Re: [PATCH] signals: work around random wakeups in sigsuspend()

[Peter Zijlstra]

On Tue, Jan 26, 2016 at 10:10:09PM +0100, Oleg Nesterov wrote:

> And, ironically, there is another more serious "reverse" problem ;) 
> sigsuspend()
> orany other user of -ERESTARTNOHAND can "miss" the signal, in a sense that the
> kernel can wrongly restart this syscall after return from signal handler. This
> is not trivial to fix..

So I'm not entirely sure I get what you mean there. But it did get me to
look at the patch again:

+       while (!signal_pending(current)) {
+               __set_current_state(TASK_INTERRUPTIBLE);
+               schedule();
+       }

That should very much be:

        for (;;) {
                set_current_state(TASK_INTERRUPTIBLE);
                if (signal_pending(current))
                        break;
                schedule();
        }
        __set_current_state(TASK_RUNNING);