Fix bugs causing hangs - #368
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Currently, when cygwin app is launched, the console input mode is
set to tty::cygwin, even if the stdin is not a console. However,
it is not necessary because the cygwin app does not use stdin.
This also applies to stdout and stderr.
With this patch, the console mode is set only when std{in,out,err}
is a console for the cygwin app for better coexistence with non-
cygwin apps.
This is a prerequisite for the experimental backport of Takashi Yano's
v15 console-mode patch to msys2-3.6.10. The release branch's later,
already-applied suspension-before-mode ordering is preserved.
(cherry picked from commit bbd3710)
Assisted-by: GPT-6
Signed-off-by: Takashi Yano <takashi.yano@nifty.ne.jp>
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Previously, if two non-cygwin apps are started and one of them exits first, the other one lost appropriate console mode, since the first one restored it to tty::cygwin. This patch counts the active console process whose pgid is pgid of the tty and if the result is zero (means the last non-cygwin foreground process), restore console mode. To avoid race issue between apps modifying console mode simultaneously, this patch also introduce a mutex named `cons_mode_mutex`. Known limitation: In the case of non-overlayed spawn, there still exists a small window in which another non-cygwin process may restore tty::cygwin mode even though new non-cygwin app is about to start. In addition: Avoid the cleanup/startup deadlock: cleanup can hold `cons_mode_mutex` while waiting for a console master that a new owner cannot start until acquiring that mutex. Startup must precede the mode-mutex wait without changing the handshake or mode serialization. Backport the complete upstream v18 patch after the prerequisite: https://inbox.sourceware.org/cygwin-patches/20260919004709.26360-1-takashi.yano@nifty.ne.jp/ Adapt only the three existing msys2-3.6.10 preimage/context spellings. Fixes: 48285aa ("Cygwin: console: Fix handling of Ctrl-S in Win7.") Co-authored-by: Johannes Schindelin <Johannes.Schindelin@gmx.de> Reviewed-by: Johannes Schindelin <Johannes.Schindelin@gmx.de> Assisted-by: GPT-6 Signed-off-by: Takashi Yano <takashi.yano@nifty.ne.jp> Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
With the commit 733d5a9 ("Cygwin: console: Ensure the master thread runs only when it is supposed to"), the process which calls set_disable_master_thread() hangs if the con.owner already exited, because set_disable_master_thread() waits for cons_master_thread accepting the status change and reflecting the current status to master_thread_suspended. With this patch, set_disable_master_thread() is aborted if the owner process no longer exists to avoid this hang. Backport the complete upstream v5 patch unchanged after v18: https://inbox.sourceware.org/cygwin-patches/20260923223230.3504-1-takashi.yano@nifty.ne.jp/ Addresses: https://cygwin.com/pipermail/cygwin/2026-September/260037.html Fixes: 733d5a9 ("Cygwin: console: Ensure the master thread runs only when it is supposed to") Reported-by: Jay Libove Alzina <libove@felines.org> Co-authored-by: Johannes Schindelin <Johannes.Schindelin@gmx.de> Reviewed-by: Johannes Schindelin <Johannes.Schindelin@gmx.de> Assisted-by: GPT-6 Signed-off-by: Takashi Yano <takashi.yano@nifty.ne.jp> Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
dscho
marked this pull request as ready for review
September 24, 2026 12:06
This was referenced Sep 24, 2026
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* msys2-runtime: Fix bugs causing hangs This Pull Request backports three changes. The first one is a prerequisite for the second, and the third is also needed to fix those bugs that caused hangs that I first saw reported in #6445: 1. `c892dfe93e`: the [complete prerequisite](cygwin/cygwin@bbd3710), including the companion `dtable.cc` standard-handle change. 2. `92c1e00a38`: [console-mode v18](https://inbox.sourceware.org/cygwin-patches/20260919004709.26360-1-takashi.yano@nifty.ne.jp/), including reconciliation on signal and read-retry paths. 3. `c770e1b9fa`: [owner-exit v5](https://inbox.sourceware.org/cygwin-patches/20260923223230.3504-1-takashi.yano@nifty.ne.jp/), including the processed-input fallback for an unavailable console master. I verified that these patches are enough to address the hangs demonstrated by the reproducer provided in msys2/msys2-runtime#351. This fixes msys2/msys2-runtime#351 This corresponds to msys2/msys2-runtime#368 * msys2-runtime: fix pkgrel Ooops! My script has a bug! Co-authored-by: Christoph Reiter <reiter.christoph@gmail.com> --------- Co-authored-by: Christoph Reiter <reiter.christoph@gmail.com>
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* msys2-runtime: Fix bugs causing hangs This Pull Request backports three changes. The first one is a prerequisite for the second, and the third is also needed to fix those bugs that caused hangs that I first saw reported in msys2/MSYS2-packages#6445: 1. `c892dfe93e`: the [complete prerequisite](cygwin/cygwin@bbd3710), including the companion `dtable.cc` standard-handle change. 2. `92c1e00a38`: [console-mode v18](https://inbox.sourceware.org/cygwin-patches/20260919004709.26360-1-takashi.yano@nifty.ne.jp/), including reconciliation on signal and read-retry paths. 3. `c770e1b9fa`: [owner-exit v5](https://inbox.sourceware.org/cygwin-patches/20260923223230.3504-1-takashi.yano@nifty.ne.jp/), including the processed-input fallback for an unavailable console master. I verified that these patches are enough to address the hangs demonstrated by the reproducer provided in msys2/msys2-runtime#351. This fixes msys2/msys2-runtime#351 This corresponds to msys2/msys2-runtime#368 * msys2-runtime: fix pkgrel Ooops! My script has a bug! Co-authored-by: Christoph Reiter <reiter.christoph@gmail.com> --------- Co-authored-by: Christoph Reiter <reiter.christoph@gmail.com> Source: msys2/MSYS2-packages@bca80c8
dscho
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In the MSYS2 project, there were several reports of newly-introduced hangs, e.g. msys2/msys2-runtime#351 and msys2/MSYS2-packages#6445 (comment). It took a good while to figure out how to fix this properly, with two separate fixes needing 18 and 5 iterations, respectively, on the cygwin-patches mailing list. This branch merges [MSYS2 runtime PR #368](msys2/msys2-runtime#368). The sole `dtable.cc` conflict preserves GFW's pcon-backed PTY detection and genuine console handles. Separately, tests running in CI builds are added that replicate the reproducer of issue 351 and a separate Ctrl+C test that covers [Takashi's pipeline scenario](https://inbox.sourceware.org/cygwin-patches/20260923105326.d57b0710f1519e32b9c5d496@nifty.ne.jp/): the Cygwin sleeper must be interrupted via Ctrl+C even when the native side owns console input. The original DLL already passed this test, so it protects against regressions in this existing behavior.
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This Pull Request backports three changes. The first one is a prerequisite for the second, and the third is also needed to fix those bugs that caused hangs that I first saw reported in msys2/MSYS2-packages#6445:
c892dfe93e: the complete prerequisite, including the companiondtable.ccstandard-handle change.92c1e00a38: console-mode v18, including reconciliation on signal and read-retry paths.c770e1b9fa: owner-exit v5, including the processed-input fallback for an unavailable console master.I verified that these patches are enough to address the hangs demonstrated by the reproducer provided in #351.
This fixes #351