Fix first-packet completion

The first packet after the ring is initialized was never
completed as isc_txd_credits_update() would not include it in the
count of completed packets. This caused netmap to never complete
a batch. See PR 233022 for more details.

PR:		233022
Reported by:	lev
Reviewed by:	lev
MFC after:	3 days
Sponsored by:	Limelight Networks
Differential Revision:	https://reviews.freebsd.org/D17931
This commit is contained in:
Stephen Hurd 2018-11-09 22:18:43 +00:00
parent fe03ca08a6
commit cf49cdd5a3
Notes: svn2git 2020-12-20 02:59:44 +00:00
svn path=/head/; revision=340310
2 changed files with 12 additions and 0 deletions

View File

@ -458,7 +458,13 @@ em_isc_txd_credits_update(void *arg, uint16_t txqid, bool clear)
ntxd = scctx->isc_ntxd[0];
do {
delta = (int32_t)cur - (int32_t)prev;
/*
* XXX This appears to be a hack for first-packet.
* A correct fix would prevent prev == cur in the first place.
*/
MPASS(prev == 0 || delta != 0);
if (prev == 0 && cur == 0)
delta += 1;
if (delta < 0)
delta += ntxd;
DPRINTF(iflib_get_dev(adapter->ctx),

View File

@ -333,7 +333,13 @@ igb_isc_txd_credits_update(void *arg, uint16_t txqid, bool clear)
ntxd = scctx->isc_ntxd[0];
do {
delta = (int32_t)cur - (int32_t)prev;
/*
* XXX This appears to be a hack for first-packet.
* A correct fix would prevent prev == cur in the first place.
*/
MPASS(prev == 0 || delta != 0);
if (prev == 0 && cur == 0)
delta += 1;
if (delta < 0)
delta += ntxd;