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 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id EF955C433EF for ; Fri, 12 Nov 2021 08:36:15 +0000 (UTC) Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 80BEE60F41 for ; Fri, 12 Nov 2021 08:36:15 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org 80BEE60F41 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=gmail.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=nongnu.org Received: from localhost ([::1]:48724 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1mlS2g-0008Lo-Hn for qemu-devel@archiver.kernel.org; Fri, 12 Nov 2021 03:36:14 -0500 Received: from eggs.gnu.org ([209.51.188.92]:34812) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1mlS0p-0005Ll-FB; Fri, 12 Nov 2021 03:34:19 -0500 Received: from [2a00:1450:4864:20::333] (port=40703 helo=mail-wm1-x333.google.com) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.90_1) (envelope-from ) id 1mlS0n-0003Oa-Tv; Fri, 12 Nov 2021 03:34:19 -0500 Received: by mail-wm1-x333.google.com with SMTP id az33-20020a05600c602100b00333472fef04so8507564wmb.5; Fri, 12 Nov 2021 00:34:17 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=kbcCaDblm/o93W5Pe7Y7frx6YvthUznZiClzVudIK44=; b=mopJ3rqkIVAbOi+UlNSUw+L5r4Oyw44HcV5qjpn7LkCFKqwdQKktRwUYU68yVoRTAy fEJ0F6L6TSVvWU0+nbZG8e+lDO2zTNl5udmvgnp8oxeQN6HFMwPct+mRbzAidZy6CpeM Ciwm+gHjaM/G082gy+zkIVwEpIZNBtMZkDJ8w+ULnbjtvFymGSnZh1SBiUZ77CVQpQbD OvhiS2D21+xYDOjQvcucFWpI/ouLEXg0/MFWlg3ihtb1UwnBy7kXJqtGkk4CparMNEei V2UxAdU/LkRgcnU+ughz/j1H5B7yGNkd0jI0XmPJCWD6FkSyleX52t5EN+J0FK/DkNoI Rhnw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=kbcCaDblm/o93W5Pe7Y7frx6YvthUznZiClzVudIK44=; b=KHw6bBb5fLzHDPk/ysXVhJKFvTTWRncU4P3Dx188uQAGEF/EbA1tEnmg6uqx1UnAEV WRTZeXDPPBUr6BD9AlM8ufVjhjxZXjB8lVp0y+k6aKBRWWZmM0lSeblAScOj35/M3H38 /+AZsRVYg9BCkLKoByJ2If/tZzRt+LD7oSQ2ykAMfc/1DeRK4twEYmWCbDHIkJDGnPIk KY/ey5gF97xgyDwQLQEKlKARBdf6ftKoW5P2dq7G0vIEw/wponrfyYJmfGXl2VboTP1k umnuB6Nk36ID3x99YLjBohA1vmKPmnRgtSuRBmPQcMAMIkk0WNAQm65cyPUKJMA3/1uu cCsQ== X-Gm-Message-State: AOAM5310pP0j+W3ityY/nMjr39FUeraHIhfl8GcRTXvmQUfqVtxVbgdW I3nxBxxOwpvkTN7sZ7cprNTXJKbtdFPiWBIzH9GAFMKS X-Google-Smtp-Source: ABdhPJx25zNL6/PqhB3khhWBjBRK3a8soLsByP2WOgiABfKqEVfXTroPLxWEp0stiTTjuXwWzF0PE7LV5kk9m3OovAI= X-Received: by 2002:a1c:4e04:: with SMTP id g4mr31556007wmh.15.1636705634025; Fri, 12 Nov 2021 00:27:14 -0800 (PST) MIME-Version: 1.0 References: <20211111153354.18807-1-rvkagan@yandex-team.ru> <20211111153354.18807-3-rvkagan@yandex-team.ru> In-Reply-To: <20211111153354.18807-3-rvkagan@yandex-team.ru> From: =?UTF-8?B?TWFyYy1BbmRyw6kgTHVyZWF1?= Date: Fri, 12 Nov 2021 12:27:02 +0400 Message-ID: Subject: Re: [PATCH 02/10] chardev/char-socket: tcp_chr_recv: don't clobber errno To: Roman Kagan Content-Type: multipart/alternative; boundary="000000000000eb051b05d0933999" X-Host-Lookup-Failed: Reverse DNS lookup failed for 2a00:1450:4864:20::333 (failed) Received-SPF: pass client-ip=2a00:1450:4864:20::333; envelope-from=marcandre.lureau@gmail.com; helo=mail-wm1-x333.google.com X-Spam_score_int: -12 X-Spam_score: -1.3 X-Spam_bar: - X-Spam_report: (-1.3 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, FREEMAIL_FROM=0.001, HTML_MESSAGE=0.001, PDS_HP_HELO_NORDNS=0.001, RCVD_IN_DNSWL_NONE=-0.0001, RDNS_NONE=0.793, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=no autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Kevin Wolf , "open list:Block layer core" , "Michael S. Tsirkin" , QEMU , Raphael Norwitz , Hanna Reitz , yc-core@yandex-team.ru, Paolo Bonzini Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" --000000000000eb051b05d0933999 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable On Thu, Nov 11, 2021 at 7:38 PM Roman Kagan wrote: > tcp_chr_recv communicates the specific error condition to the caller via > errno. However, after setting it, it may call into some system calls or > library functions which can clobber the errno. > > Avoid this by moving the errno assignment to the end of the function. > > Signed-off-by: Roman Kagan > Reviewed-by: Marc-Andr=C3=A9 Lureau --- > chardev/char-socket.c | 14 +++++++------- > 1 file changed, 7 insertions(+), 7 deletions(-) > > diff --git a/chardev/char-socket.c b/chardev/char-socket.c > index 836cfa0bc2..90054ce58c 100644 > --- a/chardev/char-socket.c > +++ b/chardev/char-socket.c > @@ -346,13 +346,6 @@ static ssize_t tcp_chr_recv(Chardev *chr, char *buf, > size_t len) > NULL); > } > > - if (ret =3D=3D QIO_CHANNEL_ERR_BLOCK) { > - errno =3D EAGAIN; > - ret =3D -1; > - } else if (ret =3D=3D -1) { > - errno =3D EIO; > - } > - > if (msgfds_num) { > /* close and clean read_msgfds */ > for (i =3D 0; i < s->read_msgfds_num; i++) { > @@ -381,6 +374,13 @@ static ssize_t tcp_chr_recv(Chardev *chr, char *buf, > size_t len) > #endif > } > > + if (ret =3D=3D QIO_CHANNEL_ERR_BLOCK) { > + errno =3D EAGAIN; > + ret =3D -1; > + } else if (ret =3D=3D -1) { > + errno =3D EIO; > + } > + > return ret; > } > > -- > 2.33.1 > > > --=20 Marc-Andr=C3=A9 Lureau --000000000000eb051b05d0933999 Content-Type: text/html; charset="UTF-8" Content-Transfer-Encoding: quoted-printable


=
On Thu, Nov 11, 2021 at 7:38 PM Roman= Kagan <rvkagan@yandex-team.ru= > wrote:
= tcp_chr_recv communicates the specific error condition to the caller via errno.=C2=A0 However, after setting it, it may call into some system calls = or
library functions which can clobber the errno.

Avoid this by moving the errno assignment to the end of the function.

Signed-off-by: Roman Kagan <rvkagan@yandex-team.ru>

Reviewed-by: Marc-Andr=C3=A9 Lureau <marcandre.lureau@redhat.com>

---
=C2=A0chardev/char-socket.c | 14 +++++++-------
=C2=A01 file changed, 7 insertions(+), 7 deletions(-)

diff --git a/chardev/char-socket.c b/chardev/char-socket.c
index 836cfa0bc2..90054ce58c 100644
--- a/chardev/char-socket.c
+++ b/chardev/char-socket.c
@@ -346,13 +346,6 @@ static ssize_t tcp_chr_recv(Chardev *chr, char *buf, s= ize_t len)
=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2= =A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 NULL);
=C2=A0 =C2=A0 =C2=A0}

-=C2=A0 =C2=A0 if (ret =3D=3D QIO_CHANNEL_ERR_BLOCK) {
-=C2=A0 =C2=A0 =C2=A0 =C2=A0 errno =3D EAGAIN;
-=C2=A0 =C2=A0 =C2=A0 =C2=A0 ret =3D -1;
-=C2=A0 =C2=A0 } else if (ret =3D=3D -1) {
-=C2=A0 =C2=A0 =C2=A0 =C2=A0 errno =3D EIO;
-=C2=A0 =C2=A0 }
-
=C2=A0 =C2=A0 =C2=A0if (msgfds_num) {
=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0/* close and clean read_msgfds */
=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0for (i =3D 0; i < s->read_msgfds_nu= m; i++) {
@@ -381,6 +374,13 @@ static ssize_t tcp_chr_recv(Chardev *chr, char *buf, s= ize_t len)
=C2=A0#endif
=C2=A0 =C2=A0 =C2=A0}

+=C2=A0 =C2=A0 if (ret =3D=3D QIO_CHANNEL_ERR_BLOCK) {
+=C2=A0 =C2=A0 =C2=A0 =C2=A0 errno =3D EAGAIN;
+=C2=A0 =C2=A0 =C2=A0 =C2=A0 ret =3D -1;
+=C2=A0 =C2=A0 } else if (ret =3D=3D -1) {
+=C2=A0 =C2=A0 =C2=A0 =C2=A0 errno =3D EIO;
+=C2=A0 =C2=A0 }
+
=C2=A0 =C2=A0 =C2=A0return ret;
=C2=A0}

--
2.33.1




--
Marc-Andr=C3=A9 Lureau
--000000000000eb051b05d0933999--