[PATCH] Cygwin: sigproc: Do not send signal to myself if exiting.
Takashi Yano
takashi.yano@nifty.ne.jp
Fri Nov 19 17:14:52 GMT 2021
On Fri, 19 Nov 2021 16:53:57 +0100
Corinna Vinschen wrote:
> On Nov 19 16:51, Corinna Vinschen wrote:
> > Hi Takashi,
> >
> > On Nov 19 20:50, Takashi Yano wrote:
> > > - This patch fixes the issue that process sometimes hangs for 60
> > > seconds with the following scenario.
> > > 1) Open command prompt.
> > > 2) Run "c:\cygwin64\bin\bash -l"
> > > 3) Compipe the following source with mingw compiler.
> > > /*--- Begin ---*/
> > > #include <stdio.h>
> > > int main() {return getchar();}
> > > /*---- End ----*/
> > > 3) Run "tcsh -c ./a.exe"
> > > 4) Hit Ctrl-C.
> > > ---
> > > winsup/cygwin/sigproc.cc | 4 ++++
> > > 1 file changed, 4 insertions(+)
> > >
> > > diff --git a/winsup/cygwin/sigproc.cc b/winsup/cygwin/sigproc.cc
> > > index 97211edcf..9160dd160 100644
> > > --- a/winsup/cygwin/sigproc.cc
> > > +++ b/winsup/cygwin/sigproc.cc
> > > @@ -603,6 +603,10 @@ sig_send (_pinfo *p, siginfo_t& si, _cygtls *tls)
> > > its_me = false;
> > > }
> > >
> > > + /* Do not send signal to myself if exiting. */
> > > + if (its_me && exit_state > ES_EXIT_STARTING && si.si_signo > 0)
> > > + goto out;
> > > +
> > > if (its_me)
> > > sendsig = my_sendsig;
> > > else
> > > --
> > > 2.33.0
> >
> > Isn't that already handled in wait_sig? What's the difference here?
>
> ...and where exactly is it waiting 60 secs?
If sending signal to myself with exit_state > ES_EXIT_STARGING,
wait_for_completion in sig_send() is set to true. Therefore,
sig_send() waits for pack.wakeup event for WSSC (60000 msec) here:
/* No need to wait for signal completion unless this was a signal to
this process.
If it was a signal to this process, wait for a dispatched signal.
Otherwise just wait for the wait_sig to signal that it has finished
processing the signal. */
if (wait_for_completion)
{
sigproc_printf ("Waiting for pack.wakeup %p", pack.wakeup);
rc = WaitForSingleObject (pack.wakeup, WSSC);
ForceCloseHandle (pack.wakeup);
}
However, thread wait_sig ignores the signal here:
/* Don't process signals when we start exiting */
if (exit_state > ES_EXIT_STARTING && pack.si.si_signo > 0)
continue;
and does not call SetEvent (pack.wakeup).
As a result, sig_send() hangs for 60 secs.
With this patch, sig_send() does not send signal which will
be ignored in wait_sig().
--
Takashi Yano <takashi.yano@nifty.ne.jp>
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