From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from conuserg-12.nifty.com (conuserg-12.nifty.com [210.131.2.79]) by sourceware.org (Postfix) with ESMTPS id 0B5843858C50 for ; Wed, 30 Mar 2022 00:21:10 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.1 sourceware.org 0B5843858C50 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 (ak044095.dynamic.ppp.asahi-net.or.jp [119.150.44.95]) (authenticated) by conuserg-12.nifty.com with ESMTP id 22U0Kfr1014748; Wed, 30 Mar 2022 09:20:46 +0900 DKIM-Filter: OpenDKIM Filter v2.10.3 conuserg-12.nifty.com 22U0Kfr1014748 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=nifty.ne.jp; s=dec2015msa; t=1648599646; bh=65bxq6Pnil4KPOsMKMAejT/gHalB/qf46Af302J4pbQ=; h=From:To:Cc:Subject:Date:From; b=TUS4hoHLQicfFIMu+sQ7gcYfkxuTF0Qwaf+CfqHVvO5DS8R3+WTNdU2MN6LEwI2Bi 8cgoGmf3ejmUkszRkMT8epwCLnaivxqD8cseZIiOWFVEc/M43Mzqyw00Hr46a1C5C5 31ocDWhy79UAYa6bw07D+j4UMdXJGAPmNRYpSg9EnBwFwmiwu2DMZEE77JQlxL6yWJ 2kkwy+iELgU2UE2cabxxEhfveEYVyFWpzsAur2RvT6SXTuni044I9vHl/0h+n1j0uS YvYZBx7BiS6RZl3ONXL4i1yR4M1tsgKihfjApsnUwWeTRl2n5fOMtQL6EgRpAXnKOx d/+NaqvpQ4cZw== X-Nifty-SrcIP: [119.150.44.95] From: Takashi Yano To: cygwin-patches@cygwin.com Subject: [PATCH v5] Cygwin: pipe: Avoid deadlock for non-cygwin writer. Date: Wed, 30 Mar 2022 09:20:38 +0900 Message-Id: <20220330002038.39004-1-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=-10.8 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, 30 Mar 2022 00:21:13 -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 is 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/fhandler.h | 16 ++++++++++++++++ winsup/cygwin/fhandler_pipe.cc | 23 +++++++++++++++++++++++ winsup/cygwin/sigproc.cc | 10 ++++++++++ winsup/cygwin/sigproc.h | 1 + winsup/cygwin/spawn.cc | 18 +++++++++++++++++- 5 files changed, 67 insertions(+), 1 deletion(-) diff --git a/winsup/cygwin/fhandler.h b/winsup/cygwin/fhandler.h index b87160edb..9e6e7c933 100644 --- a/winsup/cygwin/fhandler.h +++ b/winsup/cygwin/fhandler.h @@ -1194,6 +1194,7 @@ private: HANDLE hdl_cnt_mtx; HANDLE query_hdl_proc; HANDLE query_hdl_value; + HANDLE query_hdl_close_req_evt; uint64_t pipename_key; DWORD pipename_pid; LONG pipename_id; @@ -1255,9 +1256,24 @@ public: CloseHandle (query_hdl); query_hdl = NULL; } + if (query_hdl_close_req_evt) + { + CloseHandle (query_hdl_close_req_evt); + query_hdl_close_req_evt = NULL; + } } bool reader_closed (); HANDLE temporary_query_hdl (); + bool need_close_query_hdl () + { + return query_hdl_close_req_evt ? + IsEventSignalled (query_hdl_close_req_evt) : false; + } + void request_close_query_hdl () + { + if (query_hdl_close_req_evt) + SetEvent (query_hdl_close_req_evt); + } }; #define CYGWIN_FIFO_PIPE_NAME_LEN 47 diff --git a/winsup/cygwin/fhandler_pipe.cc b/winsup/cygwin/fhandler_pipe.cc index aef0bf6be..270ba34a0 100644 --- a/winsup/cygwin/fhandler_pipe.cc +++ b/winsup/cygwin/fhandler_pipe.cc @@ -566,6 +566,8 @@ fhandler_pipe::fixup_after_fork (HANDLE parent) fork_fixup (parent, select_sem, "select_sem"); if (query_hdl) fork_fixup (parent, query_hdl, "query_hdl"); + if (query_hdl_close_req_evt) + fork_fixup (parent, query_hdl_close_req_evt, "query_hdl_close_req_evt"); fhandler_base::fixup_after_fork (parent); ReleaseMutex (hdl_cnt_mtx); @@ -616,6 +618,16 @@ fhandler_pipe::dup (fhandler_base *child, int flags) ftp->close (); res = -1; } + else if (query_hdl_close_req_evt && + !DuplicateHandle (GetCurrentProcess (), query_hdl_close_req_evt, + GetCurrentProcess (), + &ftp->query_hdl_close_req_evt, + 0, !(flags & O_CLOEXEC), DUPLICATE_SAME_ACCESS)) + { + __seterrno (); + ftp->close (); + res = -1; + } ReleaseMutex (hdl_cnt_mtx); debug_printf ("res %d", res); @@ -635,6 +647,8 @@ fhandler_pipe::close () WaitForSingleObject (hdl_cnt_mtx, INFINITE); if (query_hdl) CloseHandle (query_hdl); + if (query_hdl_close_req_evt) + CloseHandle (query_hdl_close_req_evt); int ret = fhandler_base::close (); ReleaseMutex (hdl_cnt_mtx); CloseHandle (hdl_cnt_mtx); @@ -868,9 +882,18 @@ fhandler_pipe::create (fhandler_pipe *fhs[2], unsigned psize, int mode) 0, sa->bInheritHandle, DUPLICATE_SAME_ACCESS)) goto err_close_hdl_cnt_mtx0; + if (fhs[1]->query_hdl) + { + fhs[1]->query_hdl_close_req_evt = CreateEvent (sa, TRUE, FALSE, NULL); + if (!fhs[1]->query_hdl_close_req_evt) + goto err_close_hdl_cnt_mtx1; + } + res = 0; goto out; +err_close_hdl_cnt_mtx1: + CloseHandle (fhs[1]->hdl_cnt_mtx); err_close_hdl_cnt_mtx0: CloseHandle (fhs[0]->hdl_cnt_mtx); err_close_query_hdl: diff --git a/winsup/cygwin/sigproc.cc b/winsup/cygwin/sigproc.cc index d3f2b0c6a..62df96652 100644 --- a/winsup/cygwin/sigproc.cc +++ b/winsup/cygwin/sigproc.cc @@ -1477,6 +1477,16 @@ 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; + if (pipe->need_close_query_hdl ()) + 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..68ce49f6f 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[] = { @@ -631,6 +632,7 @@ child_info_spawn::worker (const char *prog_arg, const char *const *argv, if (!iscygwin ()) { + bool need_send_sig = false; int fd; cygheap_fdenum cfd (false); while ((fd = cfd.next ()) >= 0) @@ -645,14 +647,28 @@ 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); + pipe->request_close_query_hdl (); + need_send_sig = true; } else if (cfd->get_dev () == FH_PIPER && fd == fileno_stdin) { fhandler_pipe *pipe = (fhandler_pipe *)(fhandler_base *) cfd; pipe->set_pipe_non_blocking (false); } + + if (need_send_sig) + { + tty_min dummy_tty; + dummy_tty.ntty = (fh_devices) myself->ctty; + dummy_tty.pgid = myself->pgid; + tty_min *t = cygwin_shared->tty.get_cttyp (); + if (!t) /* If tty is not allocated, use dummy_tty instead. */ + t = &dummy_tty; + /* Emit __SIGNONCYGCHLD to let all processes in the + process group close query_hdl. */ + t->kill_pgrp (__SIGNONCYGCHLD); + } } bool stdin_is_ptys = false; -- 2.35.1