[PATCH] Cygwin: signa: Redesign signal queue handling

[Christian Franke]

Takashi Yano wrote:
> The previous implementation of the signal queue behaves as:
> 1) Signals in the queue are processed in a disordered manner.
> 2) If the same signal is already in the queue, new signal is discarded.
>
> Strictly speaking, these behaviours do not violate POSIX. However,
> these could be a cause of unexpected behaviour in some software. In
> Linux, some important signals such as SIGSTOP/SIGCONT do not seem to
> behave like that.
>
> With this patch prevents all signals from that issues by redesigning
> the signal queue, Only the exception is the case that the process is
> in the PID_STOPPED state. In this case, SIGCONT/SIGKILL should be
> processed prior to the other signals in the queue.
>
> Addresses:https://cygwin.com/pipermail/cygwin/2025-March/257582.html
> ...

A quick test with many runs of 'lostsig' testcase with or without 
'taskset 0x1' no longer shows any problems. No SIGALRM were lost (not 
required), [SIGTERM] is always printed after all [SIGALRM] (not 
required), SIGCONT is never lost. The previous 'timersig' testcase also 
still succeeds.



-- 
Thanks,
Christian