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To: Bruce Evans <bde@zeta.org.au>
Cc: Peter Wemm <peter@wemm.org>, <arch@FreeBSD.ORG>
Subject: Re: Removing ptrace(2)'s dependency on procfs(5)
References: <20011006221156.X824-100000@delplex.bde.org>
From: Dag-Erling Smorgrav <des@ofug.org>
Date: 06 Oct 2001 15:31:52 +0200
In-Reply-To: <20011006221156.X824-100000@delplex.bde.org>
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Bruce Evans <bde@zeta.org.au> writes:
> I noticed the following bugs:
> - PHOLD()/PRELE() is now missing from the register access functions of
>   ptrace().  This makes the bogus EIO error in PROCFS_ACTION() much less
>   unlikely.

Aieee, thanks for catching that before I committed!

BTW, I'm intrigued by the following bit of code in kern_sig.c:

                        do {
                                mtx_lock_spin(&sched_lock);
                                stop(p);
                                PROC_UNLOCK_NOSWITCH(p);
                                DROP_GIANT_NOSWITCH();
                                p->p_stats->p_ru.ru_nivcsw++;
                                mi_switch();
                                mtx_unlock_spin(&sched_lock);
                                PICKUP_GIANT();
                                PROC_LOCK(p);
                        } while (!trace_req(p)
                                 && p->p_flag & P_TRACED);

It's the only reference to trace_req() (defined in sys_process.c) in
the entire tree, and trace_req() has been a constant since revision
1.1 of sys_process.c, and true since revision 1.4 (1994/08/08), so
this loop will always execute exactly once.  Is there a good reason
not to simply axe trace_req() and unroll the loop?

DES
-- 
Dag-Erling Smorgrav - des@ofug.org

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