Currently, the tables for spliced and non-spliced connections are entirely
separate, with different types in different arrays. We want to unify them.
As a first step, create a union type which can represent either a spliced
or non-spliced connection. For them to be distinguishable, the individual
types need to have a common header added, with a bit indicating which type
this structure is.
This comes at the cost of increasing the size of tcp_tap_conn to over one
(64 byte) cacheline. This isn't ideal, but it makes things simpler for now
and we'll re-optimize this later.
Signed-off-by: David Gibson <david(a)gibson.dropbear.id.au>
---
tcp.c | 4 ++++
tcp_conn.h | 30 ++++++++++++++++++++++++++++++
tcp_splice.c | 2 ++
3 files changed, 36 insertions(+)
diff --git a/tcp.c b/tcp.c
index 189041c..05eed85 100644
--- a/tcp.c
+++ b/tcp.c
@@ -288,6 +288,7 @@
#include <sys/uio.h>
#include <unistd.h>
#include <time.h>
+#include <assert.h>
#include <linux/tcp.h> /* For struct tcp_info */
@@ -601,6 +602,7 @@ static inline struct tcp_tap_conn *conn_at_idx(int index)
{
if ((index < 0) || (index >= TCP_MAX_CONNS))
return NULL;
+ assert(!(CONN(index)->c.spliced));
return CONN(index);
}
@@ -2096,6 +2098,7 @@ static void tcp_conn_from_tap(struct ctx *c, int af, const void
*addr,
}
conn = CONN(c->tcp.conn_count++);
+ conn->c.spliced = false;
conn->sock = s;
conn->timer = -1;
conn_event(c, conn, TAP_SYN_RCVD);
@@ -2764,6 +2767,7 @@ static void tcp_conn_from_sock(struct ctx *c, union epoll_ref ref,
return;
conn = CONN(c->tcp.conn_count++);
+ conn->c.spliced = false;
conn->sock = s;
conn->timer = -1;
conn->ws_to_tap = conn->ws_from_tap = 0;
diff --git a/tcp_conn.h b/tcp_conn.h
index db4c2d9..39d104a 100644
--- a/tcp_conn.h
+++ b/tcp_conn.h
@@ -11,8 +11,19 @@
#define TCP_HASH_BUCKET_BITS (TCP_CONN_INDEX_BITS + 1)
+/**
+ * struct tcp_conn_common - Common fields for spliced and non-spliced
+ * @spliced: Is this a spliced connection?
+ */
+struct tcp_conn_common {
+ bool spliced :1;
+};
+
+extern const char *tcp_common_flag_str[];
+
/**
* struct tcp_tap_conn - Descriptor for a TCP connection (not spliced)
+ * @c: Fields common with tcp_splice_conn
* @next_index: Connection index of next item in hash chain, -1 for none
* @tap_mss: MSS advertised by tap/guest, rounded to 2 ^ TCP_MSS_BITS
* @sock: Socket descriptor number
@@ -40,6 +51,9 @@
* @seq_init_from_tap: Initial sequence number from tap
*/
struct tcp_tap_conn {
+ /* Must be first element to match tcp_splice_conn */
+ struct tcp_conn_common c;
+
int next_index :TCP_CONN_INDEX_BITS + 2;
#define TCP_RETRANS_BITS 3
@@ -122,6 +136,7 @@ struct tcp_tap_conn {
/**
* struct tcp_splice_conn - Descriptor for a spliced TCP connection
+ * @c: Fields common with tcp_tap_conn
* @a: File descriptor number of socket for accepted connection
* @pipe_a_b: Pipe ends for splice() from @a to @b
* @b: File descriptor number of peer connected socket
@@ -134,6 +149,9 @@ struct tcp_tap_conn {
* @b_written: Bytes written to @b (not fully written from one @a read)
*/
struct tcp_splice_conn {
+ /* Must be first element to match tcp_tap_conn */
+ struct tcp_conn_common c;
+
int a;
int pipe_a_b[2];
int b;
@@ -165,4 +183,16 @@ struct tcp_splice_conn {
uint32_t b_written;
};
+/**
+ * union tcp_conn - Descriptor for a TCP connection (spliced or non-spliced)
+ * @c: Fields common between all variants
+ * @tap: Fields specific to non-spliced connections
+ * @splice: Fields specific to spliced connections
+*/
+union tcp_conn {
+ struct tcp_conn_common c;
+ struct tcp_tap_conn tap;
+ struct tcp_splice_conn splice;
+};
+
#endif /* TCP_CONN_H */
diff --git a/tcp_splice.c b/tcp_splice.c
index cbfab01..d8be91b 100644
--- a/tcp_splice.c
+++ b/tcp_splice.c
@@ -46,6 +46,7 @@
#include <sys/epoll.h>
#include <sys/types.h>
#include <sys/socket.h>
+#include <assert.h>
#include "util.h"
#include "passt.h"
@@ -554,6 +555,7 @@ void tcp_sock_handler_splice(struct ctx *c, union epoll_ref ref,
}
conn = CONN(c->tcp.splice_conn_count++);
+ conn->c.spliced = true;
conn->a = s;
conn->flags = ref.r.p.tcp.tcp.v6 ? SPLICE_V6 : 0;
--
2.38.1