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Date: Tue, 3 Feb 2009 17:11:56 -0600
From: Christian Peron <csjp@freebsd.org>
To: Christoph Mallon <christoph.mallon@gmx.de>
Message-ID: <20090203231155.GA69101@jnz.sqrt.ca>
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Cc: FreeBSD Hackers <freebsd-hackers@freebsd.org>,
	FreeBSD Current <freebsd-current@freebsd.org>
Subject: Re: write-only variables in src/sys/ - possible bugs
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I started following up on this and ran into an issue for these:

sys/net/bpf_buffer.c:133: warning: variable 'dst' is never read
sys/net/bpf_buffer.c:134: warning: variable 'count' is never read
sys/net/bpf_buffer.c:142: warning: variable 'dst' is never read


/*
 * Scatter-gather data copy from an mbuf chain to the current kernel buffer.
 */
void
bpf_buffer_append_mbuf(struct bpf_d *d, caddr_t buf, u_int offset, void *src,
    u_int len)
{
        const struct mbuf *m;
        u_char *dst;
        u_int count;
 
        m = (struct mbuf *)src;
        dst = (u_char *)buf + offset;
        while (len > 0) {
                if (m == NULL)
                        panic("bpf_mcopy");
                count = min(m->m_len, len);
                bcopy(mtod(m, void *), dst, count);
                m = m->m_next;
[..]

Does it not consider being passed as an argument to a function as
being read?

Cheers