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From: "Conrad E. Meyer" <cem@FreeBSD.org>
Date: Sat, 13 Feb 2016 02:55:45 +0000 (UTC)
To: src-committers@freebsd.org, svn-src-all@freebsd.org,
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Subject: svn commit: r295588 - head/sys/dev/ioat
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Author: cem
Date: Sat Feb 13 02:55:45 2016
New Revision: 295588
URL: https://svnweb.freebsd.org/changeset/base/295588

Log:
  ioat(4): Recheck status register on zero-descriptor wakeups
  
  Errors that halt the channel don't necessarily result in a completion
  update, apparently.
  
  Sponsored by:	EMC / Isilon Storage Division

Modified:
  head/sys/dev/ioat/ioat.c

Modified: head/sys/dev/ioat/ioat.c
==============================================================================
--- head/sys/dev/ioat/ioat.c	Sat Feb 13 00:28:48 2016	(r295587)
+++ head/sys/dev/ioat/ioat.c	Sat Feb 13 02:55:45 2016	(r295588)
@@ -630,8 +630,14 @@ ioat_process_events(struct ioat_softc *i
 
 	CTR0(KTR_IOAT, __func__);
 
-	if (status == ioat->last_seen)
+	if (status == ioat->last_seen) {
+		/*
+		 * If we landed in process_events and nothing has been
+		 * completed, check for a timeout due to channel halt.
+		 */
+		comp_update = ioat_get_chansts(ioat);
 		goto out;
+	}
 
 	while (1) {
 		desc = ioat_get_ring_entry(ioat, ioat->tail);
@@ -661,8 +667,10 @@ out:
 	ioat_write_chanctrl(ioat, IOAT_CHANCTRL_RUN);
 	mtx_unlock(&ioat->cleanup_lock);
 
-	ioat_putn(ioat, completed, IOAT_ACTIVE_DESCR_REF);
-	wakeup(&ioat->tail);
+	if (completed != 0) {
+		ioat_putn(ioat, completed, IOAT_ACTIVE_DESCR_REF);
+		wakeup(&ioat->tail);
+	}
 
 	if (!is_ioat_halted(comp_update))
 		return;