Re: where to release proc.p_stats

On Friday 21 October 2005 04:32 pm, David Schultz wrote:
> On Fri, Oct 21, 2005, John Baldwin wrote:
> > On Friday 21 October 2005 09:13 am, nocool wrote:
> > > freebsd-hackersï¼Œhello
> > >
> > > 	Question about 5.4 kernel source code.
> > > 	I have some question about strust proc's initialize. Kernel use
> > > proc_zone to allocate proc items and initialize them with proc_init
> > > (sys\kern\kern_proc.c) function. In this function, we can find the
> > > field proc.p_stats is allocated with pstats_alloc(), as
> > >
> > > p->p_stats = pstats_alloc();
> > >
> > > and pstats_alloc is realized as
> > >
> > > malloc(sizeof(struct pstats), M_SUBPROC, M_ZERO|M_WAITOK);
> > >
> > > But I can't find where this field is freed. If it will not be release,
> > > will there be memory leakage?
> >
> > Heh, das_at_ forgot to call pstats_free() when he did the changes.  The
> > reason is probably because proc_fini() doesn't do anything useful because
> > we never recycle proc structs.  We should probably at least add the
> > operations there though for documentation purposes.  Something like this
> > would work I think:
>
> I didn't put in the call because we never free proc structures, but
> documenting what should happen if we ever do free them is a good
> idea.  There's a fair amount of other cleanup that needs to happen
> as well, which you can probably find in the CVS history.  (IIRC,
> I'm guilty of removing the code at a time when more things depended
> upon struct proc being type safe.  Are there any remaining reasons
> why we can't free struct procs at this point?)
>
> By the way, there's no reason why we can't fold struct pstats into
> struct proc so we don't have to allocate and free it at all.
> It's never shared, so the extra level of indirection just adds overhead.
> The main reason I didn't make this change earlier was to maintain binary
> compatibility when I backported my U-area changes to -STABLE.

Looks like some of the functions (vm_dispose_proc() and sched_destroyproc()) 
have vanished, so this is all that would be in there now:

Index: kern_proc.c
===================================================================
RCS file: /usr/cvs/src/sys/kern/kern_proc.c,v
retrieving revision 1.232
diff -u -r1.232 kern_proc.c
--- kern_proc.c 2 Oct 2005 23:27:56 -0000       1.232
+++ kern_proc.c 21 Oct 2005 21:21:45 -0000
_at__at_ -196,8 +196,17 _at__at_
 static void
 proc_fini(void *mem, int size)
 {
+#ifdef notnow
+       struct proc *p;

+       p = (struct proc *)mem;
+       pstats_free(p->p_stats);
+       ksegrp_free(FIRST_KSEGRP_IN_PROC(p));
+       thread_free(FIRST_THREAD_IN_PROC(p));
+       mtx_destroy(&p->p_mtx);
+#else
        panic("proc reclaimed");
+#endif
 }

 /*


-- 
John Baldwin <jhb_at_FreeBSD.org>  <><  http://www.FreeBSD.org/~jhb/
"Power Users Use the Power to Serve"  =  http://www.FreeBSD.org