misc: fastrpc: copy to user only for non-DMA-BUF heap buffers

fastrpc_put_args is copying all the output buffers to user. For large
number of output context buffers, this might cause performance
degradation. Copying is not needed for DMA-BUF heap buffers.

Signed-off-by: Jeya R <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Greg Kroah-Hartman <[e-mail]>

drivers/misc/fastrpc.c

···
 	inbufs = REMOTE_SCALARS_INBUFS(ctx->sc);
 
 	for (i = inbufs; i < ctx->nbufs; ++i) {
-		void *src = (void *)(uintptr_t)rpra[i].pv;
-		void *dst = (void *)(uintptr_t)ctx->args[i].ptr;
-		u64 len = rpra[i].len;
+		if (!ctx->maps[i]) {
+			void *src = (void *)(uintptr_t)rpra[i].pv;
+			void *dst = (void *)(uintptr_t)ctx->args[i].ptr;
+			u64 len = rpra[i].len;
 
-		if (!kernel) {
-			if (copy_to_user((void __user *)dst, src, len))
-				return -EFAULT;
-		} else {
-			memcpy(dst, src, len);
+			if (!kernel) {
+				if (copy_to_user((void __user *)dst, src, len))
+					return -EFAULT;
+			} else {
+				memcpy(dst, src, len);
+			}
 		}
 	}