[PATCH net-next v18 10/15] net: homa: create homa_utils.c

John Ousterhout
2026-04-10T20:03:38Z

This file contains functions for constructing and destructing
homa structs.

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

---
Changes for v16:
* Use cpu_relax when spinning

Changes for v11:
* Move link_mbps variable from struct homa_pacer back to struct homa

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 | 110 ++++++++++++++++++++++++++++++++++++++++++
2 files changed, 116 insertions(+)
create mode 100644 net/homa/homa_utils.c

diff --git a/net/homa/homa_impl.h b/net/homa/homa_impl.h
index cf8a0b64cc6a..e997f1f6cb3b 100644
--- a/net/homa/homa_impl.h
+++ b/net/homa/homa_impl.h
@@ -359,13 +359,19 @@ 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);
int homa_rpc_tx_end(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..df3845fb9417
--- /dev/null
+++ b/net/homa/homa_utils.c
@@ -0,0 +1,110 @@
+// SPDX-License-Identifier: BSD-2-Clause or GPL-2.0+
+
+/* This file contains miscellaneous utility functions for Homa, such
+ * as initializing and destroying homa structs.
+ */
+
+#include "homa_impl.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->link_mbps = 25000;
+ 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->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->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)
+ cpu_relax();
+}
--
2.43.0