svn commit: r322981 - head/sys/dev/ntb

[Alexander Motin]

Author: mav
Date: Mon Aug 28 20:00:21 2017
New Revision: 322981
URL: https://svnweb.freebsd.org/changeset/base/322981

Log:
  Mask doorbells while processing them.
  
  This fixes interrupt storms on hardware using legacy level-triggered
  interrupts, since doorbell processing could take time after interrupt
  handler completion, that triggered extra interrupts in a loop.
  
  MFC after:	2 weeks
  Sponsored by:	iXsystems, Inc.

Modified:
  head/sys/dev/ntb/ntb_transport.c

Modified: head/sys/dev/ntb/ntb_transport.c
==============================================================================
--- head/sys/dev/ntb/ntb_transport.c	Mon Aug 28 19:52:57 2017	(r322980)
+++ head/sys/dev/ntb/ntb_transport.c	Mon Aug 28 20:00:21 2017	(r322981)
@@ -835,6 +835,7 @@ static void
 ntb_transport_rxc_db(void *arg, int pending __unused)
 {
 	struct ntb_transport_qp *qp = arg;
+	uint64_t qp_mask = 1ull << qp->qp_num;
 	int rc;
 
 	CTR0(KTR_NTB, "RX: transport_rx");
@@ -843,11 +844,13 @@ again:
 		;
 	CTR1(KTR_NTB, "RX: process_rxc returned %d", rc);
 
-	if ((ntb_db_read(qp->dev) & (1ull << qp->qp_num)) != 0) {
+	if ((ntb_db_read(qp->dev) & qp_mask) != 0) {
 		/* If db is set, clear it and check queue once more. */
-		ntb_db_clear(qp->dev, 1ull << qp->qp_num);
+		ntb_db_clear(qp->dev, qp_mask);
 		goto again;
 	}
+	if (qp->link_is_up)
+		ntb_db_clear_mask(qp->dev, qp_mask);
 }
 
 static int
@@ -1009,6 +1012,8 @@ ntb_transport_doorbell_callback(void *data, uint32_t v
 	vec_mask &= nt->qp_bitmap;
 	if ((vec_mask & (vec_mask - 1)) != 0)
 		vec_mask &= ntb_db_read(nt->dev);
+	if (vec_mask != 0)
+		ntb_db_set_mask(nt->dev, vec_mask);
 	while (vec_mask != 0) {
 		qp_num = ffsll(vec_mask) - 1;