This file contains functions for constructing and destructing
homa structs.

Signed-off-by: John Ousterhout <ouster@cs.stanford.edu>

---
Changes for v10:
* Remove log messages after alloc errors

Changes for v9:
* Add support for homa_net objects
* Use new homa_clock abstraction layer
* Various name improvements (e.g. use "alloc" instead of "new" for functions
  that allocate memory)

Changes for v8:
* Accommodate homa_pacer refactoring

Changes for v7:
* Make Homa a pernet subsystem
* Add support for tx memory accounting
* Remove "lock_slow" functions, which don't add functionality in this
  patch series
* Use u64 and __u64 properly
---
 net/homa/homa_impl.h  |   6 +++
 net/homa/homa_utils.c | 121 ++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 127 insertions(+)
 create mode 100644 net/homa/homa_utils.c

diff --git a/net/homa/homa_impl.h b/net/homa/homa_impl.h
index a03ee6ca3403..72d646f70381 100644
--- a/net/homa/homa_impl.h
+++ b/net/homa/homa_impl.h
@@ -379,12 +379,18 @@ static inline bool homa_make_header_avl(struct sk_buff *skb)
 
 extern unsigned int homa_net_id;
 
+void     homa_destroy(struct homa *homa);
 int      homa_fill_data_interleaved(struct homa_rpc *rpc,
 				    struct sk_buff *skb, struct iov_iter *iter);
+int      homa_init(struct homa *homa);
 int      homa_message_out_fill(struct homa_rpc *rpc,
 			       struct iov_iter *iter, int xmit);
 void     homa_message_out_init(struct homa_rpc *rpc, int length);
+void     homa_net_destroy(struct homa_net *hnet);
+int      homa_net_init(struct homa_net *hnet, struct net *net,
+		       struct homa *homa);
 void     homa_rpc_handoff(struct homa_rpc *rpc);
+void     homa_spin(int ns);
 struct sk_buff *homa_tx_data_pkt_alloc(struct homa_rpc *rpc,
 				       struct iov_iter *iter, int offset,
 				       int length, int max_seg_data);
diff --git a/net/homa/homa_utils.c b/net/homa/homa_utils.c
new file mode 100644
index 000000000000..75cedb55cad0
--- /dev/null
+++ b/net/homa/homa_utils.c
@@ -0,0 +1,121 @@
+// SPDX-License-Identifier: BSD-2-Clause
+
+/* This file contains miscellaneous utility functions for Homa, such
+ * as initializing and destroying homa structs.
+ */
+
+#include "homa_impl.h"
+#include "homa_pacer.h"
+#include "homa_peer.h"
+#include "homa_rpc.h"
+#include "homa_stub.h"
+
+/**
+ * homa_init() - Constructor for homa objects.
+ * @homa:   Object to initialize.
+ *
+ * Return:  0 on success, or a negative errno if there was an error. Even
+ *          if an error occurs, it is safe (and necessary) to call
+ *          homa_destroy at some point.
+ */
+int homa_init(struct homa *homa)
+{
+	int err;
+
+	memset(homa, 0, sizeof(*homa));
+
+	atomic64_set(&homa->next_outgoing_id, 2);
+	homa->pacer = homa_pacer_alloc(homa);
+	if (IS_ERR(homa->pacer)) {
+		err = PTR_ERR(homa->pacer);
+		homa->pacer = NULL;
+		return err;
+	}
+	homa->peertab = homa_peer_alloc_peertab();
+	if (IS_ERR(homa->peertab)) {
+		err = PTR_ERR(homa->peertab);
+		homa->peertab = NULL;
+		return err;
+	}
+	homa->socktab = kmalloc(sizeof(*homa->socktab), GFP_KERNEL);
+	if (!homa->socktab)
+		return -ENOMEM;
+	homa_socktab_init(homa->socktab);
+
+	/* Wild guesses to initialize configuration values... */
+	homa->resend_ticks = 5;
+	homa->resend_interval = 5;
+	homa->timeout_ticks = 100;
+	homa->timeout_resends = 5;
+	homa->request_ack_ticks = 2;
+	homa->reap_limit = 10;
+	homa->dead_buffs_limit = 5000;
+	homa->max_gso_size = 10000;
+	homa->wmem_max = 100000000;
+	homa->bpage_lease_usecs = 10000;
+	return 0;
+}
+
+/**
+ * homa_destroy() -  Destructor for homa objects.
+ * @homa:      Object to destroy. It is safe if this object has already
+ *             been previously destroyed.
+ */
+void homa_destroy(struct homa *homa)
+{
+	/* The order of the following cleanups matters! */
+	if (homa->socktab) {
+		homa_socktab_destroy(homa->socktab, NULL);
+		kfree(homa->socktab);
+		homa->socktab = NULL;
+	}
+	if (homa->pacer) {
+		homa_pacer_free(homa->pacer);
+		homa->pacer = NULL;
+	}
+	if (homa->peertab) {
+		homa_peer_free_peertab(homa->peertab);
+		homa->peertab = NULL;
+	}
+}
+
+/**
+ * homa_net_init() - Initialize a new struct homa_net as a per-net subsystem.
+ * @hnet:    Struct to initialzie.
+ * @net:     The network namespace the struct will be associated with.
+ * @homa:    The main Homa data structure to use for the net.
+ * Return:  0 on success, otherwise a negative errno.
+ */
+int homa_net_init(struct homa_net *hnet, struct net *net, struct homa *homa)
+{
+	memset(hnet, 0, sizeof(*hnet));
+	hnet->net = net;
+	hnet->homa = homa;
+	hnet->prev_default_port = HOMA_MIN_DEFAULT_PORT - 1;
+	return 0;
+}
+
+/**
+ * homa_net_destroy() - Release any resources associated with a homa_net.
+ * @hnet:    Object to destroy; must not be used again after this function
+ *           returns.
+ */
+void homa_net_destroy(struct homa_net *hnet)
+{
+	homa_socktab_destroy(hnet->homa->socktab, hnet);
+	homa_peer_free_net(hnet);
+}
+
+/**
+ * homa_spin() - Delay (without sleeping) for a given time interval.
+ * @ns:   How long to delay (in nanoseconds)
+ */
+void homa_spin(int ns)
+{
+	u64 end;
+
+	end = homa_clock() + homa_ns_to_cycles(ns);
+	while (homa_clock() < end)
+		/* Empty loop body.*/
+		;
+}
-- 
2.43.0