mir/ovs
2
0
Fork 0
mirror of https://github.com/openvswitch/ovs synced 2025-09-01 23:05:29 +00:00
Code Issues Releases Wiki Activity

packets: Remove unnecessary "packed" annotations.

Browse Source 
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>
This commit is contained in:
Ben Pfaff
2017-05-30 08:22:03 -07:00
parent c1efab9b13
commit 1620b7ea68
5 changed files with 10 additions and 15 deletions
Download Patch File Download Diff File Expand all files Collapse all files

2
datapath/linux/compat/include/linux/openvswitch.h
View File

@@ -715,7 +715,7 @@ struct ovs_action_push_tnl {
uint32_t out_port;
uint32_t header_len;
uint32_t tnl_type; /* For logging. */
uint8_t header[TNL_PUSH_HEADER_SIZE];
uint32_t header[TNL_PUSH_HEADER_SIZE / 4];
};
#endif

2
lib/odp-util.c
View File

@@ -1136,7 +1136,7 @@ ovs_parse_tnl_push(const char *s, struct ovs_action_push_tnl *data)
return -EINVAL;
}
eth = (struct eth_header *) data->header;
l3 = (data->header + sizeof *eth);
l3 = (struct ip_header *) (eth + 1);
ip = (struct ip_header *) l3;
ip6 = (struct ovs_16aligned_ip6_hdr *) l3;
if (!ovs_scan_len(s, &n, "header(size=%"SCNi32",type=%"SCNi32","

9
lib/packets.h
View File

@@ -395,12 +395,11 @@ static inline bool eth_type_vlan(ovs_be16 eth_type)
#define ETH_TOTAL_MIN (ETH_HEADER_LEN + ETH_PAYLOAD_MIN)
#define ETH_TOTAL_MAX (ETH_HEADER_LEN + ETH_PAYLOAD_MAX)
#define ETH_VLAN_TOTAL_MAX (ETH_HEADER_LEN + VLAN_HEADER_LEN + ETH_PAYLOAD_MAX)
OVS_PACKED(
struct eth_header {
struct eth_addr eth_dst;
struct eth_addr eth_src;
ovs_be16 eth_type;
});
};
BUILD_ASSERT_DECL(ETH_HEADER_LEN == sizeof(struct eth_header));
void push_eth(struct dp_packet *packet, const struct eth_addr *dst,
@@ -412,12 +411,11 @@ void pop_eth(struct dp_packet *packet);
#define LLC_CNTL_SNAP 3
#define LLC_HEADER_LEN 3
OVS_PACKED(
struct llc_header {
uint8_t llc_dsap;
uint8_t llc_ssap;
uint8_t llc_cntl;
});
};
BUILD_ASSERT_DECL(LLC_HEADER_LEN == sizeof(struct llc_header));
/* LLC field values used for STP frames. */
@@ -484,14 +482,13 @@ struct vlan_header {
BUILD_ASSERT_DECL(VLAN_HEADER_LEN == sizeof(struct vlan_header));
#define VLAN_ETH_HEADER_LEN (ETH_HEADER_LEN + VLAN_HEADER_LEN)
OVS_PACKED(
struct vlan_eth_header {
struct eth_addr veth_dst;
struct eth_addr veth_src;
ovs_be16 veth_type; /* Always htons(ETH_TYPE_VLAN). */
ovs_be16 veth_tci; /* Lowest 12 bits are VLAN ID. */
ovs_be16 veth_next_type;
});
};
BUILD_ASSERT_DECL(VLAN_ETH_HEADER_LEN == sizeof(struct vlan_eth_header));
/* MPLS related definitions */

8
lib/stp.c
View File

@@ -1,5 +1,5 @@
/*
* Copyright (c) 2008, 2009, 2010, 2011, 2012, 2013, 2014, 2016 Nicira, Inc.
* Copyright (c) 2008-2014, 2016-2017 Nicira, Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
@@ -45,12 +45,11 @@ static struct vlog_rate_limit stp_rl = VLOG_RATE_LIMIT_INIT(60, 60);
#define STP_TYPE_CONFIG 0x00
#define STP_TYPE_TCN 0x80
OVS_PACKED(
struct stp_bpdu_header {
ovs_be16 protocol_id; /* STP_PROTOCOL_ID. */
uint8_t protocol_version; /* STP_PROTOCOL_VERSION. */
uint8_t bpdu_type; /* One of STP_TYPE_*. */
});
};
BUILD_ASSERT_DECL(sizeof(struct stp_bpdu_header) == 4);
enum stp_config_bpdu_flags {
@@ -73,10 +72,9 @@ struct stp_config_bpdu {
});
BUILD_ASSERT_DECL(sizeof(struct stp_config_bpdu) == 35);
OVS_PACKED(
struct stp_tcn_bpdu {
struct stp_bpdu_header header; /* Type STP_TYPE_TCN. */
});
};
BUILD_ASSERT_DECL(sizeof(struct stp_tcn_bpdu) == 4);
struct stp_timer {

4
ofproto/bundles.h
View File

@@ -1,7 +1,7 @@
/*
* Copyright (c) 2013, 2014 Alexandru Copot <alex.mihai.c@gmail.com>, with support from IXIA.
* Copyright (c) 2013, 2014 Daniel Baluta <dbaluta@ixiacom.com>
* Copyright (c) 2014, 2015, 2016 Nicira, Inc.
* Copyright (c) 2014, 2015, 2016, 2017 Nicira, Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
@@ -49,7 +49,7 @@ struct ofp_bundle_entry {
};
};
enum OVS_PACKED_ENUM bundle_state {
enum bundle_state {
BS_OPEN,
BS_CLOSED
};