tcp: Rework timers to use timerfd instead of periodic bitmap scan

With a lot of concurrent connections, the bitmap scan approach is
not really sustainable.

Switch to per-connection timerfd timers, set based on events and on
two new flags, ACK_FROM_TAP_DUE and ACK_TO_TAP_DUE. Timers are added
to the common epoll list, and implement the existing timeouts.

While at it, drop the CONN_ prefix from flag names, otherwise they
get quite long, and fix the logic to decide if a connection has a
local, possibly unreachable endpoint: we shouldn't go through the
rest of tcp_conn_from_tap() if we reset the connection due to a
successful bind(2), and we'll get EACCES if the port number is low.

Suggested by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>

1 files changed, 1 insertions, 1 deletions

diff --git a/tap.c b/tap.c
index a1ccfc1..59a87f9 100644
--- a/tap.c
+++ b/tap.c
@@ -939,7 +939,7 @@ void tap_sock_init(struct ctx *c)
  * @c:		Execution context
  * @fd:		File descriptor where event occurred
  * @events:	epoll events
- * @now:	Current timestamp
+ * @now:	Current timestamp, can be NULL on EPOLLERR
  */
 void tap_handler(struct ctx *c, int fd, uint32_t events, struct timespec *now)
 {