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SubjectFutex wait is not interrupted by signals if no timeout is provided
I've observed a strange behaviour of futexes that I believe to be a bug.  If a 
signal is delivered while a futex wait is in progress, the wait will be
interrupted, but only if that wait had a timeout. I expect it to be
interrupted regardless of whether a timeout is provided. The following
runnable snippet demonstrates this:

void handler(int) { printf("SIGINT\n"); }
int main() {
signal(SIGINT,handler);
int i=2;
printf("1\n");
syscall(SYS_futex, &i, FUTEX_WAIT, 2, &(struct timespec){.tv_sec=1000});
printf("2\n");
syscall(SYS_futex, &i, FUTEX_WAIT, 2, NULL);
printf("3\n");
}

Pressing ^C once causes the first wait to terminate, and '2' to be printed.
But repeatedly pressing it after that does not allow the program to make
progress.

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