MFp4:

If we panicked with SIM lock held, do not try to flush caches.
Extra lock recursing will not make debugging easier.

sys/cam/ata/ata_da.c

@@ -1040,6 +1040,9 @@ adashutdown(void * arg, int howto)
 	TAILQ_FOREACH(periph, &adadriver.units, unit_links) {
 		union ccb ccb;
 
+		/* If we paniced with lock held - not recurse here. */
+		if (cam_periph_owned(periph))
+			continue;
 		cam_periph_lock(periph);
 		softc = (struct ada_softc *)periph->softc;
 		/*

sys/cam/cam_periph.h

@@ -190,5 +190,11 @@ cam_periph_unlock(struct cam_periph *periph)
 	mtx_unlock(periph->sim->mtx);
 }
 
+static __inline int
+cam_periph_owned(struct cam_periph *periph)
+{
+	return (mtx_owned(periph->sim->mtx));
+}
+
 #endif /* _KERNEL */
 #endif /* _CAM_CAM_PERIPH_H */