Re: usb: does USBMALLOC_ZERO work correctly?

[Jared McNeill]

Good catch! I've committed a slightly modified version of your patch.

Take care,
Jared


On Thu, 27 May 2021, sc.dy...@gmail.com wrote:

hi,

sometimes memories allocated by usb_allocmem with USBMALLOC_ZERO
are not cleared.
usb_block_allocmem, called from usb_allocmem, returns with valid dmap
if it has found a block in usb_blk_freelist. In that path memset is not done.


--- src/sys/dev/usb/usb_mem.c.orig      2021-01-05 22:12:39.913414469 +0000
+++ src/sys/dev/usb/usb_mem.c   2021-05-27 01:36:53.189148366 +0000
@@ -135,6 +135,11 @@ usb_block_allocmem(bus_dma_tag_t tag, si
                        usb_blk_nfree--;
                        *dmap = b;
                        DPRINTFN(6, "free list size=%ju", b->size, 0, 0, 0);
+                       if ((flags & USBMALLOC_ZERO) != 0) {
+                               memset(b->kaddr, 0, b->size);
+                               bus_dmamap_sync(b->tag, b->map, 0, b->size,
+                                   BUS_DMASYNC_PREWRITE);
+                       }
                        return 0;
                }
        }