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changeset 10667:bc413e63c72c

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6277113 kstat qlen == 0 panic during completion or mirrored write
author Ray Hassan <Ray.Hassan@Sun.COM>
date Mon, 28 Sep 2009 16:13:05 +0100
parents 48f9827bb5cf
children e0d0c98c8bae
files usr/src/uts/common/io/lvm/md/md_subr.c
diffstat 1 files changed, 14 insertions(+), 2 deletions(-) [+]
line wrap: on
line diff
--- a/usr/src/uts/common/io/lvm/md/md_subr.c	Mon Sep 28 07:34:34 2009 -0700
+++ b/usr/src/uts/common/io/lvm/md/md_subr.c	Mon Sep 28 16:13:05 2009 +0100
@@ -1126,8 +1126,20 @@
 
 	/* teardown kstat, return success */
 	if (! (ui->ui_lock & MD_UL_OPEN)) {
-		mutex_exit(&ui->ui_mx);
-		md_kstat_destroy(mnum);
+
+		/*
+		 * We have a race condition inherited from specfs between
+		 * open() and close() calls. This results in the kstat
+		 * for a pending I/O being torn down, and then a panic.
+		 * To avoid this, only tear the kstat down if there are
+		 * no other readers on this device.
+		 */
+		if (ui->ui_readercnt > 1) {
+			mutex_exit(&ui->ui_mx);
+		} else {
+			mutex_exit(&ui->ui_mx);
+			md_kstat_destroy(mnum);
+		}
 		return (0);
 	}