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Date:      Thu, 20 Feb 2020 07:12:43 +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: r358156 - head/sys/dev/ath
Message-ID:  <202002200712.01K7ChWl095993@repo.freebsd.org>
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Author: adrian
Date: Thu Feb 20 07:12:43 2020
New Revision: 358156
URL: https://svnweb.freebsd.org/changeset/base/358156

Log:
  [ath] Attempt to fix epoch handling.
  
  The epoch stuff with taskqueues works fine if the driver never calls
  the receive path in other contexts, but this driver does.  If there was
  a chip reset during active receive then part of the reset will call
  the receive path to flush out any active packets before reinitialising
  the receive queue and that needs to be done with the epoch held.
  
  So:
  
  * make the receive task a normal task again
  * explicitly call epoch enter/exit around the legacy and newer DMA
    receive paths
  * add a couple of epoch asserts to ensure that the receive packet
    path itself is called with epoch held.
  
  This fixes it on my Atom eeepc laptop (circa 2010!) that I did
  all of my initial 802.11n work in this driver and net80211.
  
  Tested:
  
  * AR9285, STA mode
  
  TODO:
  
  * Test on EDMA chipset (AR9380)
  * Test in AP/adhoc modes, just to be sure (eg for beacon
    receive processing in particular.)

Modified:
  head/sys/dev/ath/if_ath.c
  head/sys/dev/ath/if_ath_rx.c
  head/sys/dev/ath/if_ath_rx_edma.c

Modified: head/sys/dev/ath/if_ath.c
==============================================================================
--- head/sys/dev/ath/if_ath.c	Thu Feb 20 06:45:51 2020	(r358155)
+++ head/sys/dev/ath/if_ath.c	Thu Feb 20 07:12:43 2020	(r358156)
@@ -760,7 +760,7 @@ ath_attach(u_int16_t devid, struct ath_softc *sc)
 	taskqueue_start_threads(&sc->sc_tq, 1, PI_NET, "%s taskq",
 	    device_get_nameunit(sc->sc_dev));
 
-	NET_TASK_INIT(&sc->sc_rxtask, 0, sc->sc_rx.recv_tasklet, sc);
+	TASK_INIT(&sc->sc_rxtask, 0, sc->sc_rx.recv_tasklet, sc);
 	TASK_INIT(&sc->sc_bmisstask, 0, ath_bmiss_proc, sc);
 	TASK_INIT(&sc->sc_bstucktask,0, ath_bstuck_proc, sc);
 	TASK_INIT(&sc->sc_resettask,0, ath_reset_proc, sc);

Modified: head/sys/dev/ath/if_ath_rx.c
==============================================================================
--- head/sys/dev/ath/if_ath_rx.c	Thu Feb 20 06:45:51 2020	(r358155)
+++ head/sys/dev/ath/if_ath_rx.c	Thu Feb 20 07:12:43 2020	(r358156)
@@ -656,6 +656,8 @@ ath_rx_pkt(struct ath_softc *sc, struct ath_rx_status 
 	int is_good = 0;
 	struct ath_rx_edma *re = &sc->sc_rxedma[qtype];
 
+	NET_EPOCH_ASSERT();
+
 	/*
 	 * Calculate the correct 64 bit TSF given
 	 * the TSF64 register value and rs_tstamp.
@@ -1074,6 +1076,8 @@ ath_rx_proc(struct ath_softc *sc, int resched)
 	int kickpcu = 0;
 	int ret;
 
+	NET_EPOCH_ASSERT();
+
 	/* XXX we must not hold the ATH_LOCK here */
 	ATH_UNLOCK_ASSERT(sc);
 	ATH_PCU_UNLOCK_ASSERT(sc);
@@ -1293,6 +1297,7 @@ static void
 ath_legacy_rx_tasklet(void *arg, int npending)
 {
 	struct ath_softc *sc = arg;
+	struct epoch_tracker et;
 
 	ATH_KTR(sc, ATH_KTR_RXPROC, 1, "ath_rx_proc: pending=%d", npending);
 	DPRINTF(sc, ATH_DEBUG_RX_PROC, "%s: pending %u\n", __func__, npending);
@@ -1305,14 +1310,18 @@ ath_legacy_rx_tasklet(void *arg, int npending)
 	}
 	ATH_PCU_UNLOCK(sc);
 
+	NET_EPOCH_ENTER(et);
 	ath_rx_proc(sc, 1);
+	NET_EPOCH_EXIT(et);
 }
 
 static void
 ath_legacy_flushrecv(struct ath_softc *sc)
 {
-
+	struct epoch_tracker et;
+	NET_EPOCH_ENTER(et);
 	ath_rx_proc(sc, 0);
+	NET_EPOCH_EXIT(et);
 }
 
 static void

Modified: head/sys/dev/ath/if_ath_rx_edma.c
==============================================================================
--- head/sys/dev/ath/if_ath_rx_edma.c	Thu Feb 20 06:45:51 2020	(r358155)
+++ head/sys/dev/ath/if_ath_rx_edma.c	Thu Feb 20 07:12:43 2020	(r358156)
@@ -521,6 +521,7 @@ ath_edma_recv_proc_deferred_queue(struct ath_softc *sc
 	int16_t nf;
 	ath_bufhead rxlist;
 	struct mbuf *m;
+	struct epoch_tracker et;
 
 	TAILQ_INIT(&rxlist);
 
@@ -537,6 +538,8 @@ ath_edma_recv_proc_deferred_queue(struct ath_softc *sc
 	TAILQ_CONCAT(&rxlist, &sc->sc_rx_rxlist[qtype], bf_list);
 	ATH_RX_UNLOCK(sc);
 
+	NET_EPOCH_ENTER(et);
+
 	/* Handle the completed descriptors */
 	/*
 	 * XXX is this SAFE call needed? The ath_buf entries
@@ -560,6 +563,7 @@ ath_edma_recv_proc_deferred_queue(struct ath_softc *sc
 	if (ngood) {
 		sc->sc_lastrx = tsf;
 	}
+	NET_EPOCH_EXIT(et);
 
 	ATH_KTR(sc, ATH_KTR_INTERRUPTS, 1,
 	    "ath edma rx deferred proc: ngood=%d\n",

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