From mboxrd@z Thu Jan  1 00:00:00 1970
Message-ID: <ee9e417a040604093860e7fcf5@mail.gmail.com>
Date: Fri,  4 Jun 2004 12:38:56 -0400
From: Russ Cox <russcox@gmail.com>
To: Fans of the OS Plan 9 from Bell Labs <9fans@cse.psu.edu>
Subject: Re: [9fans] stack reclamation on Unix using clone, rfork_thread, etc.
In-Reply-To: <6.1.1.1.0.20040604175442.021d8420@pop.free.fr>
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References: <200406041533.i54FXNm29967@plg2.math.uwaterloo.ca>
	<6.1.1.1.0.20040604175442.021d8420@pop.free.fr>
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> void
> exit_thread()
>   {
>          struct segment * s;
> 
>          lock(&addrspace);
>          for (s = addrspace.tofree; s; s = s->next)
>                  free(s->addr);
>          if (--refcount) {
>                  s = find_segment_from_id(get_my_thread_id());
>                  list_remove(s);
>                  list_add(tofree, s);
>                  unlock(&addrspace);
>          }
> }

this isn't safe because you keep using the stack
after you unlock &addrspace, so someone else
might come along and free it out from under you
before you manage to exit.  the inferno version
posted by charles fixes this.

unfortunately, i'm trying not to assume that all the threads
will exit with my exit function, so this approach isn't
really an option.

russ