Author: np
Date: Sat Sep 9 05:12:14 2017
New Revision: 323343
URL: https://svnweb.freebsd.org/changeset/base/323343
Log:
cxgbe(4): Fix a couple of problems in the sge_wrq data path.
- start_wrq_wr must not drain the wr_list if there are incomplete_wrs
pending. This can happen when a t4_wrq_tx runs between two
start_wrq_wr.
- commit_wrq_wr must examine the cookie's pidx and ndesc with the
queue's lock held. Otherwise there is a bad race when incomplete WRs
are being completed and commit_wrq_wr for the WR that is ahead in the
queue updates the next incomplete WR's cookie's pidx/ndesc but the
commit_wrq_wr for the second one is using stale values that it read
without the lock.
MFC after: 1 week
Sponsored by: Chelsio Communications
Modified:
head/sys/dev/cxgbe/t4_sge.c
Modified: head/sys/dev/cxgbe/t4_sge.c
==============================================================================
--- head/sys/dev/cxgbe/t4_sge.c Sat Sep 9 03:09:02 2017 (r323342)
+++ head/sys/dev/cxgbe/t4_sge.c Sat Sep 9 05:12:14 2017 (r323343)
@@ -2354,7 +2354,7 @@ start_wrq_wr(struct sge_wrq *wrq, int len16, struct wr
EQ_LOCK(eq);
- if (!STAILQ_EMPTY(&wrq->wr_list))
+ if (TAILQ_EMPTY(&wrq->incomplete_wrs) && !STAILQ_EMPTY(&wrq->wr_list))
drain_wrq_wr_list(sc, wrq);
if (!STAILQ_EMPTY(&wrq->wr_list)) {
@@ -2408,9 +2408,6 @@ commit_wrq_wr(struct sge_wrq *wrq, void *w, struct wrq
return;
}
- ndesc = cookie->ndesc; /* Can be more than SGE_MAX_WR_NDESC here. */
- pidx = cookie->pidx;
- MPASS(pidx >= 0 && pidx < eq->sidx);
if (__predict_false(w == &wrq->ss[0])) {
int n = (eq->sidx - wrq->ss_pidx) * EQ_ESIZE;
@@ -2422,6 +2419,9 @@ commit_wrq_wr(struct sge_wrq *wrq, void *w, struct wrq
wrq->tx_wrs_direct++;
EQ_LOCK(eq);
+ ndesc = cookie->ndesc; /* Can be more than SGE_MAX_WR_NDESC here. */
+ pidx = cookie->pidx;
+ MPASS(pidx >= 0 && pidx < eq->sidx);
prev = TAILQ_PREV(cookie, wrq_incomplete_wrs, link);
next = TAILQ_NEXT(cookie, link);
if (prev == NULL) {
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