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replace m_defrag with something more suitable

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Sam Leffler 2005-03-29 20:54:31 +00:00
parent a0aef338f1
commit 99d258fdc5
1 changed files with 88 additions and 3 deletions
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91
sys/dev/ath/if_ath.c
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@ -2894,6 +2894,89 @@ ath_tx_cleanup(struct ath_softc *sc)
ath_tx_cleanupq(sc, &sc->sc_txq[i]);
}
/*
* Defragment an mbuf chain, returning at most maxfrags separate
* mbufs+clusters. If this is not possible NULL is returned and
* the original mbuf chain is reclaimed. We use two techniques:
* collapsing consecutive mbufs and replacing consecutive mbufs
* by a cluster.
*/
static struct mbuf *
ath_defrag(struct mbuf *m0, int how, int maxfrags)
{
struct mbuf *m, *n, *n2, **prev;
u_int curfrags;
/*
* Calculate the current number of frags.
*/
curfrags = 0;
for (m = m0; m != NULL; m = m->m_next)
curfrags++;
/*
* First, try to collapse mbufs. Note that we always collapse
* towards the front so we don't need to deal with moving the
* pkthdr. This may be suboptimal if the first mbuf has much
* less data than the following.
*/
m = m0;
again:
for (;;) {
n = m->m_next;
if (n == NULL)
break;
if (n->m_len < M_TRAILINGSPACE(m)) {
bcopy(mtod(n, void *), mtod(m, char *) + m->m_len,
n->m_len);
m->m_len += n->m_len;
m->m_next = n->m_next;
m_free(n);
if (--curfrags <= maxfrags)
return m0;
} else
m = n;
}
KASSERT(maxfrags > 1,
("maxfrags %u, but normal collapse failed", maxfrags));
/*
* Collapse consecutive mbufs to a cluster.
*/
prev = &m0->m_next; /* NB: not the first mbuf */
while ((n = *prev) != NULL) {
if ((n2 = n->m_next) != NULL &&
n->m_len + n2->m_len < MCLBYTES) {
m = m_getcl(how, MT_DATA, 0);
if (m == NULL)
goto bad;
bcopy(mtod(n, void *), mtod(m, void *), n->m_len);
bcopy(mtod(n2, void *), mtod(m, char *) + n->m_len,
n2->m_len);
m->m_len = n->m_len + n2->m_len;
m->m_next = n2->m_next;
*prev = m;
m_free(n);
m_free(n2);
if (--curfrags <= maxfrags) /* +1 cl -2 mbufs */
return m0;
/*
* Still not there, try the normal collapse
* again before we allocate another cluster.
*/
goto again;
}
prev = &n->m_next;
}
/*
* No place where we can collapse to a cluster; punt.
* This can occur if, for example, you request 2 frags
* but the packet requires that both be clusters (we
* never reallocate the first mbuf to avoid moving the
* packet header).
*/
bad:
return NULL;
}
static int
ath_tx_start(struct ath_softc *sc, struct ieee80211_node *ni, struct ath_buf *bf,
struct mbuf *m0)
@ -2912,6 +2995,7 @@ ath_tx_start(struct ath_softc *sc, struct ieee80211_node *ni, struct ath_buf *bf
const HAL_RATE_TABLE *rt;
HAL_BOOL shortPreamble;
struct ath_node *an;
struct mbuf *m;
wh = mtod(m0, struct ieee80211_frame *);
iswep = wh->i_fc[1] & IEEE80211_FC1_WEP;
@ -2987,12 +3071,13 @@ ath_tx_start(struct ath_softc *sc, struct ieee80211_node *ni, struct ath_buf *bf
*/
if (bf->bf_nseg > ATH_TXDESC) { /* too many desc's, linearize */
sc->sc_stats.ast_tx_linear++;
m0 = m_defrag(m0, M_DONTWAIT);
if (m0 == NULL) {
sc->sc_stats.ast_tx_nombuf++;
m = ath_defrag(m0, M_DONTWAIT, ATH_TXDESC);
if (m == NULL) {
m_freem(m0);
sc->sc_stats.ast_tx_nombuf++;
return ENOMEM;
}
m0 = m;
error = bus_dmamap_load_mbuf_sg(sc->sc_dmat, bf->bf_dmamap, m0,
bf->bf_segs, &bf->bf_nseg,
BUS_DMA_NOWAIT);