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=-4.1 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SPF_PASS,URIBL_BLOCKED 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 00A5AC43441 for ; Thu, 15 Nov 2018 19:34:38 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id BD9892086C for ; Thu, 15 Nov 2018 19:34:37 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=augury.com header.i=@augury.com header.b="ZZ7jmudz" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org BD9892086C Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=augury.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-bluetooth-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1725868AbeKPFnn (ORCPT ); Fri, 16 Nov 2018 00:43:43 -0500 Received: from mail-vk1-f195.google.com ([209.85.221.195]:40707 "EHLO mail-vk1-f195.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725841AbeKPFnn (ORCPT ); Fri, 16 Nov 2018 00:43:43 -0500 Received: by mail-vk1-f195.google.com with SMTP id v70so4734552vkv.7 for ; Thu, 15 Nov 2018 11:34:35 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=augury.com; s=google; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=/PcPtBvYIOe7vbjJxmgEzQ3mqAOb1zB7gDm2IAIuvSw=; b=ZZ7jmudzG5V/HLhx7NPI0yJlZuEGVmW+HtZWrtO4ZpEJkbFjqciDkbmGsvXETimY96 qJD7SOP5fdMS4RlITQvuEwUIKQlHJa7A7ZTh/WsAO2cmGTScUPuOd0UpHTcEaFFCAqFb 0DSfgm8SpAFGGB+Mh8UaYtsI2Ft1M62OgHpCA= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=/PcPtBvYIOe7vbjJxmgEzQ3mqAOb1zB7gDm2IAIuvSw=; b=NKnDpdP7itKWnr1lj+G74NqB0z45JhRd2viminh6B6s0iSc2ZkcgzBhGasnOf0C/H+ im++nisFqbA5xEjGpHE1+ZQc+7+IrIB27A5jCXmxSSlaESx77dj6O/GEuyRe/Bzs2vUu 2lp+Uutw7h0/uaCCBtA5EvQ+73ZVDhG9hfyayQ4coFvbIuI1Nwi7kPJXrdsheCJfaEhU YGZD0BK/LYJgt5Rpqh3pygMMRNZi9++WDo/7tD/XoHyRPpe5zcmNIF7PX9Myzonn9hQn zhfIjjbaTb2MRDzbEbNVIto1NNgexdlYG8Vvkd5XnBW2EU1WQETfquECsI4t9PaDxwYY r1Hw== X-Gm-Message-State: AGRZ1gJJBzSsnEnbSp/OkZeyK2Q/Abw7gUnsjL+RAzpAmyP/wp9/2N8B vjc/nEUVA2FI/qGVIVVgj7W1MPO8ZK7TuuOtGK6S5A== X-Google-Smtp-Source: AJdET5cmhmiINKB5k34NN54uc9pP2yXCr2vsB/3JTNmOaEVlY/8kqc1LkmEFMauUSlgrmLvjqr/+0aQ96hTciudiLSU= X-Received: by 2002:a1f:83ca:: with SMTP id f193mr3162238vkd.75.1542310474896; Thu, 15 Nov 2018 11:34:34 -0800 (PST) MIME-Version: 1.0 References: <20181115115324.10215-1-gbenhaim@augury.com> In-Reply-To: From: Gal Ben Haim Date: Thu, 15 Nov 2018 21:34:23 +0200 Message-ID: Subject: Re: [PATCH BlueZ] shared/io-mainloop: Try to write to the pipe only if there are readers To: Luiz Augusto von Dentz Cc: linux-bluetooth@vger.kernel.org Content-Type: text/plain; charset="UTF-8" Sender: linux-bluetooth-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-bluetooth@vger.kernel.org doesn't my first patch of ignoring SIGPIPE simplify this? errno of the write op will be EPIPE.. I can move it to main.c On Thu, Nov 15, 2018 at 2:38 PM Luiz Augusto von Dentz wrote: > > Hi Gal, > On Thu, Nov 15, 2018 at 1:55 PM Gal Ben-Haim wrote: > > > > bluetoothd receives a SIGPIPE and terminates if writing to a pipe that > > was acquired by AcquireNotify and there are no readers. it can be > > reproduced by terminating the reader process without closing the reader > > end of the pipe. > > > > poll is used to check for a POLLRDHUP event before write and an EPIPE > > error is returned if the peer closed its end of the pipe. > > --- > > src/shared/io-mainloop.c | 8 ++++++++ > > 1 file changed, 8 insertions(+) > > > > diff --git a/src/shared/io-mainloop.c b/src/shared/io-mainloop.c > > index 2306c3479..4a70449fc 100644 > > --- a/src/shared/io-mainloop.c > > +++ b/src/shared/io-mainloop.c > > @@ -27,6 +27,7 @@ > > > > #include > > #include > > +#include > > #include > > > > #include "src/shared/mainloop.h" > > @@ -305,7 +306,14 @@ ssize_t io_send(struct io *io, const struct iovec *iov, int iovcnt) > > if (!io || io->fd < 0) > > return -ENOTCONN; > > > > + struct pollfd fds[1]; > > + fds[0].fd = io->fd; > > + fds[0].events = POLLRDHUP; > > do { > > + if (poll(fds, 1, 0) > 0 && fds[0].revents & POLLRDHUP > 0) { > > + return -EPIPE; > > + } > > + > > ret = writev(io->fd, iov, iovcnt); > > } while (ret < 0 && errno == EINTR); > > > > -- > > 2.19.1 > > We normally do it a bit differently, we setup a write handler using > io_set_write_handler which informs when the fd is writable, otherwise > we maybe polling twice here since the user of the io may already be > using that mechanism. That said you are actually checking for HUP > which is something done io_set_disconnect_handler, which is already in > use. I suspect to really get this done cleanly we should perhaps use > MSG_NOSIGNAL when trying to write. > > -- > Luiz Augusto von Dentz