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 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 smtp.lore.kernel.org (Postfix) with ESMTPS id 8B8A8C00140 for ; Mon, 8 Aug 2022 13:14:07 +0000 (UTC) Received: from localhost ([::1]:53116 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1oL2a6-0000qC-Hz for qemu-devel@archiver.kernel.org; Mon, 08 Aug 2022 09:14:06 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:56098) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1oL2Xu-0007Hs-GF for qemu-devel@nongnu.org; Mon, 08 Aug 2022 09:11:53 -0400 Received: from kylie.crudebyte.com ([5.189.157.229]:53371) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1oL2Xm-0004bB-VF for qemu-devel@nongnu.org; Mon, 08 Aug 2022 09:11:48 -0400 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=crudebyte.com; s=kylie; h=Content-Type:Content-Transfer-Encoding: MIME-Version:References:In-Reply-To:Message-ID:Date:Subject:Cc:To:From: Content-ID:Content-Description; bh=w07c9SuUHA+2QDB70ppoZYZfffO6AOQro0sNbnhqUCQ=; b=efZNDAJVDx1RL4pB+4Gf5RQ9Cm P3WnrS+8GTpkk4A0eJ3PoLboXibr0TiJ2O6368gXGnWjXSyafyXxN1M1Gsm80LSK/gSIl3wMjNeTg D0BF9sF64U+IyQW9bhH+K30JuWLvz0VdwwlXtrQW5o1LcJuEAMUxzwB9u/hxpxRsVjATF3xh++CbT Wb61227ro+fLVSJFjwTzkhRPswA2Ib+Es4/xLjPSHcH6RW462YmGD9G87/Hasm9iJqps+kPILjilh 6dAzj0fy9+MjxSBhplxm78XVjAy/6r2OgX+X3EwkZVwS+h0biHydwb7mx9Vu7L2G2qfWr9ME3jONz CbdtpcM+BMtOjFC9cQkWKxxmIiePKEVpHGdvivKhhOC+wv84vBR0C5CYrAdayYArfpDXiTg1YtmEg n6XHa7xDNi8NJnDhW7Wi6b2+y/OEDZByJFqtSR2JlyFoLmYUJTZOjPehsZhlwlfvczyK9tSI1PUb+ 0EDHy2h+tF6tp5JY9h4K4Fpfs57lZhkv03OXE61+EKG8LOx6+1WMcj039ZnoK6BDlKkbve3cwQ1jq rpTNaFUpEacLCUFrmO1v2EpGNrT+BzzL8GGfQQoWVSygov1zuu7AvaK/OrVGXf1jP6HeUGRbFYlF6 YEFVBHTEgSfswLzm2JAE1X78VVewq+1QFVtAmX3NY=; From: Christian Schoenebeck To: qemu-devel@nongnu.org Cc: Nikita Ivanov , Peter Maydell , =?ISO-8859-1?Q?Marc=2DAndr=E9?= Lureau , Greg Kurz , Jason Wang , Michael Roth , Konstantin Kostiuk , Paolo Bonzini , Markus Armbruster Subject: Re: [PATCH] error handling: Use TFR() macro where applicable Date: Mon, 08 Aug 2022 15:11:35 +0200 Message-ID: <7218690.D19hzYb2mh@silver> In-Reply-To: <3206015.kY3CcG7ZbH@silver> References: <877d3jupln.fsf@pond.sub.org> <3206015.kY3CcG7ZbH@silver> MIME-Version: 1.0 Content-Transfer-Encoding: 7Bit Content-Type: text/plain; charset="us-ascii" Received-SPF: pass client-ip=5.189.157.229; envelope-from=qemu_oss@crudebyte.com; helo=kylie.crudebyte.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 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, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-0.01 autolearn=ham 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: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Montag, 8. August 2022 14:52:28 CEST Christian Schoenebeck wrote: > On Montag, 8. August 2022 10:05:56 CEST Markus Armbruster wrote: > > Nikita Ivanov writes: > > > Summing up the discussion above, I suggest the following patch for TFR() > > > macro refactoring. (The patch is sequential to the first one I > > > introduced > > > in the start of the discussion). > > > > > >>From 6318bee052900aa93bba6620b53c7cb2290e5001 Mon Sep 17 00:00:00 2001 > > >> > > > From: Nikita Ivanov > > > Date: Mon, 8 Aug 2022 09:30:34 +0300 > > > Subject: [PATCH] Refactoring: rename TFR() to TEMP_FAILURE_RETRY() > > > > > > glibc's unistd.h header provides the same macro with the > > > subtle difference in type casting. Adjust macro name to the > > > common standard and define conditionally. > > > > > > Signed-off-by: Nikita Ivanov > > > --- > > > > > > chardev/char-fd.c | 2 +- > > > chardev/char-pipe.c | 12 +++++++++--- > > > hw/9pfs/9p-local.c | 6 ++++-- > > > include/qemu/osdep.h | 6 ++++-- > > > net/l2tpv3.c | 8 +++++--- > > > net/tap-linux.c | 2 +- > > > net/tap.c | 10 ++++++---- > > > os-posix.c | 2 +- > > > qga/commands-posix.c | 2 +- > > > tests/qtest/libqtest.c | 2 +- > > > util/main-loop.c | 2 +- > > > util/osdep.c | 2 +- > > > 12 files changed, 35 insertions(+), 21 deletions(-) > > > > > > diff --git a/chardev/char-fd.c b/chardev/char-fd.c > > > index cf78454841..7f5ed9aba3 100644 > > > --- a/chardev/char-fd.c > > > +++ b/chardev/char-fd.c > > > @@ -198,7 +198,7 @@ int qmp_chardev_open_file_source(char *src, int > > > flags, > > > Error **errp) > > > > > > { > > > > > > int fd = -1; > > > > > > - TFR(fd = qemu_open_old(src, flags, 0666)); > > > + TEMP_FAILURE_RETRY(fd = qemu_open_old(src, flags, 0666)); > > > > > > if (fd == -1) { > > > > > > error_setg_file_open(errp, errno, src); > > > > > > } > > > > > > diff --git a/chardev/char-pipe.c b/chardev/char-pipe.c > > > index 66d3b85091..aed97e306b 100644 > > > --- a/chardev/char-pipe.c > > > +++ b/chardev/char-pipe.c > > > @@ -131,8 +131,12 @@ static void qemu_chr_open_pipe(Chardev *chr, > > > > > > filename_in = g_strdup_printf("%s.in", filename); > > > filename_out = g_strdup_printf("%s.out", filename); > > > > > > - TFR(fd_in = qemu_open_old(filename_in, O_RDWR | O_BINARY)); > > > - TFR(fd_out = qemu_open_old(filename_out, O_RDWR | O_BINARY)); > > > + TEMP_FAILURE_RETRY( > > > + fd_in = qemu_open_old(filename_in, O_RDWR | O_BINARY) > > > + ); > > > + TEMP_FAILURE_RETRY( > > > + fd_out = qemu_open_old(filename_out, O_RDWR | O_BINARY) > > > + ); > > > > Style question: do we want the ");" on its own line? I think we > > generally don't do that for function and function-like macro calls. > > So far scripts/checkpatch.pl doesn't complain, therefore I used this code > style in QEMU before. > > BTW, another exotic function call code style (not being compalained about > yet) in approach: > https://lore.kernel.org/qemu-devel/E1oDQqv-0003d4-Hm@lizzy.crudebyte.com/ > > > > g_free(filename_in); > > > g_free(filename_out); > > > if (fd_in < 0 || fd_out < 0) { > > > > > > @@ -142,7 +146,9 @@ static void qemu_chr_open_pipe(Chardev *chr, > > > > > > if (fd_out >= 0) { > > > > > > close(fd_out); > > > > > > } > > > > > > - TFR(fd_in = fd_out = qemu_open_old(filename, O_RDWR | > > > O_BINARY)); > > > + TEMP_FAILURE_RETRY( > > > + fd_in = fd_out = qemu_open_old(filename, O_RDWR | O_BINARY) > > > + ); > > > > > > if (fd_in < 0) { > > > > > > error_setg_file_open(errp, errno, filename); > > > return; > > > > > > diff --git a/hw/9pfs/9p-local.c b/hw/9pfs/9p-local.c > > > index c90ab947ba..e803c05d0c 100644 > > > --- a/hw/9pfs/9p-local.c > > > +++ b/hw/9pfs/9p-local.c > > > @@ -470,7 +470,7 @@ static ssize_t local_readlink(FsContext *fs_ctx, > > > V9fsPath *fs_path, > > > > > > if (fd == -1) { > > > > > > return -1; > > > > > > } > > > > > > - TFR(tsize = read(fd, (void *)buf, bufsz)); > > > + TEMP_FAILURE_RETRY(tsize = read(fd, (void *)buf, bufsz)); > > > > > > close_preserve_errno(fd); > > > > > > } else if ((fs_ctx->export_flags & V9FS_SM_PASSTHROUGH) || > > > > > > (fs_ctx->export_flags & V9FS_SM_NONE)) { > > > > > > @@ -906,7 +906,9 @@ static int local_symlink(FsContext *fs_ctx, const > > > char > > > *oldpath, > > > > > > } > > > /* Write the oldpath (target) to the file. */ > > > oldpath_size = strlen(oldpath); > > > > > > - TFR(write_size = write(fd, (void *)oldpath, oldpath_size)); > > > + TEMP_FAILURE_RETRY( > > > + write_size = write(fd, (void *)oldpath, oldpath_size) > > > + ); > > > > > > close_preserve_errno(fd); > > > > > > if (write_size != oldpath_size) { > > > > > > diff --git a/include/qemu/osdep.h b/include/qemu/osdep.h > > > index b1c161c035..55f2927d8b 100644 > > > --- a/include/qemu/osdep.h > > > +++ b/include/qemu/osdep.h > > > @@ -242,8 +242,10 @@ void QEMU_ERROR("code path is reachable") > > > > > > #if !defined(ESHUTDOWN) > > > #define ESHUTDOWN 4099 > > > #endif > > > > > > - > > > -#define TFR(expr) do { if ((expr) != -1) break; } while (errno == > > > EINTR) > > > +#if !defined(TEMP_FAILURE_RETRY) > > > +#define TEMP_FAILURE_RETRY(expr) \ > > > + do { if ((expr) != -1) break; } while (errno == EINTR) > > > +#endif > > > > GLibc's version is > > > > # define TEMP_FAILURE_RETRY(expression) \ > > > > (__extension__ > > \ > > > ({ long int __result; > > \ > > > do __result = (long int) (expression); > > \ > > > while (__result == -1L && errno == EINTR); > > \ > > > __result; })) > > > > The difference isn't just "type casting", it's also statement > > vs. expression. > > > > Is it a good idea to have the macro expand into a statement on some > > hosts, and into an expression on others? Sure, CI should catch any uses > > as expression, but delaying compile errors to CI wastes developer time. > > For consistency and simplicity, I would define exactly one version (no > ifdefs) of the macro with a different macro name than glibc's > TEMP_FAILURE_RETRY(), and use that QEMU specific macro name in QEMU code > everywhere. > > As for statement vs. expression: The only advantage of the statement version > is if you'd need __result as an rvalue, which is not needed ATM, right? So > I would go for the expression version (with cast) for now. > > The glibc history does not reveal why they chose the statement version. > > Best regards, > Christian Schoenebeck Sorry: s/rvalue/lvalue/ i.e. if you need the memory address of result or if you need to take the result value of the last iteration in 'expression' into account.