new file mode 100644
@@ -0,0 +1,488 @@
+// SPDX-License-Identifier: BSD-2-Clause
+
+/* This file contains functions for managing homa_rpc structs. */
+
+#include "homa_impl.h"
+#include "homa_peer.h"
+#include "homa_pool.h"
+#include "homa_stub.h"
+
+/**
+ * homa_rpc_new_client() - Allocate and construct a client RPC (one that is used
+ * to issue an outgoing request). Doesn't send any packets. Invoked with no
+ * locks held.
+ * @hsk: Socket to which the RPC belongs.
+ * @dest: Address of host (ip and port) to which the RPC will be sent.
+ *
+ * Return: A printer to the newly allocated object, or a negative
+ * errno if an error occurred. The RPC will be locked; the
+ * caller must eventually unlock it.
+ */
+struct homa_rpc *homa_rpc_new_client(struct homa_sock *hsk,
+ const union sockaddr_in_union *dest)
+{
+ struct in6_addr dest_addr_as_ipv6 = canonical_ipv6_addr(dest);
+ struct homa_rpc_bucket *bucket;
+ struct homa_rpc *crpc;
+ int err;
+
+ crpc = kmalloc(sizeof(*crpc), GFP_KERNEL);
+ if (unlikely(!crpc))
+ return ERR_PTR(-ENOMEM);
+
+ /* Initialize fields that don't require the socket lock. */
+ crpc->hsk = hsk;
+ crpc->id = atomic64_fetch_add(2, &hsk->homa->next_outgoing_id);
+ bucket = homa_client_rpc_bucket(hsk, crpc->id);
+ crpc->bucket = bucket;
+ crpc->state = RPC_OUTGOING;
+ atomic_set(&crpc->flags, 0);
+ crpc->peer = homa_peer_find(hsk->homa->peers, &dest_addr_as_ipv6,
+ &hsk->inet);
+ if (IS_ERR(crpc->peer)) {
+ err = PTR_ERR(crpc->peer);
+ goto error;
+ }
+ crpc->dport = ntohs(dest->in6.sin6_port);
+ crpc->completion_cookie = 0;
+ crpc->error = 0;
+ crpc->msgin.length = -1;
+ crpc->msgin.num_bpages = 0;
+ memset(&crpc->msgout, 0, sizeof(crpc->msgout));
+ crpc->msgout.length = -1;
+ INIT_LIST_HEAD(&crpc->ready_links);
+ INIT_LIST_HEAD(&crpc->buf_links);
+ INIT_LIST_HEAD(&crpc->dead_links);
+ crpc->interest = NULL;
+ INIT_LIST_HEAD(&crpc->throttled_links);
+ crpc->silent_ticks = 0;
+ crpc->resend_timer_ticks = hsk->homa->timer_ticks;
+ crpc->done_timer_ticks = 0;
+ crpc->magic = HOMA_RPC_MAGIC;
+ crpc->start_ns = sched_clock();
+
+ /* Initialize fields that require locking. This allows the most
+ * expensive work, such as copying in the message from user space,
+ * to be performed without holding locks. Also, can't hold spin
+ * locks while doing things that could block, such as memory allocation.
+ */
+ homa_bucket_lock(bucket, crpc->id, "homa_rpc_new_client");
+ homa_sock_lock(hsk, "homa_rpc_new_client");
+ if (hsk->shutdown) {
+ homa_sock_unlock(hsk);
+ homa_rpc_unlock(crpc);
+ err = -ESHUTDOWN;
+ goto error;
+ }
+ hlist_add_head(&crpc->hash_links, &bucket->rpcs);
+ list_add_tail_rcu(&crpc->active_links, &hsk->active_rpcs);
+ homa_sock_unlock(hsk);
+
+ __acquire(&crpc->bucket->lock);
+ return crpc;
+
+error:
+ kfree(crpc);
+ return ERR_PTR(err);
+}
+
+/**
+ * homa_rpc_new_server() - Allocate and construct a server RPC (one that is
+ * used to manage an incoming request). If appropriate, the RPC will also
+ * be handed off (we do it here, while we have the socket locked, to avoid
+ * acquiring the socket lock a second time later for the handoff).
+ * @hsk: Socket that owns this RPC.
+ * @source: IP address (network byte order) of the RPC's client.
+ * @h: Header for the first data packet received for this RPC; used
+ * to initialize the RPC.
+ * @created: Will be set to 1 if a new RPC was created and 0 if an
+ * existing RPC was found.
+ *
+ * Return: A pointer to a new RPC, which is locked, or a negative errno
+ * if an error occurred. If there is already an RPC corresponding
+ * to h, then it is returned instead of creating a new RPC.
+ */
+struct homa_rpc *homa_rpc_new_server(struct homa_sock *hsk,
+ const struct in6_addr *source,
+ struct data_header *h, int *created)
+{
+ __u64 id = homa_local_id(h->common.sender_id);
+ struct homa_rpc_bucket *bucket;
+ struct homa_rpc *srpc = NULL;
+ int err;
+
+ /* Lock the bucket, and make sure no-one else has already created
+ * the desired RPC.
+ */
+ bucket = homa_server_rpc_bucket(hsk, id);
+ homa_bucket_lock(bucket, id, "homa_rpc_new_server");
+ hlist_for_each_entry_rcu(srpc, &bucket->rpcs, hash_links) {
+ if (srpc->id == id &&
+ srpc->dport == ntohs(h->common.sport) &&
+ ipv6_addr_equal(&srpc->peer->addr, source)) {
+ /* RPC already exists; just return it instead
+ * of creating a new RPC.
+ */
+ *created = 0;
+ __acquire(&srpc->bucket->lock);
+ return srpc;
+ }
+ }
+
+ /* Initialize fields that don't require the socket lock. */
+ srpc = kmalloc(sizeof(*srpc), GFP_KERNEL);
+ if (!srpc) {
+ err = -ENOMEM;
+ goto error;
+ }
+ srpc->hsk = hsk;
+ srpc->bucket = bucket;
+ srpc->state = RPC_INCOMING;
+ atomic_set(&srpc->flags, 0);
+ srpc->peer = homa_peer_find(hsk->homa->peers, source, &hsk->inet);
+ if (IS_ERR(srpc->peer)) {
+ err = PTR_ERR(srpc->peer);
+ goto error;
+ }
+ srpc->dport = ntohs(h->common.sport);
+ srpc->id = id;
+ srpc->completion_cookie = 0;
+ srpc->error = 0;
+ srpc->msgin.length = -1;
+ srpc->msgin.num_bpages = 0;
+ memset(&srpc->msgout, 0, sizeof(srpc->msgout));
+ srpc->msgout.length = -1;
+ INIT_LIST_HEAD(&srpc->ready_links);
+ INIT_LIST_HEAD(&srpc->buf_links);
+ INIT_LIST_HEAD(&srpc->dead_links);
+ srpc->interest = NULL;
+ INIT_LIST_HEAD(&srpc->throttled_links);
+ srpc->silent_ticks = 0;
+ srpc->resend_timer_ticks = hsk->homa->timer_ticks;
+ srpc->done_timer_ticks = 0;
+ srpc->magic = HOMA_RPC_MAGIC;
+ srpc->start_ns = sched_clock();
+ err = homa_message_in_init(srpc, ntohl(h->message_length));
+ if (err != 0)
+ goto error;
+
+ /* Initialize fields that require socket to be locked. */
+ homa_sock_lock(hsk, "homa_rpc_new_server");
+ if (hsk->shutdown) {
+ homa_sock_unlock(hsk);
+ err = -ESHUTDOWN;
+ goto error;
+ }
+ hlist_add_head(&srpc->hash_links, &bucket->rpcs);
+ list_add_tail_rcu(&srpc->active_links, &hsk->active_rpcs);
+ if (ntohl(h->seg.offset) == 0 && srpc->msgin.num_bpages > 0) {
+ atomic_or(RPC_PKTS_READY, &srpc->flags);
+ homa_rpc_handoff(srpc);
+ }
+ homa_sock_unlock(hsk);
+ *created = 1;
+ __acquire(&srpc->bucket->lock);
+ return srpc;
+
+error:
+ homa_bucket_unlock(bucket, id);
+ kfree(srpc);
+ return ERR_PTR(err);
+}
+
+/**
+ * homa_rpc_acked() - This function is invoked when an ack is received
+ * for an RPC; if the RPC still exists, is freed.
+ * @hsk: Socket on which the ack was received. May or may not correspond
+ * to the RPC, but can sometimes be used to avoid a socket lookup.
+ * @saddr: Source address from which the act was received (the client
+ * note for the RPC)
+ * @ack: Information about an RPC from @saddr that may now be deleted safely.
+ */
+void homa_rpc_acked(struct homa_sock *hsk, const struct in6_addr *saddr,
+ struct homa_ack *ack)
+{
+ __u16 client_port = ntohs(ack->client_port);
+ __u16 server_port = ntohs(ack->server_port);
+ __u64 id = homa_local_id(ack->client_id);
+ struct homa_sock *hsk2 = hsk;
+ struct homa_rpc *rpc;
+
+ if (hsk2->port != server_port) {
+ /* Without RCU, sockets other than hsk can be deleted
+ * out from under us.
+ */
+ rcu_read_lock();
+ hsk2 = homa_sock_find(hsk->homa->port_map, server_port);
+ if (!hsk2)
+ goto done;
+ }
+ rpc = homa_find_server_rpc(hsk2, saddr, client_port, id);
+ if (rpc) {
+ homa_rpc_free(rpc);
+ homa_rpc_unlock(rpc);
+ }
+
+done:
+ if (hsk->port != server_port)
+ rcu_read_unlock();
+}
+
+/**
+ * homa_rpc_free() - Destructor for homa_rpc; will arrange for all resources
+ * associated with the RPC to be released (eventually).
+ * @rpc: Structure to clean up, or NULL. Must be locked. Its socket must
+ * not be locked.
+ */
+void homa_rpc_free(struct homa_rpc *rpc)
+ __acquires(&rpc->hsk->lock)
+ __releases(&rpc->hsk->lock)
+{
+ /* The goal for this function is to make the RPC inaccessible,
+ * so that no other code will ever access it again. However, don't
+ * actually release resources; leave that to homa_rpc_reap, which
+ * runs later. There are two reasons for this. First, releasing
+ * resources may be expensive, so we don't want to keep the caller
+ * waiting; homa_rpc_reap will run in situations where there is time
+ * to spare. Second, there may be other code that currently has
+ * pointers to this RPC but temporarily released the lock (e.g. to
+ * copy data to/from user space). It isn't safe to clean up until
+ * that code has finished its work and released any pointers to the
+ * RPC (homa_rpc_reap will ensure that this has happened). So, this
+ * function should only make changes needed to make the RPC
+ * inaccessible.
+ */
+ if (!rpc || rpc->state == RPC_DEAD)
+ return;
+ rpc->state = RPC_DEAD;
+
+ /* Unlink from all lists, so no-one will ever find this RPC again. */
+ homa_sock_lock(rpc->hsk, "homa_rpc_free");
+ __hlist_del(&rpc->hash_links);
+ list_del_rcu(&rpc->active_links);
+ list_add_tail_rcu(&rpc->dead_links, &rpc->hsk->dead_rpcs);
+ __list_del_entry(&rpc->ready_links);
+ __list_del_entry(&rpc->buf_links);
+ if (rpc->interest) {
+ rpc->interest->reg_rpc = NULL;
+ wake_up_process(rpc->interest->thread);
+ rpc->interest = NULL;
+ }
+
+ if (rpc->msgin.length >= 0) {
+ rpc->hsk->dead_skbs += skb_queue_len(&rpc->msgin.packets);
+ while (1) {
+ struct homa_gap *gap = list_first_entry_or_null(&rpc->msgin.gaps,
+ struct homa_gap, links);
+ if (!gap)
+ break;
+ list_del(&gap->links);
+ kfree(gap);
+ }
+ }
+ rpc->hsk->dead_skbs += rpc->msgout.num_skbs;
+ if (rpc->hsk->dead_skbs > rpc->hsk->homa->max_dead_buffs)
+ /* This update isn't thread-safe; it's just a
+ * statistic so it's OK if updates occasionally get
+ * missed.
+ */
+ rpc->hsk->homa->max_dead_buffs = rpc->hsk->dead_skbs;
+
+ homa_sock_unlock(rpc->hsk);
+ homa_remove_from_throttled(rpc);
+}
+
+/**
+ * homa_rpc_reap() - Invoked to release resources associated with dead
+ * RPCs for a given socket. For a large RPC, it can take a long time to
+ * free all of its packet buffers, so we try to perform this work
+ * off the critical path where it won't delay applications. Each call to
+ * this function does a small chunk of work. See the file reap.txt for
+ * more information.
+ * @hsk: Homa socket that may contain dead RPCs. Must not be locked by the
+ * caller; this function will lock and release.
+ * @count: Number of buffers to free during this call.
+ *
+ * Return: A return value of 0 means that we ran out of work to do; calling
+ * again will do no work (there could be unreaped RPCs, but if so,
+ * reaping has been disabled for them). A value greater than
+ * zero means there is still more reaping work to be done.
+ */
+int homa_rpc_reap(struct homa_sock *hsk, int count)
+{
+#define BATCH_MAX 20
+ struct homa_rpc *rpcs[BATCH_MAX];
+ struct sk_buff *skbs[BATCH_MAX];
+ int num_skbs, num_rpcs;
+ struct homa_rpc *rpc;
+ int i, batch_size;
+ int rx_frees = 0;
+ int result;
+
+ /* Each iteration through the following loop will reap
+ * BATCH_MAX skbs.
+ */
+ while (count > 0) {
+ batch_size = count;
+ if (batch_size > BATCH_MAX)
+ batch_size = BATCH_MAX;
+ count -= batch_size;
+ num_skbs = 0;
+ num_rpcs = 0;
+
+ homa_sock_lock(hsk, "homa_rpc_reap");
+ if (atomic_read(&hsk->protect_count)) {
+ homa_sock_unlock(hsk);
+ return 0;
+ }
+
+ /* Collect buffers and freeable RPCs. */
+ list_for_each_entry_rcu(rpc, &hsk->dead_rpcs, dead_links) {
+ if ((atomic_read(&rpc->flags) & RPC_CANT_REAP) ||
+ atomic_read(&rpc->msgout.active_xmits) != 0) {
+ continue;
+ }
+ rpc->magic = 0;
+
+ /* For Tx sk_buffs, collect them here but defer
+ * freeing until after releasing the socket lock.
+ */
+ if (rpc->msgout.length >= 0) {
+ while (rpc->msgout.packets) {
+ skbs[num_skbs] = rpc->msgout.packets;
+ rpc->msgout.packets = homa_get_skb_info(rpc
+ ->msgout.packets)->next_skb;
+ num_skbs++;
+ rpc->msgout.num_skbs--;
+ if (num_skbs >= batch_size)
+ goto release;
+ }
+ }
+
+ /* In the normal case rx sk_buffs will already have been
+ * freed before we got here. Thus it's OK to free
+ * immediately in rare situations where there are
+ * buffers left.
+ */
+ if (rpc->msgin.length >= 0) {
+ while (1) {
+ struct sk_buff *skb;
+
+ skb = skb_dequeue(&rpc->msgin.packets);
+ if (!skb)
+ break;
+ kfree_skb(skb);
+ rx_frees++;
+ }
+ }
+
+ /* If we get here, it means all packets have been
+ * removed from the RPC.
+ */
+ rpcs[num_rpcs] = rpc;
+ num_rpcs++;
+ list_del_rcu(&rpc->dead_links);
+ if (num_rpcs >= batch_size)
+ goto release;
+ }
+
+ /* Free all of the collected resources; release the socket
+ * lock while doing this.
+ */
+release:
+ hsk->dead_skbs -= num_skbs + rx_frees;
+ result = !list_empty(&hsk->dead_rpcs) &&
+ (num_skbs + num_rpcs) != 0;
+ homa_sock_unlock(hsk);
+ homa_skb_free_many_tx(hsk->homa, skbs, num_skbs);
+ for (i = 0; i < num_rpcs; i++) {
+ rpc = rpcs[i];
+ /* Lock and unlock the RPC before freeing it. This
+ * is needed to deal with races where the code
+ * that invoked homa_rpc_free hasn't unlocked the
+ * RPC yet.
+ */
+ homa_rpc_lock(rpc, "homa_rpc_reap");
+ homa_rpc_unlock(rpc);
+
+ if (unlikely(rpc->msgin.num_bpages))
+ homa_pool_release_buffers(rpc->hsk->buffer_pool,
+ rpc->msgin.num_bpages,
+ rpc->msgin.bpage_offsets);
+ if (rpc->msgin.length >= 0) {
+ while (1) {
+ struct homa_gap *gap = list_first_entry_or_null(&rpc
+ ->msgin.gaps,
+ struct homa_gap, links);
+ if (!gap)
+ break;
+ list_del(&gap->links);
+ kfree(gap);
+ }
+ }
+ rpc->state = 0;
+ kfree(rpc);
+ }
+ if (!result)
+ break;
+ }
+ homa_pool_check_waiting(hsk->buffer_pool);
+ return result;
+}
+
+/**
+ * homa_find_client_rpc() - Locate client-side information about the RPC that
+ * a packet belongs to, if there is any. Thread-safe without socket lock.
+ * @hsk: Socket via which packet was received.
+ * @id: Unique identifier for the RPC.
+ *
+ * Return: A pointer to the homa_rpc for this id, or NULL if none.
+ * The RPC will be locked; the caller must eventually unlock it
+ * by invoking homa_rpc_unlock.
+ */
+struct homa_rpc *homa_find_client_rpc(struct homa_sock *hsk, __u64 id)
+{
+ struct homa_rpc_bucket *bucket = homa_client_rpc_bucket(hsk, id);
+ struct homa_rpc *crpc;
+
+ homa_bucket_lock(bucket, id, __func__);
+ hlist_for_each_entry_rcu(crpc, &bucket->rpcs, hash_links) {
+ if (crpc->id == id) {
+ __acquire(&crpc->bucket->lock);
+ return crpc;
+ }
+ }
+ homa_bucket_unlock(bucket, id);
+ return NULL;
+}
+
+/**
+ * homa_find_server_rpc() - Locate server-side information about the RPC that
+ * a packet belongs to, if there is any. Thread-safe without socket lock.
+ * @hsk: Socket via which packet was received.
+ * @saddr: Address from which the packet was sent.
+ * @sport: Port at @saddr from which the packet was sent.
+ * @id: Unique identifier for the RPC (must have server bit set).
+ *
+ * Return: A pointer to the homa_rpc matching the arguments, or NULL
+ * if none. The RPC will be locked; the caller must eventually
+ * unlock it by invoking homa_rpc_unlock.
+ */
+struct homa_rpc *homa_find_server_rpc(struct homa_sock *hsk,
+ const struct in6_addr *saddr, __u16 sport,
+ __u64 id)
+{
+ struct homa_rpc_bucket *bucket = homa_server_rpc_bucket(hsk, id);
+ struct homa_rpc *srpc;
+
+ homa_bucket_lock(bucket, id, __func__);
+ hlist_for_each_entry_rcu(srpc, &bucket->rpcs, hash_links) {
+ if (srpc->id == id && srpc->dport == sport &&
+ ipv6_addr_equal(&srpc->peer->addr, saddr)) {
+ __acquire(&srpc->bucket->lock);
+ return srpc;
+ }
+ }
+ homa_bucket_unlock(bucket, id);
+ return NULL;
+}
new file mode 100644
@@ -0,0 +1,446 @@
+/* SPDX-License-Identifier: BSD-2-Clause */
+
+/* This file defines homa_rpc and related structs. */
+
+#ifndef _HOMA_RPC_H
+#define _HOMA_RPC_H
+
+#include <linux/percpu-defs.h>
+#include <linux/skbuff.h>
+#include <linux/types.h>
+
+#include "homa_sock.h"
+#include "homa_wire.h"
+
+/* Forward references. */
+struct homa_ack;
+
+/**
+ * struct homa_message_out - Describes a message (either request or response)
+ * for which this machine is the sender.
+ */
+struct homa_message_out {
+ /**
+ * @length: Total bytes in message (excluding headers). A value
+ * less than 0 means this structure is uninitialized and therefore
+ * not in use (all other fields will be zero in this case).
+ */
+ int length;
+
+ /** @num_skbs: Total number of buffers currently in @packets. */
+ int num_skbs;
+
+ /**
+ * @copied_from_user: Number of bytes of the message that have
+ * been copied from user space into skbs in @packets.
+ */
+ int copied_from_user;
+
+ /**
+ * @packets: Singly-linked list of all packets in message, linked
+ * using homa_next_skb. The list is in order of offset in the message
+ * (offset 0 first); each sk_buff can potentially contain multiple
+ * data_segments, which will be split into separate packets by GSO.
+ * This list grows gradually as data is copied in from user space,
+ * so it may not be complete.
+ */
+ struct sk_buff *packets;
+
+ /**
+ * @next_xmit: Pointer to pointer to next packet to transmit (will
+ * either refer to @packets or homa_next_skb(skb) for some skb
+ * in @packets).
+ */
+ struct sk_buff **next_xmit;
+
+ /**
+ * @next_xmit_offset: All bytes in the message, up to but not
+ * including this one, have been transmitted.
+ */
+ int next_xmit_offset;
+
+ /**
+ * @active_xmits: The number of threads that are currently
+ * transmitting data packets for this RPC; can't reap the RPC
+ * until this count becomes zero.
+ */
+ atomic_t active_xmits;
+
+ /**
+ * @init_ns: Time in sched_clock units when this structure was
+ * initialized. Used to find the oldest outgoing message.
+ */
+ __u64 init_ns;
+};
+
+/**
+ * struct homa_gap - Represents a range of bytes within a message that have
+ * not yet been received.
+ */
+struct homa_gap {
+ /** @start: offset of first byte in this gap. */
+ int start;
+
+ /** @end: offset of byte just after last one in this gap. */
+ int end;
+
+ /**
+ * @time: time (in sched_clock units) when the gap was first detected.
+ * As of 7/2024 this isn't used for anything.
+ */
+ __u64 time;
+
+ /** @links: for linking into list in homa_message_in. */
+ struct list_head links;
+};
+
+/**
+ * struct homa_message_in - Holds the state of a message received by
+ * this machine; used for both requests and responses.
+ */
+struct homa_message_in {
+ /**
+ * @length: Payload size in bytes. A value less than 0 means this
+ * structure is uninitialized and therefore not in use.
+ */
+ int length;
+
+ /**
+ * @packets: DATA packets for this message that have been received but
+ * not yet copied to user space (no particular order).
+ */
+ struct sk_buff_head packets;
+
+ /**
+ * @recv_end: Offset of the byte just after the highest one that
+ * has been received so far.
+ */
+ int recv_end;
+
+ /**
+ * @gaps: List of homa_gaps describing all of the bytes with
+ * offsets less than @recv_end that have not yet been received.
+ */
+ struct list_head gaps;
+
+ /**
+ * @bytes_remaining: Amount of data for this message that has
+ * not yet been received; will determine the message's priority.
+ */
+ int bytes_remaining;
+
+ /** @resend_all: if nonzero, set resend_all in the next grant packet. */
+ __u8 resend_all;
+
+ /**
+ * @num_bpages: The number of entries in @bpage_offsets used for this
+ * message (0 means buffers not allocated yet).
+ */
+ __u32 num_bpages;
+
+ /** @bpage_offsets: Describes buffer space allocated for this message.
+ * Each entry is an offset from the start of the buffer region.
+ * All but the last pointer refer to areas of size HOMA_BPAGE_SIZE.
+ */
+ __u32 bpage_offsets[HOMA_MAX_BPAGES];
+};
+
+/**
+ * struct homa_rpc - One of these structures exists for each active
+ * RPC. The same structure is used to manage both outgoing RPCs on
+ * clients and incoming RPCs on servers.
+ */
+struct homa_rpc {
+ /** @hsk: Socket that owns the RPC. */
+ struct homa_sock *hsk;
+
+ /** @bucket: Pointer to the bucket in hsk->client_rpc_buckets or
+ * hsk->server_rpc_buckets where this RPC is linked. Used primarily
+ * for locking the RPC (which is done by locking its bucket).
+ */
+ struct homa_rpc_bucket *bucket;
+
+ /**
+ * @state: The current state of this RPC:
+ *
+ * @RPC_OUTGOING: The RPC is waiting for @msgout to be transmitted
+ * to the peer.
+ * @RPC_INCOMING: The RPC is waiting for data @msgin to be received
+ * from the peer; at least one packet has already
+ * been received.
+ * @RPC_IN_SERVICE: Used only for server RPCs: the request message
+ * has been read from the socket, but the response
+ * message has not yet been presented to the kernel.
+ * @RPC_DEAD: RPC has been deleted and is waiting to be
+ * reaped. In some cases, information in the RPC
+ * structure may be accessed in this state.
+ *
+ * Client RPCs pass through states in the following order:
+ * RPC_OUTGOING, RPC_INCOMING, RPC_DEAD.
+ *
+ * Server RPCs pass through states in the following order:
+ * RPC_INCOMING, RPC_IN_SERVICE, RPC_OUTGOING, RPC_DEAD.
+ */
+ enum {
+ RPC_OUTGOING = 5,
+ RPC_INCOMING = 6,
+ RPC_IN_SERVICE = 8,
+ RPC_DEAD = 9
+ } state;
+
+ /**
+ * @flags: Additional state information: an OR'ed combination of
+ * various single-bit flags. See below for definitions. Must be
+ * manipulated with atomic operations because some of the manipulations
+ * occur without holding the RPC lock.
+ */
+ atomic_t flags;
+
+ /* Valid bits for @flags:
+ * RPC_PKTS_READY - The RPC has input packets ready to be
+ * copied to user space.
+ * RPC_COPYING_FROM_USER - Data is being copied from user space into
+ * the RPC; the RPC must not be reaped.
+ * RPC_COPYING_TO_USER - Data is being copied from this RPC to
+ * user space; the RPC must not be reaped.
+ * RPC_HANDING_OFF - This RPC is in the process of being
+ * handed off to a waiting thread; it must
+ * not be reaped.
+ * APP_NEEDS_LOCK - Means that code in the application thread
+ * needs the RPC lock (e.g. so it can start
+ * copying data to user space) so others
+ * (e.g. SoftIRQ processing) should relinquish
+ * the lock ASAP. Without this, SoftIRQ can
+ * lock out the application for a long time,
+ * preventing data copies to user space from
+ * starting (and they limit throughput at
+ * high network speeds).
+ */
+#define RPC_PKTS_READY 1
+#define RPC_COPYING_FROM_USER 2
+#define RPC_COPYING_TO_USER 4
+#define RPC_HANDING_OFF 8
+#define APP_NEEDS_LOCK 16
+
+#define RPC_CANT_REAP (RPC_COPYING_FROM_USER | RPC_COPYING_TO_USER \
+ | RPC_HANDING_OFF)
+
+ /**
+ * @peer: Information about the other machine (the server, if
+ * this is a client RPC, or the client, if this is a server RPC).
+ */
+ struct homa_peer *peer;
+
+ /** @dport: Port number on @peer that will handle packets. */
+ __u16 dport;
+
+ /**
+ * @id: Unique identifier for the RPC among all those issued
+ * from its port. The low-order bit indicates whether we are
+ * server (1) or client (0) for this RPC.
+ */
+ __u64 id;
+
+ /**
+ * @completion_cookie: Only used on clients. Contains identifying
+ * information about the RPC provided by the application; returned to
+ * the application with the RPC's result.
+ */
+ __u64 completion_cookie;
+
+ /**
+ * @error: Only used on clients. If nonzero, then the RPC has
+ * failed and the value is a negative errno that describes the
+ * problem.
+ */
+ int error;
+
+ /**
+ * @msgin: Information about the message we receive for this RPC
+ * (for server RPCs this is the request, for client RPCs this is the
+ * response).
+ */
+ struct homa_message_in msgin;
+
+ /**
+ * @msgout: Information about the message we send for this RPC
+ * (for client RPCs this is the request, for server RPCs this is the
+ * response).
+ */
+ struct homa_message_out msgout;
+
+ /**
+ * @hash_links: Used to link this object into a hash bucket for
+ * either @hsk->client_rpc_buckets (for a client RPC), or
+ * @hsk->server_rpc_buckets (for a server RPC).
+ */
+ struct hlist_node hash_links;
+
+ /**
+ * @ready_links: Used to link this object into
+ * @hsk->ready_requests or @hsk->ready_responses.
+ */
+ struct list_head ready_links;
+
+ /**
+ * @buf_links: Used to link this RPC into @hsk->waiting_for_bufs.
+ * If the RPC isn't on @hsk->waiting_for_bufs, this is an empty
+ * list pointing to itself.
+ */
+ struct list_head buf_links;
+
+ /**
+ * @active_links: For linking this object into @hsk->active_rpcs.
+ * The next field will be LIST_POISON1 if this RPC hasn't yet been
+ * linked into @hsk->active_rpcs. Access with RCU.
+ */
+ struct list_head active_links;
+
+ /** @dead_links: For linking this object into @hsk->dead_rpcs. */
+ struct list_head dead_links;
+
+ /**
+ * @interest: Describes a thread that wants to be notified when
+ * msgin is complete, or NULL if none.
+ */
+ struct homa_interest *interest;
+
+ /**
+ * @throttled_links: Used to link this RPC into homa->throttled_rpcs.
+ * If this RPC isn't in homa->throttled_rpcs, this is an empty
+ * list pointing to itself.
+ */
+ struct list_head throttled_links;
+
+ /**
+ * @silent_ticks: Number of times homa_timer has been invoked
+ * since the last time a packet indicating progress was received
+ * for this RPC, so we don't need to send a resend for a while.
+ */
+ int silent_ticks;
+
+ /**
+ * @resend_timer_ticks: Value of homa->timer_ticks the last time
+ * we sent a RESEND for this RPC.
+ */
+ __u32 resend_timer_ticks;
+
+ /**
+ * @done_timer_ticks: The value of homa->timer_ticks the first
+ * time we noticed that this (server) RPC is done (all response
+ * packets have been transmitted), so we're ready for an ack.
+ * Zero means we haven't reached that point yet.
+ */
+ __u32 done_timer_ticks;
+
+ /**
+ * @magic: when the RPC is alive, this holds a distinct value that
+ * is unlikely to occur naturally. The value is cleared when the
+ * RPC is reaped, so we can detect accidental use of an RPC after
+ * it has been reaped.
+ */
+#define HOMA_RPC_MAGIC 0xdeadbeef
+ int magic;
+
+ /**
+ * @start_ns: time (from sched_clock()) when this RPC was created.
+ * Used (sometimes) for testing.
+ */
+ u64 start_ns;
+};
+
+void homa_check_rpc(struct homa_rpc *rpc);
+struct homa_rpc *homa_find_client_rpc(struct homa_sock *hsk, __u64 id);
+struct homa_rpc *homa_find_server_rpc(struct homa_sock *hsk,
+ const struct in6_addr *saddr, __u16 sport,
+ __u64 id);
+void homa_rpc_acked(struct homa_sock *hsk,
+ const struct in6_addr *saddr,
+ struct homa_ack *ack);
+void homa_rpc_free(struct homa_rpc *rpc);
+struct homa_rpc *homa_rpc_new_client(struct homa_sock *hsk,
+ const union sockaddr_in_union *dest);
+struct homa_rpc *homa_rpc_new_server(struct homa_sock *hsk,
+ const struct in6_addr *source,
+ struct data_header *h,
+ int *created);
+int homa_rpc_reap(struct homa_sock *hsk, int count);
+
+/**
+ * homa_rpc_lock() - Acquire the lock for an RPC.
+ * @rpc: RPC to lock. Note: this function is only safe under
+ * limited conditions (in most cases homa_bucket_lock should be
+ * used). The caller must ensure that the RPC cannot be reaped
+ * before the lock is acquired. It cannot do that by acquirin
+ * the socket lock, since that violates lock ordering constraints.
+ * One approach is to use homa_protect_rpcs. Don't use this function
+ * unless you are very sure what you are doing! See sync.txt for
+ * more info on locking.
+ * @locker: Static string identifying the locking code. Normally ignored,
+ * but used occasionally for diagnostics and debugging.
+ */
+// static inline void homa_rpc_lock(struct homa_rpc *rpc, const char *locker)
+// __acquires(&rpc->bucket->lock)
+// {
+// homa_bucket_lock(rpc->bucket, rpc->id, locker);
+// }
+
+#define homa_rpc_lock(rpc, locker) do { \
+ struct homa_rpc *_rpc = rpc; \
+ homa_bucket_lock(_rpc->bucket, _rpc->id, locker); \
+} while (0)
+
+/**
+ * homa_rpc_unlock() - Release the lock for an RPC.
+ * @rpc: RPC to unlock.
+ */
+static inline void homa_rpc_unlock(struct homa_rpc *rpc)
+ __releases(&rpc->bucket->lock)
+{
+ homa_bucket_unlock(rpc->bucket, rpc->id);
+}
+
+/**
+ * homa_protect_rpcs() - Ensures that no RPCs will be reaped for a given
+ * socket until homa_sock_unprotect is called. Typically used by functions
+ * that want to scan the active RPCs for a socket without holding the socket
+ * lock. Multiple calls to this function may be in effect at once.
+ * @hsk: Socket whose RPCs should be protected. Must not be locked
+ * by the caller; will be locked here.
+ *
+ * Return: 1 for success, 0 if the socket has been shutdown, in which
+ * case its RPCs cannot be protected.
+ */
+static inline int homa_protect_rpcs(struct homa_sock *hsk)
+{
+ int result;
+
+ homa_sock_lock(hsk, __func__);
+ result = !hsk->shutdown;
+ if (result)
+ atomic_inc(&hsk->protect_count);
+ homa_sock_unlock(hsk);
+ return result;
+}
+
+/**
+ * homa_unprotect_rpcs() - Cancel the effect of a previous call to
+ * homa_sock_protect(), so that RPCs can once again be reaped.
+ * @hsk: Socket whose RPCs should be unprotected.
+ */
+static inline void homa_unprotect_rpcs(struct homa_sock *hsk)
+{
+ atomic_dec(&hsk->protect_count);
+}
+
+/**
+ * homa_is_client(): returns true if we are the client for a particular RPC,
+ * false if we are the server.
+ * @id: Id of the RPC in question.
+ */
+static inline bool homa_is_client(__u64 id)
+{
+ return (id & 1) == 0;
+}
+
+#endif /* _HOMA_RPC_H */
These files provide basic functions for managing remote procedure calls, which are the fundamental entities managed by Homa. Each RPC consists of a request message from a client to a server, followed by a response message returned from the server to the client. Signed-off-by: John Ousterhout <ouster@cs.stanford.edu> --- net/homa/homa_rpc.c | 488 ++++++++++++++++++++++++++++++++++++++++++++ net/homa/homa_rpc.h | 446 ++++++++++++++++++++++++++++++++++++++++ 2 files changed, 934 insertions(+) create mode 100644 net/homa/homa_rpc.c create mode 100644 net/homa/homa_rpc.h