netdev - [PATCH net-next v7 10/14] net: homa: create homa

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Message-ID: <20250331234548.62070-11-ouster@cs.stanford.edu>
Date: Mon, 31 Mar 2025 16:45:43 -0700
From: John Ousterhout <ouster@...stanford.edu>
To: netdev@...r.kernel.org
Cc: pabeni@...hat.com,
	edumazet@...gle.com,
	horms@...nel.org,
	kuba@...nel.org,
	John Ousterhout <ouster@...stanford.edu>
Subject: [PATCH net-next v7 10/14] net: homa: create homa_utils.c

This file contains functions for constructing and destructing
homa structs.

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

---
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_utils.c | 118 ++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 118 insertions(+)
 create mode 100644 net/homa/homa_utils.c

diff --git a/net/homa/homa_utils.c b/net/homa/homa_utils.c
new file mode 100644
index 000000000000..b9d46eeb8274
--- /dev/null
+++ b/net/homa/homa_utils.c
@@ -0,0 +1,118 @@
+// 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_peer.h"
+#include "homa_rpc.h"
+#include "homa_stub.h"
+
+struct completion homa_pacer_kthread_done;
+
+/**
+ * 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));
+	init_completion(&homa_pacer_kthread_done);
+	atomic64_set(&homa->next_outgoing_id, 2);
+	atomic64_set(&homa->link_idle_time, sched_clock());
+	spin_lock_init(&homa->pacer_mutex);
+	homa->pacer_fifo_fraction = 50;
+	homa->pacer_fifo_count = 1;
+	spin_lock_init(&homa->throttle_lock);
+	INIT_LIST_HEAD_RCU(&homa->throttled_rpcs);
+	homa->throttle_min_bytes = 200;
+	homa->prev_default_port = HOMA_MIN_DEFAULT_PORT - 1;
+	homa->port_map = kmalloc(sizeof(*homa->port_map), GFP_KERNEL);
+	if (!homa->port_map) {
+		pr_err("%s couldn't create port_map: kmalloc failure",
+		       __func__);
+		return -ENOMEM;
+	}
+	homa_socktab_init(homa->port_map);
+	homa->peers = kmalloc(sizeof(*homa->peers), GFP_KERNEL);
+	if (!homa->peers) {
+		pr_err("%s couldn't create peers: kmalloc failure", __func__);
+		return -ENOMEM;
+	}
+	err = homa_peertab_init(homa->peers);
+	if (err) {
+		pr_err("%s couldn't initialize peer table (errno %d)\n",
+		       __func__, -err);
+		return err;
+	}
+
+	/* Wild guesses to initialize configuration values... */
+	homa->link_mbps = 25000;
+	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->pacer_kthread = kthread_run(homa_pacer_main, homa,
+					  "homa_pacer");
+	if (IS_ERR(homa->pacer_kthread)) {
+		err = PTR_ERR(homa->pacer_kthread);
+		homa->pacer_kthread = NULL;
+		pr_err("couldn't create homa pacer thread: error %d\n", err);
+		return err;
+	}
+	homa->pacer_exit = false;
+	homa->max_nic_queue_ns = 5000;
+	homa->wmem_max = 100000000;
+	homa->max_gso_size = 10000;
+	homa->bpage_lease_usecs = 10000;
+	return 0;
+}
+
+/**
+ * homa_destroy() -  Destructor for homa objects.
+ * @homa:      Object to destroy.
+ */
+void homa_destroy(struct homa *homa)
+{
+	if (homa->pacer_kthread) {
+		homa_pacer_stop(homa);
+		wait_for_completion(&homa_pacer_kthread_done);
+	}
+
+	/* The order of the following statements matters! */
+	if (homa->port_map) {
+		homa_socktab_destroy(homa->port_map);
+		kfree(homa->port_map);
+		homa->port_map = NULL;
+	}
+	if (homa->peers) {
+		homa_peertab_destroy(homa->peers);
+		kfree(homa->peers);
+		homa->peers = NULL;
+	}
+}
+
+/**
+ * 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 = sched_clock() + ns;
+	while (sched_clock() < end)
+		/* Empty loop body.*/
+		;
+}
+
-- 
2.34.1