Date: Thu, 8 Mar 2012 23:53:38 +0000 (UTC) From: Adrian Chadd <adrian@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r232707 - head/sys/dev/ath Message-ID: <201203082353.q28Nrc5k070154@svn.freebsd.org>
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Author: adrian Date: Thu Mar 8 23:53:38 2012 New Revision: 232707 URL: http://svn.freebsd.org/changeset/base/232707 Log: Correctly initialise the TXQ link pointer to the last descriptor in the last buffer in the list. The current behaviour (due to me, so pointy hat is firmly on my head here) was incorrect - it was setting the link pointer to the last descriptor of the _first_ buffer in the TXQ. Instead, it should have set it to the last descriptor in the _last_ buffer in the TXQ. This showed up as occasional TX stalls with frames in the TXQ but no TX progress being made. Further inspection showed the TXQ looked like it contained multiple "lists" of frames - there'd be a list of correct frames, then a NULL link pointer, but there'd be a next buffer in the list. Since this code is only called upon an interface reset, it's likely this only began showing up when I started doing stress testing in environments which annoy the radios enough to cause lockups. I've not yet any TX stalls with this patch applied. PR: kern/165866 Modified: head/sys/dev/ath/if_ath_tx.c Modified: head/sys/dev/ath/if_ath_tx.c ============================================================================== --- head/sys/dev/ath/if_ath_tx.c Thu Mar 8 23:52:22 2012 (r232706) +++ head/sys/dev/ath/if_ath_tx.c Thu Mar 8 23:53:38 2012 (r232707) @@ -623,19 +623,22 @@ void ath_txq_restart_dma(struct ath_softc *sc, struct ath_txq *txq) { struct ath_hal *ah = sc->sc_ah; - struct ath_buf *bf; + struct ath_buf *bf, *bf_last; ATH_TXQ_LOCK_ASSERT(txq); /* This is always going to be cleared, empty or not */ txq->axq_flags &= ~ATH_TXQ_PUTPENDING; + /* XXX make this ATH_TXQ_FIRST */ bf = TAILQ_FIRST(&txq->axq_q); + bf_last = ATH_TXQ_LAST(txq, axq_q_s); + if (bf == NULL) return; ath_hal_puttxbuf(ah, txq->axq_qnum, bf->bf_daddr); - txq->axq_link = &bf->bf_lastds->ds_link; + txq->axq_link = &bf_last->bf_lastds->ds_link; ath_hal_txstart(ah, txq->axq_qnum); }
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