svn commit: r367917 - head/sys/dev/cxgbe

[Navdeep Parhar]

Author: np
Date: Sat Nov 21 03:27:32 2020
New Revision: 367917
URL: https://svnweb.freebsd.org/changeset/base/367917

Log:
  cxgbe(4): Catch up with in-flight netmap rx before destroying queues.
  
  The netmap application using the driver is responsible for replenishing
  the receive freelists and they may be totally depleted when the
  application exits.  Packets in flight, if any, might block the pipeline
  in case there aren't enough buffers left in the freelist.  Avoid this by
  filling up the freelists with a driver allocated buffer.
  
  MFC after:	1 week
  Sponsored by:	Chelsio Communications

Modified:
  head/sys/dev/cxgbe/adapter.h
  head/sys/dev/cxgbe/t4_netmap.c

Modified: head/sys/dev/cxgbe/adapter.h
==============================================================================
--- head/sys/dev/cxgbe/adapter.h	Sat Nov 21 00:53:31 2020	(r367916)
+++ head/sys/dev/cxgbe/adapter.h	Sat Nov 21 03:27:32 2020	(r367917)
@@ -749,6 +749,9 @@ struct sge_nm_rxq {
 	bus_dma_tag_t fl_desc_tag;
 	bus_dmamap_t fl_desc_map;
 	bus_addr_t fl_ba;
+
+	void *bb;		/* bit bucket for packets with nowhere to go. */
+	uma_zone_t bb_zone;
 };
 
 #define INVALID_NM_TXQ_CNTXT_ID ((u_int)(-1))

Modified: head/sys/dev/cxgbe/t4_netmap.c
==============================================================================
--- head/sys/dev/cxgbe/t4_netmap.c	Sat Nov 21 00:53:31 2020	(r367916)
+++ head/sys/dev/cxgbe/t4_netmap.c	Sat Nov 21 03:27:32 2020	(r367917)
@@ -42,6 +42,8 @@ __FBSDID("$FreeBSD$");
 #include <sys/socket.h>
 #include <sys/sockio.h>
 #include <machine/bus.h>
+#include <vm/vm.h>
+#include <vm/pmap.h>
 #include <net/ethernet.h>
 #include <net/if.h>
 #include <net/if_media.h>
@@ -586,6 +588,8 @@ cxgbe_netmap_on(struct adapter *sc, struct vi_info *vi
 
 		alloc_nm_rxq_hwq(vi, nm_rxq, tnl_cong(vi->pi, nm_cong_drop));
 		nm_rxq->fl_hwidx = hwidx;
+		nm_rxq->bb_zone = rxb->zone;
+		nm_rxq->bb = uma_zalloc(nm_rxq->bb_zone, M_WAITOK);
 		slot = netmap_reset(na, NR_RX, i, 0);
 		MPASS(slot != NULL);	/* XXXNM: error check, not assert */
 
@@ -628,6 +632,31 @@ cxgbe_netmap_on(struct adapter *sc, struct vi_info *vi
 	return (cxgbe_netmap_rss(sc, vi, ifp, na));
 }
 
+static void
+flush_nm_rxq(struct adapter *sc, struct vi_info *vi, struct sge_nm_rxq *nm_rxq)
+{
+	int i, n;
+	u_int fl_pidx, fl_pidx_target, hw_cidx_desc;
+	const uint64_t ba = pmap_kextract((vm_offset_t)nm_rxq->bb);
+
+	hw_cidx_desc = nm_rxq->fl_cidx / 8;
+	if (hw_cidx_desc == 0)
+		fl_pidx_target = nm_rxq->fl_sidx2 - 8;
+	else
+		fl_pidx_target = (hw_cidx_desc - 1) * 8;
+	MPASS((fl_pidx_target & 7) == 0);
+
+	fl_pidx = nm_rxq->fl_pidx;
+	MPASS((fl_pidx & 7) == 0);
+	for (n = 0; fl_pidx != fl_pidx_target; n++) {
+		for (i = 0; i < 8; i++, fl_pidx++)
+			nm_rxq->fl_desc[fl_pidx] = htobe64(ba | nm_rxq->fl_hwidx);
+		if (__predict_false(fl_pidx == nm_rxq->fl_sidx2))
+			fl_pidx = 0;
+	}
+	t4_write_reg(sc, sc->sge_kdoorbell_reg, nm_rxq->fl_db_val | V_PIDX(n));
+}
+
 static int
 cxgbe_netmap_off(struct adapter *sc, struct vi_info *vi, struct ifnet *ifp,
     struct netmap_adapter *na)
@@ -652,6 +681,23 @@ cxgbe_netmap_off(struct adapter *sc, struct vi_info *v
 	if (rc != 0)
 		return (rc);	/* error message logged already. */
 
+	/*
+	 * First pass over the rx queues to make sure they're all caught up.
+	 *
+	 * The freelists could be out of buffers and we may need to arrange
+	 * things so that any packets still in flight (after TP's cong_drop
+	 * logic but not yet DMA'd) have somewhere to go and do not block the
+	 * pipeline.  Do this before trying to free any queue.
+	 */
+	for_each_nm_rxq(vi, i, nm_rxq) {
+		nm_state = atomic_load_int(&nm_rxq->nm_state);
+		kring = na->rx_rings[nm_rxq->nid];
+		if (nm_state == NM_OFF || !nm_kring_pending_off(kring))
+			continue;
+		MPASS(nm_rxq->iq_cntxt_id != INVALID_NM_RXQ_CNTXT_ID);
+		flush_nm_rxq(sc, vi, nm_rxq);
+	}
+
 	for_each_nm_txq(vi, i, nm_txq) {
 		struct sge_qstat *spg = (void *)&nm_txq->desc[nm_txq->sidx];
 
@@ -688,6 +734,8 @@ cxgbe_netmap_off(struct adapter *sc, struct vi_info *v
 			pause("nmst", 1);
 
 		free_nm_rxq_hwq(vi, nm_rxq);
+		uma_zfree(nm_rxq->bb_zone, nm_rxq->bb);
+		nm_rxq->bb = NULL;
 
 		/* XXX: netmap, not the driver, should do this. */
 		kring->rhead = kring->rcur = kring->nr_hwcur = 0;