Drivers: hv: vmbus: Use *_ONCE() to access shared ring buffer indices

The ring buffer read/write indices live in a page shared with the host,
so the compiler must not split, merge or refetch accesses to them. Add
READ_ONCE()/WRITE_ONCE() in hv_set_next_write_location(),
hv_pkt_iter_close(), hv_get_bytes_to_read() and hv_get_bytes_to_write().
The accesses in hv_ringbuffer_get_debuginfo() are left to the next
patch.

Drop hv_get_ring_bufferindices(). It has one caller and is a one-line
expression on the write index. Inlining it moves the access to the call
site, so hv_ringbuffer_write() can reuse its validated snapshot of that
index, old_write, rather than reading the shared memory a second time.

No functional change intended for a well-behaved host.

Reviewed-by: Michael Kelley <mhklinux@outlook.com>
Signed-off-by: Kameron Carr <kameroncarr@linux.microsoft.com>
Signed-off-by: Wei Liu <wei.liu@kernel.org>

0 files changed, 0 insertions, 0 deletions