greybus: operation: fix potential message corruption

Make sure to allocate the message transfer-buffer separately from the
containing message structure to avoid data corruption on systems without
DMA-coherent caches.

The message structure contains state that is updated while the buffer
may be used for DMA, something which could lead to data corruption due
to cache-line sharing on some architectures.

Use the (renamed) message cache for the message structure itself and
allocate the buffer separately.

If the additional allocation is a concern, the message structures
could eventually be allocated as part of the operation structure.

Signed-off-by: Johan Hovold <johan@hovoldconsulting.com>
Reviewed-by: Alex Elder <elder@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>

1 files changed, 1 insertions, 1 deletions

diff --git a/drivers/staging/greybus/operation.h b/drivers/staging/greybus/operation.h
index cbd347c6b427..647e0bfc54ee 100644
--- a/drivers/staging/greybus/operation.h
+++ b/drivers/staging/greybus/operation.h
@@ -82,7 +82,7 @@ struct gb_message {
 	void				*payload;
 	size_t				payload_size;
 
-	u8				buffer[];
+	void				*buffer;
 };
 
 /*