witness: report a thread that can't sleep in WITNESS_WARN

Although this is not related to locking, but seems to be the right
place to catch violators, given that WITNESS_WARN is already used
widely in the kernel.

Reviewed by:		kib, markj
Differential Revision:	https://reviews.freebsd.org/D55316

1 files changed, 9 insertions, 0 deletions

diff --git a/sys/kern/subr_witness.c b/sys/kern/subr_witness.c
index 7437a7e238f0..85dc0c321797 100644
--- a/sys/kern/subr_witness.c
+++ b/sys/kern/subr_witness.c
@@ -2136,6 +2136,15 @@ witness_warn(int flags, struct lock_object *lock, const char *fmt, ...)
 		n += witness_list_locks(&lock_list, printf);
 	} else
 		sched_unpin();
+
+	if (td->td_no_sleeping != 0 && (flags & WARN_SLEEPOK) != 0) {
+		va_start(ap, fmt);
+		vprintf(fmt, ap);
+		va_end(ap);
+		printf(" with %d sleep inhibitors\n", td->td_no_sleeping);
+		n += td->td_no_sleeping;
+	}
+
 	if (flags & WARN_PANIC && n)
 		kassert_panic("%s", __func__);
 	else