...to keep migration sane. Right now, the biggest struct in union flow
is struct tcp_splice_conn with 120 bytes on x86_64, which should also
have the biggest storage and alignment requirements of any
architecture we might run on.
Signed-off-by: Stefano Brivio <sbrivio(a)redhat.com>
---
flow.h | 18 ++++++++++++------
flow_table.h | 13 ++++++++++---
2 files changed, 22 insertions(+), 9 deletions(-)
diff --git a/flow.h b/flow.h
index 24ba3ef..8eb5964 100644
--- a/flow.h
+++ b/flow.h
@@ -202,15 +202,21 @@ struct flow_common {
/**
* struct flow_sidx - ID for one side of a specific flow
- * @sidei: Index of side referenced (0 or 1)
- * @flowi: Index of flow referenced
+ * @sidei: Index of side referenced (0 or 1)
+ * @flowi: Index of flow referenced
+ * @flow_sidx_storage: Pad to 32 bits
*/
typedef struct flow_sidx {
- unsigned sidei :1;
- unsigned flowi :FLOW_INDEX_BITS;
+ union {
+ struct {
+ unsigned sidei :1;
+ unsigned flowi :FLOW_INDEX_BITS;
+ };
+ uint32_t flow_sidx_storage;
+ };
} flow_sidx_t;
-static_assert(sizeof(flow_sidx_t) <= sizeof(uint32_t),
- "flow_sidx_t must fit within 32 bits");
+static_assert(sizeof(flow_sidx_t) == sizeof(uint32_t),
+ "flow_sidx_t must be 32-bit wide");
#define FLOW_SIDX_NONE ((flow_sidx_t){ .flowi = FLOW_MAX })
diff --git a/flow_table.h b/flow_table.h
index f15db53..007f4dd 100644
--- a/flow_table.h
+++ b/flow_table.h
@@ -26,9 +26,13 @@ struct flow_free_cluster {
/**
* union flow - Descriptor for a logical packet flow (e.g. connection)
- * @f: Fields common between all variants
- * @tcp: Fields for non-spliced TCP connections
- * @tcp_splice: Fields for spliced TCP connections
+ * @f: Fields common between all variants
+ * @free: Entry in a cluster of free entries
+ * @tcp: Fields for non-spliced TCP connections
+ * @tcp_splice: Fields for spliced TCP connections
+ * @ping: Tracking for ping flows
+ * @udp: Tracking for UDP flows
+ * @flow_storage: Pad flow entries to 128 bytes to ease state migration
*/
union flow {
struct flow_common f;
@@ -37,8 +41,11 @@ union flow {
struct tcp_splice_conn tcp_splice;
struct icmp_ping_flow ping;
struct udp_flow udp;
+ char flow_storage[128];
};
+static_assert(sizeof(union flow) == 128, "union flow should be 128-byte
wide");
+
/* Global Flow Table */
extern unsigned flow_first_free;
extern union flow flowtab[];
--
2.43.0