K 10
svn:author
V 3
ian
K 8
svn:date
V 27
2021-10-06T16:10:32.263953Z
K 7
svn:log
V 851
Fix busdma resource leak on usb device detach.

When a usb device is detached, usb_pc_dmamap_destroy() called
bus_dmamap_destroy() while the map was still loaded. That's harmless on x86
architectures, but on all other platforms it causes bus_dmamap_destroy() to
return EBUSY and leak away any memory resources (including bounce buffers)
associated with the mapping, as well as any allocated map structure itself.

This change introduces a new is_loaded flag to the usb_page_cache struct to
track whether a map is loaded or not. If the map is loaded,
bus_dmamap_unload() is called before bus_dmamap_destroy() to avoid leaking
away resources.

Differential Revision:	https://reviews.freebsd.org/D32208

(cherry picked from commit dc91a9715f8fda4b3633388830a28a99f73cbe59)

Git Hash:   6fea4b82e7b86ac680d5615f8361863353737325
Git Author: ian@FreeBSD.org
END