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Code Issues Releases Activity

iflib: fix isc_rxd_flush call in netmap_fl_refill()

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The semantic of the pidx argument of isc_rxd_flush() is the
last valid index of in the free list, rather than the next
index to be published. However, netmap was still using the
old convention. While there, also refactor the netmap_fl_refill()
to simplify a little bit and add an assertion.

MFC after:	2 weeks
This commit is contained in:
Vincenzo Maffione 2020-08-24 11:44:20 +00:00
parent ebae797c82
commit de5b46107c
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=364655
1 changed files with 28 additions and 15 deletions
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43
sys/net/iflib.c
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@ -757,7 +757,7 @@ iflib_num_tx_descs(if_ctx_t ctx)
MODULE_DEPEND(iflib, netmap, 1, 1, 1);
static int netmap_fl_refill(iflib_rxq_t rxq, struct netmap_kring *kring, uint32_t nm_i, bool init);
static int netmap_fl_refill(iflib_rxq_t rxq, struct netmap_kring *kring, bool init);
/*
* device-specific sysctl variables:
@ -828,33 +828,43 @@ iflib_netmap_register(struct netmap_adapter *na, int onoff)
}
static int
netmap_fl_refill(iflib_rxq_t rxq, struct netmap_kring *kring, uint32_t nm_i, bool init)
netmap_fl_refill(iflib_rxq_t rxq, struct netmap_kring *kring, bool init)
{
struct netmap_adapter *na = kring->na;
u_int const lim = kring->nkr_num_slots - 1;
u_int head = kring->rhead;
u_int nm_i = kring->nr_hwcur;
struct netmap_ring *ring = kring->ring;
bus_dmamap_t *map;
struct if_rxd_update iru;
if_ctx_t ctx = rxq->ifr_ctx;
iflib_fl_t fl = &rxq->ifr_fl[0];
uint32_t nic_i_first, nic_i;
u_int nic_i_first, nic_i;
int i;
#if IFLIB_DEBUG_COUNTERS
int rf_count = 0;
#endif
if (nm_i == head && __predict_true(!init))
/*
* Netmap requires that we leave (at least) one free slot
* in the ring, so that it can distinguish between an empty
* ring (nr_hwcur == nr_hwtail, i.e. all the buffers owned by the
* user) and a full ring (nr_hwtail == (nr_hwcur - 1) mod N, i.e.
* all the buffers owned by the kernel).
* We thus set head (the refill limit) to nr_hwcur - 1
* at initialization. The rest of the code will then make sure
* than nr_hwtail never overcomes nr_hwcur.
*/
if (__predict_false(init)) {
head = nm_prev(nm_i, lim);
} else if (nm_i == head) {
/* Nothing to do. We can leave early. */
return (0);
}
iru_init(&iru, rxq, 0 /* flid */);
map = fl->ifl_sds.ifsd_map;
nic_i = netmap_idx_k2n(kring, nm_i);
/*
* IMPORTANT: we must leave one free slot in the ring,
* so move head back by one unit
*/
head = nm_prev(head, lim);
DBG_COUNTER_INC(fl_refills);
while (nm_i != head) {
#if IFLIB_DEBUG_COUNTERS
@ -895,9 +905,13 @@ netmap_fl_refill(iflib_rxq_t rxq, struct netmap_kring *kring, uint32_t nm_i, boo
}
kring->nr_hwcur = head;
/* The pidx argument of isc_rxd_flush() is the index of the last valid
* slot in the free list ring. We need therefore to decrement nic_i,
* similarly to what happens in iflib_fl_refill() for ifl_pidx. */
bus_dmamap_sync(fl->ifl_ifdi->idi_tag, fl->ifl_ifdi->idi_map,
BUS_DMASYNC_PREREAD | BUS_DMASYNC_PREWRITE);
ctx->isc_rxd_flush(ctx->ifc_softc, rxq->ifr_id, fl->ifl_id, nic_i);
ctx->isc_rxd_flush(ctx->ifc_softc, rxq->ifr_id, fl->ifl_id,
nm_prev(nic_i, lim));
DBG_COUNTER_INC(rxd_flush);
return (0);
@ -1127,6 +1141,7 @@ iflib_netmap_rxsync(struct netmap_kring *kring, int flags)
nic_i = fl->ifl_cidx;
nm_i = netmap_idx_n2k(kring, nic_i);
MPASS(nm_i == kring->nr_hwtail);
for (n = 0; avail > 0 && nm_i != hwtail_lim; n++, avail--) {
rxd_info_zero(&ri);
ri.iri_frags = rxq->ifr_frags;
@ -1165,9 +1180,9 @@ iflib_netmap_rxsync(struct netmap_kring *kring, int flags)
* nic_i is the index in the NIC ring, and
* nm_i == (nic_i + kring->nkr_hwofs) % ring_size
*/
nm_i = kring->nr_hwcur;
netmap_fl_refill(rxq, kring, false);
return (netmap_fl_refill(rxq, kring, nm_i, false));
return (0);
}
static void
@ -1239,14 +1254,12 @@ iflib_netmap_rxq_init(if_ctx_t ctx, iflib_rxq_t rxq)
struct netmap_adapter *na = NA(ctx->ifc_ifp);
struct netmap_kring *kring;
struct netmap_slot *slot;
uint32_t nm_i;
slot = netmap_reset(na, NR_RX, rxq->ifr_id, 0);
if (slot == NULL)
return (0);
kring = na->rx_rings[rxq->ifr_id];
nm_i = netmap_idx_n2k(kring, 0);
netmap_fl_refill(rxq, kring, nm_i, true);
netmap_fl_refill(rxq, kring, true);
return (1);
}