witness: sleepable rm locks are not sleepable in read mode

There are two classes of rm lock, one "sleepable" and one not.  But even
a "sleepable" rm lock is only sleepable in write mode, and is
non-sleepable when taken in read mode.

Warn about sleepable rm locks in read mode as non-sleepable locks.  Do
this by defining a new lock operation flag, LOP_NOSLEEP, to indicate
that a lock is non-sleepable despite what the LO_SLEEPABLE flag would
indicate, and defining a new witness lock instance flag, LI_SLEEPABLE,
to track the product of LO_SLEEPABLE and LOP_NOSLEEP on the lock
instance.

Reviewed by:	markj
Sponsored by:	Dell EMC Isilon
Differential Revision:	https://reviews.freebsd.org/D22527

1 files changed, 3 insertions, 3 deletions

diff --git a/sys/kern/kern_rmlock.c b/sys/kern/kern_rmlock.c
index 5cb18fbfa582..96e11276e9b2 100644
--- a/sys/kern/kern_rmlock.c
+++ b/sys/kern/kern_rmlock.c
@@ -652,8 +652,8 @@ _rm_rlock_debug(struct rmlock *rm, struct rm_priotracker *tracker,
 		KASSERT(!rm_wowned(rm),
 		    ("rm_rlock: wlock already held for %s @ %s:%d",
 		    rm->lock_object.lo_name, file, line));
-		WITNESS_CHECKORDER(&rm->lock_object, LOP_NEWORDER, file, line,
-		    NULL);
+		WITNESS_CHECKORDER(&rm->lock_object,
+		    LOP_NEWORDER | LOP_NOSLEEP, file, line, NULL);
 	}
 
 	if (_rm_rlock(rm, tracker, trylock)) {
@@ -663,7 +663,7 @@ _rm_rlock_debug(struct rmlock *rm, struct rm_priotracker *tracker,
 		else
 			LOCK_LOG_LOCK("RMRLOCK", &rm->lock_object, 0, 0, file,
 			    line);
-		WITNESS_LOCK(&rm->lock_object, 0, file, line);
+		WITNESS_LOCK(&rm->lock_object, LOP_NOSLEEP, file, line);
 		TD_LOCKS_INC(curthread);
 		return (1);
 	} else if (trylock)