netdev - [PATCH net-next] xen-netback: update ubuf_info initialization to anonymous union

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Message-Id: <20170825171043.84011-1-willemdebruijn.kernel@gmail.com>
Date:   Fri, 25 Aug 2017 13:10:43 -0400
From:   Willem de Bruijn <willemdebruijn.kernel@...il.com>
To:     netdev@...r.kernel.org
Cc:     davem@...emloft.net, wei.liu2@...rix.com, paul.durrant@...rix.com,
        kbuild-all@...org, Willem de Bruijn <willemb@...gle.com>
Subject: [PATCH net-next] xen-netback: update ubuf_info initialization to anonymous union

From: Willem de Bruijn <willemb@...gle.com>

The xen driver initializes struct ubuf_info fields using designated
initializers. I recently moved these fields inside a nested anonymous
struct inside an anonymous union. I had missed this use case.

This breaks compilation of xen-netback with older compilers.
>From kbuild bot with gcc-4.4.7:

   drivers/net//xen-netback/interface.c: In function
   'xenvif_init_queue':
   >> drivers/net//xen-netback/interface.c:554: error: unknown field 'ctx' specified in initializer
   >> drivers/net//xen-netback/interface.c:554: warning: missing braces around initializer
      drivers/net//xen-netback/interface.c:554: warning: (near initialization for '(anonymous).<anonymous>')
   >> drivers/net//xen-netback/interface.c:554: warning: initialization makes integer from pointer without a cast
   >> drivers/net//xen-netback/interface.c:555: error: unknown field 'desc' specified in initializer

Add double braces around the designated initializers to match their
nested position in the struct. After this, compilation succeeds again.

Fixes: 4ab6c99d99bb ("sock: MSG_ZEROCOPY notification coalescing")
Reported-by: kbuild bot <lpk@...el.com>
Signed-off-by: Willem de Bruijn <willemb@...gle.com>
---
 drivers/net/xen-netback/interface.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/net/xen-netback/interface.c b/drivers/net/xen-netback/interface.c
index e322a862ddfe..ee8ed9da00ad 100644
--- a/drivers/net/xen-netback/interface.c
+++ b/drivers/net/xen-netback/interface.c
@@ -551,8 +551,8 @@ int xenvif_init_queue(struct xenvif_queue *queue)
 	for (i = 0; i < MAX_PENDING_REQS; i++) {
 		queue->pending_tx_info[i].callback_struct = (struct ubuf_info)
 			{ .callback = xenvif_zerocopy_callback,
-			  .ctx = NULL,
-			  .desc = i };
+			  { { .ctx = NULL,
+			      .desc = i } } };
 		queue->grant_tx_handle[i] = NETBACK_INVALID_HANDLE;
 	}
 
-- 
2.14.1.342.g6490525c54-goog