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[net-next,V1,06/11] net/mlx4_core: Fix struct mlx4_vhcr_cmd to make implicit padding explicit

Message ID 1422367089-13419-7-git-send-email-amirv@mellanox.com
State Accepted, archived
Delegated to: David Miller
Headers show

Commit Message

Amir Vadai Jan. 27, 2015, 1:58 p.m. UTC 
From: Jack Morgenstein <jackm@dev.mellanox.co.il>

Struct mlx4_vhcr was implicitly padded by the gcc compiler on 64-bit
architectures.

This commit makes that padding explicit, to prevent issues with
changing compilers and with incompatibilities between 32-bit architecture
implicit padding and 64-bit architecture implicit padding.

This structure is used in virtualization for communication between
the Host and its Guests. The explicit padding allows 64-bit Hosts
(old and new) to continue to interoperate with 64-bit Guests (old and new).

However, without this fix, 64-bit Hosts could not interoperate with 32-bit
Guests (since these did not insert the padding dword). With this fix,
32-bit Guests will be able to interoperate with 64-bit Hosts (since
the structure offsets will be identical on both).


Reported-by: Alexander Schmidt <alexs@linux.vnet.ibm.com>
Signed-off-by: Jack Morgenstein <jackm@dev.mellanox.co.il>
Signed-off-by: Amir Vadai <amirv@mellanox.com>
---
 drivers/net/ethernet/mellanox/mlx4/mlx4.h | 1 +
 1 file changed, 1 insertion(+)
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Patch

diff --git a/drivers/net/ethernet/mellanox/mlx4/mlx4.h b/drivers/net/ethernet/mellanox/mlx4/mlx4.h
index 096a81c..148dc09 100644
--- a/drivers/net/ethernet/mellanox/mlx4/mlx4.h
+++ b/drivers/net/ethernet/mellanox/mlx4/mlx4.h
@@ -196,6 +196,7 @@  struct mlx4_vhcr {
 struct mlx4_vhcr_cmd {
 	__be64 in_param;
 	__be32 in_modifier;
+	u32 reserved1;
 	__be64 out_param;
 	__be16 token;
 	u16 reserved;