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| author | Thomas Gleixner <tglx@linutronix.de> | 2016-01-12 11:01:12 +0100 |
|---|---|---|
| committer | Thomas Gleixner <tglx@linutronix.de> | 2016-01-12 11:01:12 +0100 |
| commit | 1f16f116b01c110db20ab808562c8b8bc3ee3d6e (patch) | |
| tree | 44db563f64cf5f8d62af8f99a61e2b248c44ea3a /include/xen/interface/io/ring.h | |
| parent | 03724ac3d48f8f0e3caf1d30fa134f8fd96c94e2 (diff) | |
| parent | f9eccf24615672896dc13251410c3f2f33a14f95 (diff) | |
| download | linux-1f16f116b01c110db20ab808562c8b8bc3ee3d6e.tar.gz linux-1f16f116b01c110db20ab808562c8b8bc3ee3d6e.tar.xz | |
Merge branches 'clockevents/4.4-fixes' and 'clockevents/4.5-fixes' of http://git.linaro.org/people/daniel.lezcano/linux into timers/urgent
Pull in fixes from Daniel Lezcano:
- Fix the vt8500 timer leading to a system lock up when dealing with too
small delta (Roman Volkov)
- Select the CLKSRC_MMIO when the fsl_ftm_timer is enabled with COMPILE_TEST
(Daniel Lezcano)
- Prevent to compile timers using the 'iomem' API when the architecture has
not HAS_IOMEM set (Richard Weinberger)
Diffstat (limited to 'include/xen/interface/io/ring.h')
| -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)) |