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freebsd-nq/sys/dev/ath/if_ath_misc.h
Adrian Chadd c5239edb98 Implement frame (data) transmission using if_transmit(), rather than 
if_start().

This removes the overlapping data path TX from occuring, which
solves quite a number of the potential TX queue races in ath(4).
It doesn't fix the net80211 layer TX queue races and it doesn't
fix the raw TX path yet, but it's an important step towards this.

This hasn't dropped the TX performance in my testing; primarily
because now the TX path can quickly queue frames and continue
along processing.

This involves a few rather deep changes:

* Use the ath_buf as a queue placeholder for now, as we need to be
  able to support queuing a list of mbufs (ie, when transmitting
  fragments) and m_nextpkt can't be used here (because it's what is
  joining the fragments together)

* if_transmit() now simply allocates the ath_buf and queues it to
  a driver TX staging queue.

* TX is now moved into a taskqueue function.

* The TX taskqueue function now dequeues and transmits frames.

* Fragments are handled correctly here - as the current API passes
  the fragment list as one mbuf list (joined with m_nextpkt) through
  to the driver if_transmit().

* For the couple of places where ath_start() may be called (mostly
  from net80211 when starting the VAP up again), just reimplement
  it using the new enqueue and taskqueue methods.

What I don't like (about this work and the TX code in general):

* I'm using the same lock for the staging TX queue management and the
  actual TX.  This isn't required; I'm just being slack.

* I haven't yet moved TX to a separate taskqueue (but the taskqueue is
  created); it's easy enough to do this later if necessary.  I just need
  to make sure it's a higher priority queue, so TX has the same
  behaviour as it used to (where it would preempt existing RX..)

* I need to re-review the TX path a little more and make sure that
  ieee80211_node_*() functions aren't called within the TX lock.
  When queueing, I should just push failed frames into a queue and
  when I'm wrapping up the TX code, unlock the TX lock and
  call ieee80211_node_free() on each.

* It would be nice if I could hold the TX lock for the entire
  TX and TX completion, rather than this release/re-acquire behaviour.
  But that requires that I shuffle around the TX completion code
  to handle actual ath_buf free and net80211 callback/free outside
  of the TX lock.  That's one of my next projects.

* the ic_raw_xmit() path doesn't use this yet - so it still has
  sequencing problems with parallel, overlapping calls to the
  data path.  I'll fix this later.

Tested:

* Hostap - AR9280, AR9220
* STA - AR5212, AR9280, AR5416
2013-01-15 18:01:23 +00:00

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/*-
* Copyright (c) 2002-2009 Sam Leffler, Errno Consulting
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer,
* without modification.
* 2. Redistributions in binary form must reproduce at minimum a disclaimer
* similar to the "NO WARRANTY" disclaimer below ("Disclaimer") and any
* redistribution must be conditioned upon including a substantially
* similar Disclaimer requirement for further binary redistribution.
*
* NO WARRANTY
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF NONINFRINGEMENT, MERCHANTIBILITY
* AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL
* THE COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR SPECIAL, EXEMPLARY,
* OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER
* IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
* THE POSSIBILITY OF SUCH DAMAGES.
*
* $FreeBSD$
*/
#ifndef __IF_ATH_MISC_H__
#define __IF_ATH_MISC_H__
/*
* This is where definitions for "public things" in if_ath.c
* will go for the time being.
*
* Anything in here should eventually be moved out of if_ath.c
* and into something else.
*/
/* unaligned little endian access */
#define LE_READ_2(p) \
((u_int16_t) \
((((u_int8_t *)(p))[0] ) | (((u_int8_t *)(p))[1] << 8)))
#define LE_READ_4(p) \
((u_int32_t) \
((((u_int8_t *)(p))[0] ) | (((u_int8_t *)(p))[1] << 8) | \
(((u_int8_t *)(p))[2] << 16) | (((u_int8_t *)(p))[3] << 24)))
extern int ath_rxbuf;
extern int ath_txbuf;
extern int ath_txbuf_mgmt;
extern int ath_tx_findrix(const struct ath_softc *sc, uint8_t rate);
extern struct ath_buf * ath_getbuf(struct ath_softc *sc,
ath_buf_type_t btype);
extern struct ath_buf * _ath_getbuf_locked(struct ath_softc *sc,
ath_buf_type_t btype);
extern struct ath_buf * ath_buf_clone(struct ath_softc *sc,
const struct ath_buf *bf);
/* XXX change this to NULL the buffer pointer? */
extern void ath_freebuf(struct ath_softc *sc, struct ath_buf *bf);
extern void ath_returnbuf_head(struct ath_softc *sc, struct ath_buf *bf);
extern void ath_returnbuf_tail(struct ath_softc *sc, struct ath_buf *bf);
extern int ath_reset(struct ifnet *, ATH_RESET_TYPE);
extern void ath_tx_default_comp(struct ath_softc *sc, struct ath_buf *bf,
int fail);
extern void ath_tx_update_ratectrl(struct ath_softc *sc,
struct ieee80211_node *ni, struct ath_rc_series *rc,
struct ath_tx_status *ts, int frmlen, int nframes, int nbad);
extern void ath_tx_freebuf(struct ath_softc *sc, struct ath_buf *bf,
int status);
extern void ath_txqmove(struct ath_txq *dst, struct ath_txq *src);
extern void ath_mode_init(struct ath_softc *sc);
extern void ath_setdefantenna(struct ath_softc *sc, u_int antenna);
extern void ath_setslottime(struct ath_softc *sc);
extern int ath_descdma_alloc_desc(struct ath_softc *sc,
struct ath_descdma *dd, ath_bufhead *head, const char *name,
int ds_size, int ndesc);
extern int ath_descdma_setup(struct ath_softc *sc, struct ath_descdma *dd,
ath_bufhead *head, const char *name, int ds_size, int nbuf,
int ndesc);
extern int ath_descdma_setup_rx_edma(struct ath_softc *sc,
struct ath_descdma *dd, ath_bufhead *head, const char *name,
int nbuf, int desclen);
extern void ath_descdma_cleanup(struct ath_softc *sc,
struct ath_descdma *dd, ath_bufhead *head);
extern void ath_legacy_attach_comp_func(struct ath_softc *sc);
extern void ath_tx_draintxq(struct ath_softc *sc, struct ath_txq *txq);
extern void ath_legacy_tx_drain(struct ath_softc *sc,
ATH_RESET_TYPE reset_type);
extern void ath_tx_process_buf_completion(struct ath_softc *sc,
struct ath_txq *txq, struct ath_tx_status *ts, struct ath_buf *bf);
extern int ath_stoptxdma(struct ath_softc *sc);
extern void ath_tx_update_tim(struct ath_softc *sc,
struct ieee80211_node *ni, int enable);
/*
* This is only here so that the RX proc function can call it.
* It's very likely that the "start TX after RX" call should be
* done via something in if_ath.c, moving "rx tasklet" into
* if_ath.c and do the ath_start() call there. Once that's done,
* we can kill this.
*/
extern void ath_start(struct ifnet *ifp);
extern void ath_start_task(void *arg, int npending);
static inline void
ath_tx_kick(struct ath_softc *sc)
{
/* XXX eventually try sc_tx_tq? */
taskqueue_enqueue(sc->sc_tq, &sc->sc_txpkttask);
}
#endif
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