svn commit: r339478 - head/sys/kern

[Conrad Meyer]

Author: cem
Date: Sat Oct 20 19:42:38 2018
New Revision: 339478
URL: https://svnweb.freebsd.org/changeset/base/339478

Log:
  dev_refthread: Do not initialize *ref when reference was not acquired
  
  Like the companion API devvn_refthread, leave *ref uninitialized when a
  reference was not acquired.  Initializing to 1 provides a vaguely
  correct-looking but bogus value for broken callers to (mistakenly) pass to
  dev_relthread() when refthread fails.
  
  Make it even more clear to consumers that dev_relthread is only valid when
  dev_refthread succeeds.
  
  Reviewed by:	kib, markj
  Sponsored by:	Dell EMC Isilon
  Differential Revision:	https://reviews.freebsd.org/D16885

Modified:
  head/sys/kern/kern_conf.c

Modified: head/sys/kern/kern_conf.c
==============================================================================
--- head/sys/kern/kern_conf.c	Sat Oct 20 19:18:30 2018	(r339477)
+++ head/sys/kern/kern_conf.c	Sat Oct 20 19:42:38 2018	(r339478)
@@ -202,7 +202,8 @@ dev_refthread(struct cdev *dev, int *ref)
 			csw = NULL;
 	}
 	dev_unlock();
-	*ref = 1;
+	if (csw != NULL)
+		*ref = 1;
 	return (csw);
 }