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Ben Pfaff authored
I know of two reasons to mark a structure as "packed". The first is because the structure must match some defined interface and therefore compiler-inserted padding between or after members would cause its layout to diverge from that interface. This is not a problem in a structure that follows the general alignment rules that are seen in ABIs for all the architectures that OVS cares about: basically, that a struct member needs to be aligned on a boundary that is a multiple of the member's size. The second reason is because instances of the struct tend to be at misaligned addresses. struct eth_header and struct vlan_eth_header are normally aligned on 16-bit boundaries (at least), and they contain only 16-bit members, so there's no need to pack them. This commit removes the packed annotation. This commit also removes the packed annotation from struct llc_header. Since that struct only contains 8-bit members, I don't know of any benefit to packing it, period. This commit also removes a few more packed annotations that are much less important. When these packed annotations were removed, it caused a few warnings related to casts from 'uint8_t *' to more strictly aligned pointer types, related to struct ovs_action_push_tnl. That's because that struct had a trailing member used to store packet headers, that was declared as a uint8_t[]. Before, when this was cast to 'struct eth_header *', there was no change in alignment since eth_header was packed; now that eth_header is not packed, the compiler considers it suspicious. This commit avoids that problem by changing the member from uint8_t[] to uint32_t[], which assures the compiler that it is properly aligned. Signed-off-by: Ben Pfaff <blp@ovn.org> Acked-by: Joe Stringer <joe@ovn.org>
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