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 bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (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 0068DC3600C for ; Tue, 8 Apr 2025 04:30:19 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:Content-Transfer-Encoding: Content-Type:In-Reply-To:From:References:Cc:To:Subject:MIME-Version:Date: Message-ID:Reply-To:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=FVk1eTGXVWxw3i4OEda44NwW29chjqvlqWUvewaxbH8=; b=QsPfgUusFF0eSWSt+LZhkblf0t kdvfj5U5hRAC7jIy7XX/XdZjE0wrjKkZqvR0ADULdGb6x0zgmwyi9N4pyAehZD1Usps8R38ZInZ1c g/YPa0LriKfKg0X3YL4+LA415JAN7jQAQjZ6SPnunSPB6gJYi2LWOu6xXlKl5nW3YnAsjM4bOvUJG r1QqdVi8Jeo2NdXhUbEO8daa0gf44lSKLC+AcVb/Lmi8mBEzj4cTST1xVPPYArLS4oW9LEL35U6FG AnRX2VdArdCUhYDM6MMWSJtrr+jidjSdgIbbZksOyK4JMWNyYacfHFLjaSglml/7P2a3lXtar9Qjn ct1pjDoQ==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98.1 #2 (Red Hat Linux)) id 1u20bK-00000002hI3-16pC; Tue, 08 Apr 2025 04:30:18 +0000 Received: from out0-215.mail.aliyun.com ([140.205.0.215]) by bombadil.infradead.org with esmtps (Exim 4.98.1 #2 (Red Hat Linux)) id 1u20bG-00000002hHS-1HA2 for linux-um@lists.infradead.org; Tue, 08 Apr 2025 04:30:16 +0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=antgroup.com; s=default; t=1744086606; h=Message-ID:Date:MIME-Version:Subject:To:From:Content-Type; bh=FVk1eTGXVWxw3i4OEda44NwW29chjqvlqWUvewaxbH8=; b=nyNlOYGH5hBg56jmjJzSi7Xm4aASSK1KJuDssRMwsC1E4USIUFQQ75EL00hU67aBBJU4kOO0n1tJ0J7z+0AuNiG0c+5CR4asynYibh48zPY++7txBftYXl23hCBJh3UW2qhM6CzAmeXAFzMIY0BxZlE+LioiIKJasnF06/zXEoc= Received: from 30.174.97.68(mailfrom:tiwei.btw@antgroup.com fp:SMTPD_---.cGPMUZX_1744086594 cluster:ay29) by smtp.aliyun-inc.com; Tue, 08 Apr 2025 12:30:00 +0800 Message-ID: Date: Tue, 08 Apr 2025 12:29:53 +0800 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH AUTOSEL 6.14 25/31] um: Switch to the pthread-based helper in sigio workaround To: Sasha Levin , linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Johannes Berg , richard@nod.at, anton.ivanov@cambridgegreys.com, johannes@sipsolutions.net, linux-um@lists.infradead.org References: <20250407181054.3177479-1-sashal@kernel.org> <20250407181054.3177479-25-sashal@kernel.org> Content-Language: en-US From: "Tiwei Bie" In-Reply-To: <20250407181054.3177479-25-sashal@kernel.org> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20250407_213014_916676_BE98B2A6 X-CRM114-Status: GOOD ( 27.38 ) X-BeenThere: linux-um@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-um" Errors-To: linux-um-bounces+linux-um=archiver.kernel.org@lists.infradead.org On 2025/4/8 02:10, Sasha Levin wrote: > From: Tiwei Bie > > [ Upstream commit d295beeed2552a987796d627ba7d0985b1e2d72f ] > > The write_sigio thread and UML kernel thread share the same errno, > which can lead to conflicts when both call syscalls concurrently. > Switch to the pthread-based helper to address this issue. > > Signed-off-by: Tiwei Bie > Link: https://patch.msgid.link/20250319135523.97050-4-tiwei.btw@antgroup.com > Signed-off-by: Johannes Berg > Signed-off-by: Sasha Levin > --- > arch/um/os-Linux/sigio.c | 44 +++++++++++++++++----------------------- > 1 file changed, 19 insertions(+), 25 deletions(-) This patch depends on the helpers introduced by the below patch: https://web.git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=4f087eafdcef24b7160b097ddb9704084767b77a So it can't be backported to the stable branch alone. Please drop it. It is more of a preparation for the new features to be added in the future. If it turns out later that it is also necessary for the stable branch, I will submit a separate patchset specifically targeting it. Regards, Tiwei > > diff --git a/arch/um/os-Linux/sigio.c b/arch/um/os-Linux/sigio.c > index 9aac8def4d635..61b348a2ea974 100644 > --- a/arch/um/os-Linux/sigio.c > +++ b/arch/um/os-Linux/sigio.c > @@ -21,8 +21,7 @@ > * Protected by sigio_lock(), also used by sigio_cleanup, which is an > * exitcall. > */ > -static int write_sigio_pid = -1; > -static unsigned long write_sigio_stack; > +static struct os_helper_thread *write_sigio_td; > > /* > * These arrays are initialized before the sigio thread is started, and > @@ -48,15 +47,15 @@ static struct pollfds current_poll; > static struct pollfds next_poll; > static struct pollfds all_sigio_fds; > > -static int write_sigio_thread(void *unused) > +static void *write_sigio_thread(void *unused) > { > struct pollfds *fds, tmp; > struct pollfd *p; > int i, n, respond_fd; > char c; > > - os_set_pdeathsig(); > - os_fix_helper_signals(); > + os_fix_helper_thread_signals(); > + > fds = ¤t_poll; > while (1) { > n = poll(fds->poll, fds->used, -1); > @@ -98,7 +97,7 @@ static int write_sigio_thread(void *unused) > } > } > > - return 0; > + return NULL; > } > > static int need_poll(struct pollfds *polls, int n) > @@ -152,11 +151,10 @@ static void update_thread(void) > return; > fail: > /* Critical section start */ > - if (write_sigio_pid != -1) { > - os_kill_process(write_sigio_pid, 1); > - free_stack(write_sigio_stack, 0); > + if (write_sigio_td) { > + os_kill_helper_thread(write_sigio_td); > + write_sigio_td = NULL; > } > - write_sigio_pid = -1; > close(sigio_private[0]); > close(sigio_private[1]); > close(write_sigio_fds[0]); > @@ -220,7 +218,7 @@ int __ignore_sigio_fd(int fd) > * sigio_cleanup has already run, then update_thread will hang > * or fail because the thread is no longer running. > */ > - if (write_sigio_pid == -1) > + if (!write_sigio_td) > return -EIO; > > for (i = 0; i < current_poll.used; i++) { > @@ -279,14 +277,14 @@ static void write_sigio_workaround(void) > int err; > int l_write_sigio_fds[2]; > int l_sigio_private[2]; > - int l_write_sigio_pid; > + struct os_helper_thread *l_write_sigio_td; > > /* We call this *tons* of times - and most ones we must just fail. */ > sigio_lock(); > - l_write_sigio_pid = write_sigio_pid; > + l_write_sigio_td = write_sigio_td; > sigio_unlock(); > > - if (l_write_sigio_pid != -1) > + if (l_write_sigio_td) > return; > > err = os_pipe(l_write_sigio_fds, 1, 1); > @@ -312,7 +310,7 @@ static void write_sigio_workaround(void) > * Did we race? Don't try to optimize this, please, it's not so likely > * to happen, and no more than once at the boot. > */ > - if (write_sigio_pid != -1) > + if (write_sigio_td) > goto out_free; > > current_poll = ((struct pollfds) { .poll = p, > @@ -325,18 +323,15 @@ static void write_sigio_workaround(void) > memcpy(write_sigio_fds, l_write_sigio_fds, sizeof(l_write_sigio_fds)); > memcpy(sigio_private, l_sigio_private, sizeof(l_sigio_private)); > > - write_sigio_pid = run_helper_thread(write_sigio_thread, NULL, > - CLONE_FILES | CLONE_VM, > - &write_sigio_stack); > - > - if (write_sigio_pid < 0) > + err = os_run_helper_thread(&write_sigio_td, write_sigio_thread, NULL); > + if (err < 0) > goto out_clear; > > sigio_unlock(); > return; > > out_clear: > - write_sigio_pid = -1; > + write_sigio_td = NULL; > write_sigio_fds[0] = -1; > write_sigio_fds[1] = -1; > sigio_private[0] = -1; > @@ -394,12 +389,11 @@ void maybe_sigio_broken(int fd) > > static void sigio_cleanup(void) > { > - if (write_sigio_pid == -1) > + if (!write_sigio_td) > return; > > - os_kill_process(write_sigio_pid, 1); > - free_stack(write_sigio_stack, 0); > - write_sigio_pid = -1; > + os_kill_helper_thread(write_sigio_td); > + write_sigio_td = NULL; > } > > __uml_exitcall(sigio_cleanup);