Re: [9fans] wait hang

["Russ Cox" <rsc@swtch.com>]

> since 20 is much less than 128, this can't be the kernel.  i think the
> problem is in the discarded wait messages here: rc/plan9.c/^Waitfor

Where do you see discarded wait messages?

> int
> Waitfor(int pid, int)
> {
>         thread *p;
>         Waitmsg *w;
>         char errbuf[ERRMAX];
>
>         while((w = wait()) != nil){
>                 if(w->pid==pid){
>                         setstatus(w->msg);
>                         free(w);
>                         return 0;
>                 }
>                 for(p = runq->ret;p;p = p->ret)
>                         if(p->pid==w->pid){
>                                 p->pid=-1;
>                                 strcpy(p->status, w->msg);
>                         }

This loop is trying to save the information about the
wait message.  But it doesn't seem to get consulted
anywhere, and I have never understood why that particular
linked list is the one to be looking through.

Russ