From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from smtp.codeaurora.org by pdx-caf-mail.web.codeaurora.org (Dovecot) with LMTP id 7AT+JzVVGFszcwAAmS7hNA ; Wed, 06 Jun 2018 21:42:17 +0000 Received: by smtp.codeaurora.org (Postfix, from userid 1000) id 44EA5607F7; Wed, 6 Jun 2018 21:42:17 +0000 (UTC) Authentication-Results: smtp.codeaurora.org; dkim=pass (2048-bit key) header.d=tycho-ws.20150623.gappssmtp.com header.i=@tycho-ws.20150623.gappssmtp.com header.b="LAl54Jcd" X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on pdx-caf-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.9 required=2.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,MAILING_LIST_MULTI,T_DKIMWL_WL_MED autolearn=ham autolearn_force=no version=3.4.0 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by smtp.codeaurora.org (Postfix) with ESMTP id 9880A601C3; Wed, 6 Jun 2018 21:42:16 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 smtp.codeaurora.org 9880A601C3 Authentication-Results: pdx-caf-mail.web.codeaurora.org; dmarc=none (p=none dis=none) header.from=tycho.ws Authentication-Results: pdx-caf-mail.web.codeaurora.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752362AbeFFVmN (ORCPT + 25 others); Wed, 6 Jun 2018 17:42:13 -0400 Received: from mail-pf0-f196.google.com ([209.85.192.196]:35409 "EHLO mail-pf0-f196.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752093AbeFFVmJ (ORCPT ); Wed, 6 Jun 2018 17:42:09 -0400 Received: by mail-pf0-f196.google.com with SMTP id c22-v6so3361135pfi.2 for ; Wed, 06 Jun 2018 14:42:09 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=tycho-ws.20150623.gappssmtp.com; s=20150623; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to:user-agent; bh=VJ8qk5s+xYKiHwGZWZI+ZIC9IXGEnt0+TzQXBlrrZ/s=; b=LAl54JcdFOjO/D1mRSPxEJpDzhAD9uECkT7NgIE+1Vua4tH+ePaj0aQ8mio+mV0RP8 EMhsjWOStmhJewnCz1kHksHkpKNjh6LF3kYsBQra3c5HDJ0IdW0RT9SaU/p+Bp6LuxRu gh9i7KlyKTJE6L80bV/kaU3kXKLQqJpMY7jK53NUNd+nnPmHygmN8hFZyS3RZkKp5xvr VgWDdOP6qqrwAOBWse1WLdKgsm1kNHiLMhyy7+fdoZaX2wHYY0fvu0I3rV2gbQse0Pdi 7OmR2MKM7A3hR/uyTF6RIX/hRuOFeykRd+G5iKjwRaXzJ/5YTRpG7Mb7m1cCH8PaiEPN y/tQ== 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=VJ8qk5s+xYKiHwGZWZI+ZIC9IXGEnt0+TzQXBlrrZ/s=; b=j8DMC+2dnvwVpgWg9P7a9VRW4bNpJH3GsPm7MNMTkgTdEuUWMhwp/Qi7btyqa/Ax6L ZMX6YrZWyBAqbxn5rzfnqbZ8fnOU3pD9rEH9YDXOMAerlPPAebP9R3m4LNP8EUHPwNk8 q+0Dlu9RVrk0tYboqY7KBhDu6lopFti/zvlKOXAbXdIq4fWNoUsN8z40NLjs53spkThm 4m3nFKpS+yXylAK89EVdDdm3ttt2SElCgqeBI6lXn0DofxrsuutG9bZv6bR/OF7T4mVR 35lekVE8iRv9hGkS5GtQ3hGj2PYJ6VbEce0pjYjxpAcVf4rtrsNTrRI8IDGfIUuXFPOA +lNw== X-Gm-Message-State: APt69E30VJDKb0CVgh6HC5yUyYzymsoZX4JU1xnChFoPiLCSOqMu2ixZ 0HU6T5fuEA4fBCbE1nC2BBkqTlK3 X-Google-Smtp-Source: ADUXVKKvoj9EdlIbK3eAIOqOr5P0MAxx/BzvkkYvM/XzDyeayWTLOA2snlvRvNy2VcTekhVj9kGghw== X-Received: by 2002:a63:78c6:: with SMTP id t189-v6mr3908826pgc.239.1528321329076; Wed, 06 Jun 2018 14:42:09 -0700 (PDT) Received: from cisco ([128.107.241.182]) by smtp.gmail.com with ESMTPSA id y2-v6sm1505367pfk.82.2018.06.06.14.42.07 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Wed, 06 Jun 2018 14:42:07 -0700 (PDT) Date: Wed, 6 Jun 2018 15:42:07 -0600 From: Tycho Andersen To: "Serge E. Hallyn" Cc: Greg Kroah-Hartman , Jiri Slaby , linux-serial@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] uart: fix race between uart_put_char() and uart_shutdown() Message-ID: <20180606214207.GB9999@cisco> References: <20180605000127.5495-1-tycho@tycho.ws> <20180605035936.GA19642@mail.hallyn.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180605035936.GA19642@mail.hallyn.com> User-Agent: Mutt/1.9.4 (2018-02-28) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Jun 04, 2018 at 10:59:36PM -0500, Serge E. Hallyn wrote: > Quoting Tycho Andersen (tycho@tycho.ws): > > Unfortunately, I don't have any insightful thoughts about how to test this. > > Ideas are appreciated :) > > I wonder whether there is something we can do with qemu -serial pipe: ? Good idea. I couldn't get tty_put_char() to trigger nicely, but I just hard coded one to occur, so at least now I know that this doesn't deadlock when called normally. Another suggestion Serge gave off list was to write a kernel module that implemented a driver. I'll see about doing that to see if I can force the original crash. > > Signed-off-by: Tycho Andersen > > Acked-by: Serge Hallyn Thanks! Tycho