From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from conuserg-09.nifty.com (conuserg-09.nifty.com [210.131.2.76]) by sourceware.org (Postfix) with ESMTPS id 99A443858427 for ; Wed, 23 Mar 2022 08:48:35 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.1 sourceware.org 99A443858427 Authentication-Results: sourceware.org; dmarc=fail (p=none dis=none) header.from=nifty.ne.jp Authentication-Results: sourceware.org; spf=fail smtp.mailfrom=nifty.ne.jp Received: from localhost.localdomain (ak036016.dynamic.ppp.asahi-net.or.jp [119.150.36.16]) (authenticated) by conuserg-09.nifty.com with ESMTP id 22N8mBOl031859; Wed, 23 Mar 2022 17:48:16 +0900 DKIM-Filter: OpenDKIM Filter v2.10.3 conuserg-09.nifty.com 22N8mBOl031859 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=nifty.ne.jp; s=dec2015msa; t=1648025296; bh=63il32n8Fual98v569mA51cPvkFK7YLUiBCc2wXCNFI=; h=From:To:Cc:Subject:Date:From; b=1ZdMOafVDjCZVhovPLhXpgKYJBTrhQuBY+eWQr/fCbap4LhzwsY+4iwnuapMwd0nD iEXIsMNFr6SxHkUWOyttCnaTp22kcwhZ+b6uUiPfwZ16Xf3ZCwrWZffqPfyOGlMVQe rL8VPnzv9JsgjnSCKqkL/jvDwT50Hi4NLlalb/Gxwuqm6yc03+s8I0d6Oqg5iv3b1c l0yCs4ZeKPgfn2VEg3QknGgpAd7pcxWxEutQfaY3g9e8Zh+cOz5Y7M/qu40GnvNc73 5Vi8euUkXnZj6txuHWHbKgm9lIdAjsvm5jWyQAAUoTgr+EbwadUjuS4OF6EqXqAzlS 9D0dvHUZN8h9Q== X-Nifty-SrcIP: [119.150.36.16] From: Takashi Yano To: cygwin-patches@cygwin.com Subject: [PATCH v2] Cygwin: pipe: Avoid deadlock for non-cygwin writer. Date: Wed, 23 Mar 2022 17:48:01 +0900 Message-Id: <20220323084802.1917-1-takashi.yano@nifty.ne.jp> X-Mailer: git-send-email 2.35.1 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Spam-Status: No, score=-10.9 required=5.0 tests=BAYES_00, DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, DKIM_VALID_EF, GIT_PATCH_0, RCVD_IN_DNSWL_NONE, SPF_HELO_NONE, SPF_PASS, TXREP, T_SCC_BODY_TEXT_LINE autolearn=ham autolearn_force=no version=3.4.4 X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) on server2.sourceware.org X-BeenThere: cygwin-patches@cygwin.com X-Mailman-Version: 2.1.29 Precedence: list List-Id: Cygwin core component patch submission and discussion List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 23 Mar 2022 08:48:39 -0000 - As mentioned in commit message of the commit b531d6b0, if multiple writers including non-cygwin app exist, the non-cygwin app cannot detect pipe closure on the read side when the pipe is created by system account or the the pipe creator is running as service. This is because query_hdl which is held in write side also is a read end of the pipe, so the pipe still alive for the non-cygwin app even after the reader is closed. To avoid this problem, this patch lets all processes in the same process group close query_hdl using newly introduced internal signal __SIGNONCYGCHLD when non-cygwin app is started. Addresses: https://cygwin.com/pipermail/cygwin/2022-March/251097.html --- winsup/cygwin/sigproc.cc | 9 +++++++++ winsup/cygwin/sigproc.h | 1 + winsup/cygwin/spawn.cc | 7 ++++++- 3 files changed, 16 insertions(+), 1 deletion(-) diff --git a/winsup/cygwin/sigproc.cc b/winsup/cygwin/sigproc.cc index d3f2b0c6a..9a2f75861 100644 --- a/winsup/cygwin/sigproc.cc +++ b/winsup/cygwin/sigproc.cc @@ -1477,6 +1477,15 @@ wait_sig (VOID *) clearwait = true; } break; + case __SIGNONCYGCHLD: + cygheap_fdenum cfd (false); + while (cfd.next () >= 0) + if (cfd->get_dev () == FH_PIPEW) + { + fhandler_pipe *pipe = (fhandler_pipe *)(fhandler_base *) cfd; + pipe->close_query_handle (); + } + break; } if (clearwait && !have_execed) proc_subproc (PROC_CLEARWAIT, 0); diff --git a/winsup/cygwin/sigproc.h b/winsup/cygwin/sigproc.h index 23287c85b..d037eaec3 100644 --- a/winsup/cygwin/sigproc.h +++ b/winsup/cygwin/sigproc.h @@ -24,6 +24,7 @@ enum __SIGSETPGRP = -(_NSIG + 9), __SIGTHREADEXIT = -(_NSIG + 10), __SIGPENDINGALL = -(_NSIG + 11), + __SIGNONCYGCHLD = -(_NSIG + 12), }; #endif diff --git a/winsup/cygwin/spawn.cc b/winsup/cygwin/spawn.cc index fb3d09d84..a32a4180c 100644 --- a/winsup/cygwin/spawn.cc +++ b/winsup/cygwin/spawn.cc @@ -28,6 +28,7 @@ details. */ #include "tls_pbuf.h" #include "winf.h" #include "ntdll.h" +#include "shared_info.h" static const suffix_info exe_suffixes[] = { @@ -645,8 +646,12 @@ child_info_spawn::worker (const char *prog_arg, const char *const *argv, && (fd == fileno_stdout || fd == fileno_stderr)) { fhandler_pipe *pipe = (fhandler_pipe *)(fhandler_base *) cfd; - pipe->close_query_handle (); pipe->set_pipe_non_blocking (false); + tty_min *t = cygwin_shared->tty.get_cttyp (); + if (t) + /* Emit __SIGNONCYGCHLD to let all processes in the + process group close query_hdl. */ + t->kill_pgrp (__SIGNONCYGCHLD); } else if (cfd->get_dev () == FH_PIPER && fd == fileno_stdin) { -- 2.35.1