MINOR: server: remove prev_deleted server list

This patch is a direct follow-up to the previous one. Thanks to watcher
type, it is not safe to assume that servers manipulated via stats dump
were not targetted by a "delete server" CLI command. As such,
prev_deleted list server member is now unneeded. This patch thus removes
any reference to it.

include/haproxy/server-t.h

@@ -303,7 +303,6 @@ struct server {
 	unsigned int pp_opts;                   /* proxy protocol options (SRV_PP_*) */
 	struct mt_list global_list;             /* attach point in the global servers_list */
 	struct server *next;
-	struct mt_list prev_deleted;            /* deleted servers with 'next' ptr pointing to us */
 	int cklen;				/* the len of the cookie, to speed up checks */
 	int rdr_len;				/* the length of the redirection prefix */
 	char *cookie;				/* the id set in the cookie */

src/server.c

@@ -2966,7 +2966,6 @@ struct server *new_server(struct proxy *proxy)
 	LIST_INIT(&srv->srv_rec_item);
 	LIST_INIT(&srv->ip_rec_item);
 	LIST_INIT(&srv->pp_tlvs);
-	MT_LIST_INIT(&srv->prev_deleted);
 	event_hdl_sub_list_init(&srv->e_subs);
 	srv->rid = 0; /* rid defaults to 0 */
 
@@ -3074,13 +3073,6 @@ struct server *srv_drop(struct server *srv)
 
 	guid_remove(&srv->guid);
 
-	/* make sure we are removed from our 'next->prev_deleted' list
-	 * This doesn't require full thread isolation as we're using mt lists
-	 * However this could easily be turned into regular list if required
-	 * (with the proper use of thread isolation)
-	 */
-	MT_LIST_DELETE(&srv->prev_deleted);
-
 	task_destroy(srv->warmup);
 	task_destroy(srv->srvrq_check);
 
@@ -6073,7 +6065,6 @@ static int cli_parse_delete_server(char **args, char *payload, struct appctx *ap
 {
 	struct proxy *be;
 	struct server *srv;
-	struct server *prev_del;
 	struct ist be_name, sv_name;
 	struct mt_list back;
 	struct sess_priv_conns *sess_conns = NULL;
@@ -6191,26 +6182,6 @@ static int cli_parse_delete_server(char **args, char *payload, struct appctx *ap
 	 */
 	_srv_detach(srv);
 
-	/* Some deleted servers could still point to us using their 'next',
-	 * migrate them as needed
-	 */
-	MT_LIST_FOR_EACH_ENTRY_LOCKED(prev_del, &srv->prev_deleted, prev_deleted, back) {
-		/* update its 'next' ptr */
-		prev_del->next = srv->next;
-		if (srv->next) {
-			/* now it is our 'next' responsibility */
-			MT_LIST_APPEND(&srv->next->prev_deleted, &prev_del->prev_deleted);
-		}
-		else
-			mt_list_unlock_self(&prev_del->prev_deleted);
-		/* unlink from our list */
-		prev_del = NULL;
-	}
-
-	/* we ourselves need to inform our 'next' that we will still point it */
-	if (srv->next)
-		MT_LIST_APPEND(&srv->next->prev_deleted, &srv->prev_deleted);
-
 	/* remove srv from addr_node tree */
 	eb32_delete(&srv->conf.id);
 	ebpt_delete(&srv->conf.name);