:03 +0900 From: Sergey Senozhatsky To: Petr Mladek , Steven Rostedt Cc: Sergey Senozhatsky , Sergey Senozhatsky , Peter Zijlstra , Tetsuo Handa , linux-kernel@vger.kernel.org, stable@vger.kernel.org Subject: Re: [PATCH v2 3/3] printk/nmi: Prevent deadlock when accessing the main log buffer in NMI Message-ID: <20180629014703.GA614@jagdpanzerIV> References: <20180627140817.27764-1-pmladek@suse.com> <20180627142028.11259-1-pmladek@suse.com> <20180628022507.GD481@jagdpanzerIV> <20180628094125.cq5qunckjyxhbovb@pathway.suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180628094125.cq5qunckjyxhbovb@pathway.suse.cz> User-Agent: Mutt/1.10.0 (2018-05-17) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On (06/28/18 11:41), Petr Mladek wrote: > > > > A side note: This nesting also handles recursive printk-s for us. > > > > NMI: > > printk_nmi_enter > > ftrace_dump > > printk_nmi_direct_enter > > vprintk_func > > spin_lock(logbuf_lock) > > vprintk_store > > vsprintf > > WARN_ON > > vprintk_func > > vprintk_nmi > > Uff, it seems that the current design is "good" at lest from some > points of view. yep yep > > > + len = vprintk_store(0, LOGLEVEL_DEFAULT, NULL, 0, fmt, args); > > > + raw_spin_unlock(&logbuf_lock); > > > + defer_console(); > > > + return len; > > > + } > > > > So, maybe, something a bit better than defer_console(). > > I am not super happy with the name either. But wakeup_console(), > schedule_console(), or queue_console() looked confusing. Hmm. defer_console() makes me think that we are dealing with that fbcon=nodefer and deferred console takeover thing here. So I summon Mr. Rostedt! Does schedule_console_output() look bad? What about defer_console_output()? Any other ideas? -ss