diff options
| author | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2015-12-21 11:11:12 -0800 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2015-12-21 11:11:12 -0800 |
| commit | bfccd95e7aba73d0d3154912b17b855cb9938c50 (patch) | |
| tree | 3250b7806b873170a3ff7dba0aa1664e57c5bde9 /include/xen/interface | |
| parent | 252ca494ac75f0dc47469f130d6dc67ed14081f4 (diff) | |
| parent | 4ef7675344d687a0ef5b0d7c0cee12da005870c0 (diff) | |
Merge 4.4-rc6 into usb-next
We want the USB and PHY fixes in here as well to make things easier for
testing and development.
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'include/xen/interface')
| -rw-r--r-- | include/xen/interface/io/ring.h | 14 |
1 files changed, 14 insertions, 0 deletions
diff --git a/include/xen/interface/io/ring.h b/include/xen/interface/io/ring.h index 7d28aff605c7..7dc685b4057d 100644 --- a/include/xen/interface/io/ring.h +++ b/include/xen/interface/io/ring.h @@ -181,6 +181,20 @@ struct __name##_back_ring { \ #define RING_GET_REQUEST(_r, _idx) \ (&((_r)->sring->ring[((_idx) & (RING_SIZE(_r) - 1))].req)) +/* + * Get a local copy of a request. + * + * Use this in preference to RING_GET_REQUEST() so all processing is + * done on a local copy that cannot be modified by the other end. + * + * Note that https://gcc.gnu.org/bugzilla/show_bug.cgi?id=58145 may cause this + * to be ineffective where _req is a struct which consists of only bitfields. + */ +#define RING_COPY_REQUEST(_r, _idx, _req) do { \ + /* Use volatile to force the copy into _req. */ \ + *(_req) = *(volatile typeof(_req))RING_GET_REQUEST(_r, _idx); \ +} while (0) + #define RING_GET_RESPONSE(_r, _idx) \ (&((_r)->sring->ring[((_idx) & (RING_SIZE(_r) - 1))].rsp)) |