On Sat, 16 Apr 2022 18:16:50 +0900 Takashi Yano wrote: > On Fri, 15 Apr 2022 21:09:05 +0300 > Alexey Izbyshev wrote: > > Hi, > > > > I've discovered that pressing Ctrl-C in a Cygwin ssh session running the > > following command can cause a deadlock: > > > > $ while python -c ''; do :; done > > > > The exact native application doesn't matter here, e.g. "ping -n 1 > > localhost >/dev/null" instead of "python -c ''" also "works". > > > > The deadlock is most easily triggered when CPU is fully loaded. It takes > > no more than 20 tries on my machine to hit it (and when I first saw it, > > it was on the first try). > > > > When the deadlock is triggered, there are conhost.exe and > > cygwin-console-helper.exe processes, but there is no python. > > > > The exact process tree varies depending on Cygwin version. With the > > vanilla 3.3.4 (the root is bash spawned by sshd): > > > > bash---bash-+-conhost.exe > > `-cygwin-console-helper.exe > > > > With 20220301 snapshot > > (https://cygwin.com/snapshots/x86/cygwin1-20220301.dll.xz), I get one of > > the two following trees with an extra conhost.exe process: > > > > bash---bash-+-conhost.exe > > |-conhost.exe > > `-cygwin-console-helper.exe > > > > or > > > > bash---bash-+-conhost.exe > > | `-cygwin-console-helper.exe > > `-conhost.exe > > > > I was testing with 32-bit Cygwin on x64 Windows 10 21H2. > > Thanks for the report. I could reproduce the issue. > I also found the current git master does not have this issue, > while cygwin-3_3-branch does. > > Now I am identifying which patch solved the issue. > One is obviously: > https://cygwin.com/pipermail/cygwin-patches/2022q2/011870.html > however, this was applied also for cygwin-3_3-branch. Therefore, > another patch also should affect this issue.
I identified the cause and applied a workaround patch. The countermeasure version is available at: https://tyan0.yr32.net/cygwin/x86/test/cygwin1-20220418.dll.xz https://tyan0.yr32.net/cygwin/x86_64/test/cygwin1-20220418.dll.xz Could you please test? -- Takashi Yano <takashi.y...@nifty.ne.jp> -- Problem reports: https://cygwin.com/problems.html FAQ: https://cygwin.com/faq/ Documentation: https://cygwin.com/docs.html Unsubscribe info: https://cygwin.com/ml/#unsubscribe-simple
