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 C8239C36002 for ; Wed, 19 Mar 2025 13:55:44 +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: MIME-Version:References:In-Reply-To:Message-Id:Date:Subject:Cc:To:From: Reply-To:Content-Type:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=yLD2eDsHScWzoc++hy0wPvCMEB6k8Y9b9/+bzI6FCa4=; b=w+GeFw8vFS+xUXnLcJYQaHC82F 0utgP4E2AE3/J6ILi9oZXiDPp6X2FWQu5Ys/8fOqKU/Vb6MvjnPgqYoDJtKdEKf6+TCGETKMz9A44 WxG9bkFlN/V8UZqA/C+Z0J0qplBBKmWr07n7h5RECK03Xf4vM/Jd9Wr3HxKeSeIgEwqcBALmTwiPN FJPWZEHrRstOQ3Q8RV+iQ5QPrh6XSzd6uf+YTMtxvsq4F0gE0VIrjp2MXv1tbtDa3wA6INVNMj1qF kbFeMzC0YvkgxW9Rc4LUCp9eJp0xIhS0JgBDZ5F024e64G28pXmVthzYZn/ZvL4ExbVcCcCutQiX5 AVSj0hxQ==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98 #2 (Red Hat Linux)) id 1tuttY-000000098VV-13T2; Wed, 19 Mar 2025 13:55:44 +0000 Received: from out0-208.mail.aliyun.com ([140.205.0.208]) by bombadil.infradead.org with esmtps (Exim 4.98 #2 (Red Hat Linux)) id 1tuttT-000000098TE-2HVy for linux-um@lists.infradead.org; Wed, 19 Mar 2025 13:55:42 +0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=antgroup.com; s=default; t=1742392537; h=From:To:Subject:Date:Message-Id:MIME-Version; bh=yLD2eDsHScWzoc++hy0wPvCMEB6k8Y9b9/+bzI6FCa4=; b=BG4oYDdBx9W7Z0Ml8oSCF43TnzUmUbIBz3M1rCxCML34To1rnsbyhPbvCAkivcp+ETOm7o+AILR74lG7EH/7MntIvodbsC8aJRk2lMhaqaOuyDGtkH1AfjHkWxYB09MzxLsFeR5HpgiggL1WRnSy5CPvNefroLCc6qs+NByAa2I= Received: from ubuntu..(mailfrom:tiwei.btw@antgroup.com fp:SMTPD_---.byXmrk9_1742392534 cluster:ay29) by smtp.aliyun-inc.com; Wed, 19 Mar 2025 21:55:34 +0800 From: "Tiwei Bie" To: richard@nod.at, anton.ivanov@cambridgegreys.com, johannes@sipsolutions.net Cc: , "Tiwei Bie" Subject: [PATCH v3 3/4] um: Switch to the pthread-based helper in sigio workaround Date: Wed, 19 Mar 2025 21:55:22 +0800 Message-Id: <20250319135523.97050-4-tiwei.btw@antgroup.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20250319135523.97050-1-tiwei.btw@antgroup.com> References: <20250319135523.97050-1-tiwei.btw@antgroup.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20250319_065539_908197_A5B99E9E X-CRM114-Status: GOOD ( 17.38 ) 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 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 --- arch/um/os-Linux/sigio.c | 44 +++++++++++++++++----------------------- 1 file changed, 19 insertions(+), 25 deletions(-) diff --git a/arch/um/os-Linux/sigio.c b/arch/um/os-Linux/sigio.c index 9aac8def4d63..61b348a2ea97 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); -- 2.34.1