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cxgbe(4): Catch up with in-flight netmap rx before destroying queues.

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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
This commit is contained in:
Navdeep Parhar 2020-11-21 03:27:32 +00:00
parent 9a201fad1d
commit b3718e2d7e
2 changed files with 51 additions and 0 deletions
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3
sys/dev/cxgbe/adapter.h
View File

@ -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))

48
sys/dev/cxgbe/t4_netmap.c
View File

@ -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, struct ifnet *ifp,
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, struct ifnet *ifp,
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 *vi, struct ifnet *ifp,
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 *vi, struct ifnet *ifp,
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;