Author: adrian
Date: Tue Nov 8 21:13:05 2011
New Revision: 227359
URL: http://svn.freebsd.org/changeset/base/227359
Log:
Change ath_buf allocation to:
* Immediately return NULL if a buffer isn't available;
* Track the "buffers not available" count;
* Clear some fields used for tx aggregation;
* Add ath_buf_clone() which clones the majority of buffer state.
This is needed when retransmission of a "busy" buffer is required.
Sponsored by: Hobnob, Inc.
Modified:
head/sys/dev/ath/if_ath.c
head/sys/dev/ath/if_ath_misc.h
Modified: head/sys/dev/ath/if_ath.c
==============================================================================
--- head/sys/dev/ath/if_ath.c Tue Nov 8 21:06:36 2011 (r227358)
+++ head/sys/dev/ath/if_ath.c Tue Nov 8 21:13:05 2011 (r227359)
@@ -1890,18 +1890,89 @@ _ath_getbuf_locked(struct ath_softc *sc)
ATH_TXBUF_LOCK_ASSERT(sc);
bf = TAILQ_FIRST(&sc->sc_txbuf);
+ if (bf == NULL) {
+ sc->sc_stats.ast_tx_getnobuf++;
+ } else {
+ if (bf->bf_flags & ATH_BUF_BUSY) {
+ sc->sc_stats.ast_tx_getbusybuf++;
+ bf = NULL;
+ }
+ }
+
if (bf != NULL && (bf->bf_flags & ATH_BUF_BUSY) == 0)
TAILQ_REMOVE(&sc->sc_txbuf, bf, bf_list);
else
bf = NULL;
+
if (bf == NULL) {
DPRINTF(sc, ATH_DEBUG_XMIT, "%s: %s\n", __func__,
TAILQ_FIRST(&sc->sc_txbuf) == NULL ?
"out of xmit buffers" : "xmit buffer busy");
+ return NULL;
}
+
+ /* Valid bf here; clear some basic fields */
+ bf->bf_next = NULL; /* XXX just to be sure */
+ bf->bf_last = NULL; /* XXX again, just to be sure */
+ bf->bf_comp = NULL; /* XXX again, just to be sure */
+ bzero(&bf->bf_state, sizeof(bf->bf_state));
+
return bf;
}
+/*
+ * When retrying a software frame, buffers marked ATH_BUF_BUSY
+ * can't be thrown back on the queue as they could still be
+ * in use by the hardware.
+ *
+ * This duplicates the buffer, or returns NULL.
+ *
+ * The descriptor is also copied but the link pointers and
+ * the DMA segments aren't copied; this frame should thus
+ * be again passed through the descriptor setup/chain routines
+ * so the link is correct.
+ *
+ * The caller must free the buffer using ath_freebuf().
+ *
+ * XXX TODO: this call shouldn't fail as it'll cause packet loss
+ * XXX in the TX pathway when retries are needed.
+ * XXX Figure out how to keep some buffers free, or factor the
+ * XXX number of busy buffers into the xmit path (ath_start())
+ * XXX so we don't over-commit.
+ */
+struct ath_buf *
+ath_buf_clone(struct ath_softc *sc, const struct ath_buf *bf)
+{
+ struct ath_buf *tbf;
+
+ tbf = ath_getbuf(sc);
+ if (tbf == NULL)
+ return NULL; /* XXX failure? Why? */
+
+ /* Copy basics */
+ tbf->bf_next = NULL;
+ tbf->bf_nseg = bf->bf_nseg;
+ tbf->bf_txflags = bf->bf_txflags;
+ tbf->bf_flags = bf->bf_flags & ~ATH_BUF_BUSY;
+ tbf->bf_status = bf->bf_status;
+ tbf->bf_m = bf->bf_m;
+ tbf->bf_node = bf->bf_node;
+ /* will be setup by the chain/setup function */
+ tbf->bf_lastds = NULL;
+ /* for now, last == self */
+ tbf->bf_last = tbf;
+ tbf->bf_comp = bf->bf_comp;
+
+ /* NOTE: DMA segments will be setup by the setup/chain functions */
+
+ /* The caller has to re-init the descriptor + links */
+
+ /* Copy state */
+ memcpy(&tbf->bf_state, &bf->bf_state, sizeof(bf->bf_state));
+
+ return tbf;
+}
+
struct ath_buf *
ath_getbuf(struct ath_softc *sc)
{
Modified: head/sys/dev/ath/if_ath_misc.h
==============================================================================
--- head/sys/dev/ath/if_ath_misc.h Tue Nov 8 21:06:36 2011
(r227358)
+++ head/sys/dev/ath/if_ath_misc.h Tue Nov 8 21:13:05 2011
(r227359)
@@ -52,6 +52,8 @@ extern int ath_tx_findrix(const struct a
extern struct ath_buf * ath_getbuf(struct ath_softc *sc);
extern struct ath_buf * _ath_getbuf_locked(struct ath_softc *sc);
+extern struct ath_buf * ath_buf_clone(struct ath_softc *sc,
+ const struct ath_buf *bf);
extern int ath_reset(struct ifnet *, ATH_RESET_TYPE);
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