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homa_incoming.c
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homa_incoming.c
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// SPDX-License-Identifier: BSD-2-Clause
/* This file contains functions that handle incoming Homa messages, including
* both receiving information for those messages and sending grants.
*/
#include "homa_impl.h"
#include "homa_grant.h"
#include "homa_offload.h"
#include "homa_peer.h"
#include "homa_pool.h"
/**
* homa_message_in_init() - Constructor for homa_message_in.
* @rpc: RPC whose msgin structure should be initialized.
* @length: Total number of bytes in message.
* @unsched: The number of unscheduled bytes the sender is planning
* to transmit.
* Return: Zero for successful initialization, or a negative errno
* if rpc->msgin could not be initialized.
*/
int homa_message_in_init(struct homa_rpc *rpc, int length, int unsched)
{
int err;
rpc->msgin.length = length;
skb_queue_head_init(&rpc->msgin.packets);
rpc->msgin.recv_end = 0;
INIT_LIST_HEAD(&rpc->msgin.gaps);
rpc->msgin.bytes_remaining = length;
rpc->msgin.granted = (unsched > length) ? length : unsched;
rpc->msgin.rec_incoming = 0;
atomic_set(&rpc->msgin.rank, -1);
rpc->msgin.priority = 0;
rpc->msgin.resend_all = 0;
rpc->msgin.num_bpages = 0;
err = homa_pool_allocate(rpc);
if (err != 0)
return err;
if (rpc->msgin.num_bpages == 0) {
/* The RPC is now queued waiting for buffer space, so we're
* going to discard all of its packets.
*/
rpc->msgin.granted = 0;
}
if (length < HOMA_NUM_SMALL_COUNTS*64) {
INC_METRIC(small_msg_bytes[(length-1) >> 6], length);
} else if (length < HOMA_NUM_MEDIUM_COUNTS*1024) {
INC_METRIC(medium_msg_bytes[(length-1) >> 10], length);
} else {
INC_METRIC(large_msg_count, 1);
INC_METRIC(large_msg_bytes, length);
}
return 0;
}
/**
* homa_gap_new() - Create a new gap and add it to a list.
* @next: Add the new gap just before this list element.
* @start: Offset of first byte covered by the gap.
* @end: Offset of byte just after the last one covered by the gap.
* Return: Pointer to the new gap.
*/
struct homa_gap *homa_gap_new(struct list_head *next, int start, int end)
{
struct homa_gap *gap;
gap = kmalloc(sizeof(struct homa_gap), GFP_KERNEL);
gap->start = start;
gap->end = end;
gap->time = get_cycles();
list_add_tail(&gap->links, next);
return gap;
}
/**
* homa_gap_retry() - Send RESEND requests for all of the unreceived
* gaps in a message.
* @rpc: RPC to check; must be locked by caller.
*/
void homa_gap_retry(struct homa_rpc *rpc)
{
struct homa_gap *gap;
struct resend_header resend;
list_for_each_entry(gap, &rpc->msgin.gaps, links) {
resend.offset = htonl(gap->start);
resend.length = htonl(gap->end - gap->start);
resend.priority = rpc->hsk->homa->num_priorities - 1;
tt_record3("homa_gap_retry sending RESEND for id %d, start %d, end %d",
rpc->id, gap->start, gap->end);
homa_xmit_control(RESEND, &resend, sizeof(resend), rpc);
}
}
/**
* homa_add_packet() - Add an incoming packet to the contents of a
* partially received message.
* @rpc: Add the packet to the msgin for this RPC.
* @skb: The new packet. This function takes ownership of the packet
* (the packet will either be freed or added to rpc->msgin.packets).
*/
void homa_add_packet(struct homa_rpc *rpc, struct sk_buff *skb)
{
struct data_header *h = (struct data_header *) skb->data;
int start = ntohl(h->seg.offset);
int length = homa_data_len(skb);
int end = start + length;
struct homa_gap *gap, *dummy, *gap2;
if ((start + length) > rpc->msgin.length) {
tt_record3("Packet extended past message end; id %d, offset %d, length %d",
rpc->id, start, length);
goto discard;
}
if (start == rpc->msgin.recv_end) {
/* Common case: packet is sequential. */
rpc->msgin.recv_end += length;
goto keep;
}
if (start > rpc->msgin.recv_end) {
/* Packet creates a new gap. */
homa_gap_new(&rpc->msgin.gaps, rpc->msgin.recv_end, start);
rpc->msgin.recv_end = end;
goto keep;
}
/* Must now check to see if the packet fills in part or all of
* an existing gap.
*/
list_for_each_entry_safe(gap, dummy, &rpc->msgin.gaps, links) {
/* Is packet at the start of this gap? */
if (start <= gap->start) {
if (end <= gap->start)
continue;
if (start < gap->start) {
tt_record4("Packet overlaps gap start: id %d, start %d, end %d, gap_start %d",
rpc->id, start, end, gap->start);
goto discard;
}
if (end > gap->end) {
tt_record4("Packet overlaps gap end: id %d, start %d, end %d, gap_end %d",
rpc->id, start, end, gap->start);
goto discard;
}
gap->start = end;
if (gap->start >= gap->end) {
list_del(&gap->links);
kfree(gap);
}
goto keep;
}
/* Is packet at the end of this gap? BTW, at this point we know
* the packet can't cover the entire gap.
*/
if (end >= gap->end) {
if (start >= gap->end)
continue;
if (end > gap->end) {
tt_record4("Packet overlaps gap end: id %d, start %d, end %d, gap_end %d",
rpc->id, start, end, gap->start);
goto discard;
}
gap->end = start;
goto keep;
}
/* Packet is in the middle of the gap; must split the gap. */
gap2 = homa_gap_new(&gap->links, gap->start, start);
gap2->time = gap->time;
gap->start = end;
goto keep;
}
discard:
if (h->retransmit)
INC_METRIC(resent_discards, 1);
else
INC_METRIC(packet_discards, 1);
tt_record4("homa_add_packet discarding packet for id %d, offset %d, length %d, retransmit %d",
rpc->id, start, length, h->retransmit);
kfree_skb(skb);
return;
keep:
if (h->retransmit)
INC_METRIC(resent_packets_used, 1);
__skb_queue_tail(&rpc->msgin.packets, skb);
rpc->msgin.bytes_remaining -= length;
}
/**
* homa_copy_to_user() - Copy as much data as possible from incoming
* packet buffers to buffers in user space.
* @rpc: RPC for which data should be copied. Must be locked by caller.
* Return: Zero for success or a negative errno if there is an error.
* It is possible for the RPC to be freed while this function
* executes (it releases and reacquires the RPC lock). If that
* happens, -EINVAL will be returned and the state of @rpc
* will be RPC_DEAD.
*/
int homa_copy_to_user(struct homa_rpc *rpc)
{
#ifdef __UNIT_TEST__
#define MAX_SKBS 3
#else
#define MAX_SKBS 20
#endif
struct sk_buff *skbs[MAX_SKBS];
int n = 0; /* Number of filled entries in skbs. */
int error = 0;
int start_offset = 0;
int end_offset = 0;
int i;
__u64 start;
/* Tricky note: we can't hold the RPC lock while we're actually
* copying to user space, because (a) it's illegal to hold a spinlock
* while copying to user space and (b) we'd like for homa_softirq
* to add more packets to the RPC while we're copying these out.
* So, collect a bunch of packets to copy, then release the lock,
* copy them, and reacquire the lock.
*/
while (true) {
struct sk_buff *skb;
if (rpc->state == RPC_DEAD) {
error = -EINVAL;
break;
}
skb = __skb_dequeue(&rpc->msgin.packets);
if (skb != NULL) {
skbs[n] = skb;
n++;
if (n < MAX_SKBS)
continue;
}
if (n == 0)
break;
/* At this point we've collected a batch of packets (or
* run out of packets); copy any available packets out to
* user space.
*/
atomic_or(RPC_COPYING_TO_USER, &rpc->flags);
homa_rpc_unlock(rpc);
tt_record1("starting copy to user space for id %d",
rpc->id);
/* Each iteration of this loop copies out one skb. */
for (i = 0; i < n; i++) {
struct data_header *h = (struct data_header *)
skbs[i]->data;
int offset = ntohl(h->seg.offset);
int pkt_length = homa_data_len(skbs[i]);
int copied = 0;
char *dst;
struct iov_iter iter;
int buf_bytes, chunk_size;
/* Each iteration of this loop copies to one
* user buffer.
*/
while (copied < pkt_length) {
chunk_size = pkt_length - copied;
dst = homa_pool_get_buffer(rpc, offset + copied,
&buf_bytes);
if (buf_bytes < chunk_size) {
if (buf_bytes == 0) {
/* skb has data beyond message
* end?
*/
break;
}
chunk_size = buf_bytes;
}
error = import_ubuf(READ, dst, chunk_size,
&iter);
if (error)
goto free_skbs;
error = skb_copy_datagram_iter(skbs[i],
sizeof(*h) + copied, &iter,
chunk_size);
if (error)
goto free_skbs;
copied += chunk_size;
}
if (end_offset == 0) {
start_offset = offset;
} else if (end_offset != offset) {
tt_record3("copied out bytes %d-%d for id %d",
start_offset, end_offset,
rpc->id);
start_offset = offset;
}
end_offset = offset + pkt_length;
}
free_skbs:
if (end_offset != 0) {
tt_record3("copied out bytes %d-%d for id %d",
start_offset, end_offset, rpc->id);
end_offset = 0;
}
start = get_cycles();
for (i = 0; i < n; i++)
kfree_skb(skbs[i]);
INC_METRIC(skb_free_cycles, get_cycles() - start);
INC_METRIC(skb_frees, n);
tt_record2("finished freeing %d skbs for id %d",
n, rpc->id);
n = 0;
atomic_or(APP_NEEDS_LOCK, &rpc->flags);
homa_rpc_lock(rpc, "homa_copy_to_user");
atomic_andnot(APP_NEEDS_LOCK|RPC_COPYING_TO_USER, &rpc->flags);
if (error)
break;
}
if (error)
tt_record2("homa_copy_to_user returning error %d for id %d",
-error, rpc->id);
return error;
}
/**
* homa_dispatch_pkts() - Top-level function that processes a batch of packets,
* all related to the same RPC.
* @skb: First packet in the batch, linked through skb->next.
* @homa: Overall information about the Homa transport.
*/
void homa_dispatch_pkts(struct sk_buff *skb, struct homa *homa)
{
const struct in6_addr saddr = skb_canonical_ipv6_saddr(skb);
struct data_header *h = (struct data_header *) skb->data;
__u64 id = homa_local_id(h->common.sender_id);
int dport = ntohs(h->common.dport);
struct homa_sock *hsk;
struct homa_rpc *rpc = NULL;
struct sk_buff *next;
#ifdef __UNIT_TEST__
#define MAX_ACKS 2
#else
#define MAX_ACKS 10
#endif
/* Used to collect acks from data packets so we can process them
* all at the end (can't process them inline because that may
* require locking conflicting RPCs). If we run out of space just
* ignore the extra acks; they'll be regenerated later through the
* explicit mechanism.
*/
struct homa_ack acks[MAX_ACKS];
int num_acks = 0;
/* Find the appropriate socket.*/
hsk = homa_sock_find(homa->port_map, dport);
if (!hsk) {
if (skb_is_ipv6(skb))
icmp6_send(skb, ICMPV6_DEST_UNREACH,
ICMPV6_PORT_UNREACH, 0, NULL,
IP6CB(skb));
else
icmp_send(skb, ICMP_DEST_UNREACH,
ICMP_PORT_UNREACH, 0);
tt_record3("Discarding packet(s) for unknown port %u, id %llu, type %d",
dport, homa_local_id(h->common.sender_id),
h->common.type);
while (skb != NULL) {
next = skb->next;
kfree_skb(skb);
skb = next;
}
return;
}
/* Each iteration through the following loop processes one packet. */
for (; skb != NULL; skb = next) {
h = (struct data_header *) skb->data;
next = skb->next;
/* Relinquish the RPC lock temporarily if it's needed
* elsewhere.
*/
if (rpc != NULL) {
int flags = atomic_read(&rpc->flags);
if (flags & APP_NEEDS_LOCK) {
homa_rpc_unlock(rpc);
tt_record2("softirq released lock for id %d, flags 0x%x", rpc->id, flags);
homa_spin(200);
rpc = NULL;
}
}
/* Find and lock the RPC if we haven't already done so. */
if (rpc == NULL) {
if (!homa_is_client(id)) {
/* We are the server for this RPC. */
if (h->common.type == DATA) {
int created;
/* Create a new RPC if one doesn't
* already exist.
*/
rpc = homa_rpc_new_server(hsk, &saddr,
h, &created);
if (IS_ERR(rpc)) {
pr_warn("homa_pkt_dispatch couldn't create server rpc: error %lu",
-PTR_ERR(rpc));
INC_METRIC(server_cant_create_rpcs, 1);
rpc = NULL;
goto discard;
}
} else
rpc = homa_find_server_rpc(hsk, &saddr,
ntohs(h->common.sport),
id);
} else {
rpc = homa_find_client_rpc(hsk, id);
}
}
if (unlikely(!rpc)) {
if ((h->common.type != CUTOFFS)
&& (h->common.type != NEED_ACK)
&& (h->common.type != ACK)
&& (h->common.type != RESEND)) {
tt_record4("Discarding packet for unknown RPC, id %u, type %d, peer 0x%x:%d",
id, h->common.type,
tt_addr(saddr),
ntohs(h->common.sport));
if ((h->common.type != GRANT) || homa_is_client(id))
INC_METRIC(unknown_rpcs, 1);
goto discard;
}
} else {
if ((h->common.type == DATA) || (h->common.type == GRANT)
|| (h->common.type == BUSY))
rpc->silent_ticks = 0;
rpc->peer->outstanding_resends = 0;
}
switch (h->common.type) {
case DATA:
if (h->ack.client_id != 0) {
/* Save the ack for processing later, when we
* have released the RPC lock.
*/
if (num_acks < MAX_ACKS) {
acks[num_acks] = h->ack;
num_acks++;
}
}
homa_data_pkt(skb, rpc);
INC_METRIC(packets_received[DATA - DATA], 1);
break;
case GRANT:
INC_METRIC(packets_received[GRANT - DATA], 1);
homa_grant_pkt(skb, rpc);
break;
case RESEND:
INC_METRIC(packets_received[RESEND - DATA], 1);
homa_resend_pkt(skb, rpc, hsk);
break;
case UNKNOWN:
INC_METRIC(packets_received[UNKNOWN - DATA], 1);
homa_unknown_pkt(skb, rpc);
break;
case BUSY:
INC_METRIC(packets_received[BUSY - DATA], 1);
tt_record2("received BUSY for id %d, peer 0x%x",
id, tt_addr(rpc->peer->addr));
/* Nothing to do for these packets except reset
* silent_ticks, which happened above.
*/
goto discard;
case CUTOFFS:
INC_METRIC(packets_received[CUTOFFS - DATA], 1);
homa_cutoffs_pkt(skb, hsk);
break;
case NEED_ACK:
INC_METRIC(packets_received[NEED_ACK - DATA], 1);
homa_need_ack_pkt(skb, hsk, rpc);
break;
case ACK:
INC_METRIC(packets_received[ACK - DATA], 1);
homa_ack_pkt(skb, hsk, rpc);
rpc = NULL;
/* It isn't safe to process more packets once we've
* released the RPC lock (this should never happen).
*/
BUG_ON(next != NULL);
break;
default:
INC_METRIC(unknown_packet_types, 1);
goto discard;
}
continue;
discard:
kfree_skb(skb);
}
if (rpc != NULL)
homa_grant_check_rpc(rpc);
while (num_acks > 0) {
num_acks--;
homa_rpc_acked(hsk, &saddr, &acks[num_acks]);
}
if (hsk->dead_skbs >= 2*hsk->homa->dead_buffs_limit) {
/* We get here if neither homa_wait_for_message
* nor homa_timer can keep up with reaping dead
* RPCs. See reap.txt for details.
*/
uint64_t start = get_cycles();
tt_record("homa_data_pkt calling homa_rpc_reap");
homa_rpc_reap(hsk, hsk->homa->reap_limit);
INC_METRIC(data_pkt_reap_cycles,
get_cycles() - start);
}
}
/**
* homa_data_pkt() - Handler for incoming DATA packets
* @skb: Incoming packet; size known to be large enough for the header.
* This function now owns the packet.
* @rpc: Information about the RPC corresponding to this packet.
* Must be locked by the caller.
*/
void homa_data_pkt(struct sk_buff *skb, struct homa_rpc *rpc)
{
struct homa *homa = rpc->hsk->homa;
struct data_header *h = (struct data_header *) skb->data;
tt_record4("incoming data packet, id %d, peer 0x%x, offset %d/%d",
homa_local_id(h->common.sender_id),
tt_addr(rpc->peer->addr), ntohl(h->seg.offset),
ntohl(h->message_length));
if ((rpc->state != RPC_INCOMING) && homa_is_client(rpc->id)) {
if (unlikely(rpc->state != RPC_OUTGOING))
goto discard;
INC_METRIC(responses_received, 1);
rpc->state = RPC_INCOMING;
tt_record2("Incoming message for id %d has %d unscheduled bytes",
rpc->id, ntohl(h->incoming));
if (homa_message_in_init(rpc, ntohl(h->message_length),
ntohl(h->incoming)) != 0)
goto discard;
} else if (rpc->state != RPC_INCOMING) {
/* Must be server; note that homa_rpc_new_server already
* initialized msgin and allocated buffers.
*/
if (unlikely(rpc->msgin.length >= 0))
goto discard;
}
if (rpc->msgin.num_bpages == 0) {
/* Drop packets that arrive when we can't allocate buffer
* space. If we keep them around, packet buffer usage can
* exceed available cache space, resulting in poor
* performance.
*/
tt_record4("Dropping packet because no buffer space available: id %d, offset %d, length %d, old incoming %d",
rpc->id, ntohl(h->seg.offset),
homa_data_len(skb),
rpc->msgin.granted);
INC_METRIC(dropped_data_no_bufs, homa_data_len(skb));
goto discard;
}
homa_add_packet(rpc, skb);
if ((skb_queue_len(&rpc->msgin.packets) != 0)
&& !(atomic_read(&rpc->flags) & RPC_PKTS_READY)) {
atomic_or(RPC_PKTS_READY, &rpc->flags);
homa_sock_lock(rpc->hsk, "homa_data_pkt");
homa_rpc_handoff(rpc);
homa_sock_unlock(rpc->hsk);
}
if (ntohs(h->cutoff_version) != homa->cutoff_version) {
/* The sender has out-of-date cutoffs. Note: we may need
* to resend CUTOFFS packets if one gets lost, but we don't
* want to send multiple CUTOFFS packets when a stream of
* packets arrives with stale cutoff_versions. Thus, we
* don't send CUTOFFS unless there is a version mismatch
* *and* it is been a while since the previous CUTOFFS
* packet.
*/
if (jiffies != rpc->peer->last_update_jiffies) {
struct cutoffs_header h2;
int i;
for (i = 0; i < HOMA_MAX_PRIORITIES; i++) {
h2.unsched_cutoffs[i] =
htonl(homa->unsched_cutoffs[i]);
}
h2.cutoff_version = htons(homa->cutoff_version);
homa_xmit_control(CUTOFFS, &h2, sizeof(h2), rpc);
rpc->peer->last_update_jiffies = jiffies;
}
}
return;
discard:
kfree_skb(skb);
UNIT_LOG("; ", "homa_data_pkt discarded packet");
}
/**
* homa_grant_pkt() - Handler for incoming GRANT packets
* @skb: Incoming packet; size already verified large enough for header.
* This function now owns the packet.
* @rpc: Information about the RPC corresponding to this packet.
*/
void homa_grant_pkt(struct sk_buff *skb, struct homa_rpc *rpc)
{
struct grant_header *h = (struct grant_header *) skb->data;
int new_offset = ntohl(h->offset);
tt_record4("processing grant for id %llu, offset %d, priority %d, increment %d",
homa_local_id(h->common.sender_id), ntohl(h->offset),
h->priority, new_offset - rpc->msgout.granted);
if (rpc->state == RPC_OUTGOING) {
if (h->resend_all)
homa_resend_data(rpc, 0, rpc->msgout.next_xmit_offset,
h->priority);
if (new_offset > rpc->msgout.granted) {
rpc->msgout.granted = new_offset;
if (new_offset > rpc->msgout.length)
rpc->msgout.granted = rpc->msgout.length;
}
rpc->msgout.sched_priority = h->priority;
homa_xmit_data(rpc, false);
}
kfree_skb(skb);
}
/**
* homa_resend_pkt() - Handler for incoming RESEND packets
* @skb: Incoming packet; size already verified large enough for header.
* This function now owns the packet.
* @rpc: Information about the RPC corresponding to this packet; must
* be locked by caller, but may be NULL if there is no RPC matching
* this packet
* @hsk: Socket on which the packet was received.
*/
void homa_resend_pkt(struct sk_buff *skb, struct homa_rpc *rpc,
struct homa_sock *hsk)
{
struct resend_header *h = (struct resend_header *) skb->data;
const struct in6_addr saddr = skb_canonical_ipv6_saddr(skb);
struct busy_header busy;
if (rpc == NULL) {
tt_record4("resend request for unknown id %d, peer 0x%x:%d, offset %d; responding with UNKNOWN",
homa_local_id(h->common.sender_id),
tt_addr(saddr), ntohs(h->common.sport),
ntohl(h->offset));
homa_xmit_unknown(skb, hsk);
goto done;
}
tt_record4("resend request for id %llu, offset %d, length %d, prio %d",
rpc->id, ntohl(h->offset), ntohl(h->length),
h->priority);
if (!homa_is_client(rpc->id) && rpc->state != RPC_OUTGOING) {
/* We are the server for this RPC and don't yet have a
* response packet, so just send BUSY.
*/
tt_record2("sending BUSY from resend, id %d, state %d",
rpc->id, rpc->state);
homa_xmit_control(BUSY, &busy, sizeof(busy), rpc);
goto done;
}
if (rpc->msgout.next_xmit_offset < rpc->msgout.granted) {
/* We have chosen not to transmit data from this message;
* send BUSY instead.
*/
tt_record3("sending BUSY from resend, id %d, offset %d, granted %d",
rpc->id, rpc->msgout.next_xmit_offset,
rpc->msgout.granted);
homa_xmit_control(BUSY, &busy, sizeof(busy), rpc);
} else {
if (ntohl(h->length) == 0) {
/* This RESEND is from a server just trying to determine
* whether the client still cares about the RPC; return
* BUSY so the server doesn't time us out.
*/
homa_xmit_control(BUSY, &busy, sizeof(busy), rpc);
}
homa_resend_data(rpc, ntohl(h->offset),
ntohl(h->offset) + ntohl(h->length),
h->priority);
}
done:
kfree_skb(skb);
}
/**
* homa_unknown_pkt() - Handler for incoming UNKNOWN packets.
* @skb: Incoming packet; size known to be large enough for the header.
* This function now owns the packet.
* @rpc: Information about the RPC corresponding to this packet.
*/
void homa_unknown_pkt(struct sk_buff *skb, struct homa_rpc *rpc)
{
tt_record3("Received unknown for id %llu, peer %x:%d",
rpc->id, tt_addr(rpc->peer->addr), rpc->dport);
if (homa_is_client(rpc->id)) {
if (rpc->state == RPC_OUTGOING) {
/* It appears that everything we've already transmitted
* has been lost; retransmit it.
*/
tt_record4("Restarting id %d to server 0x%x:%d, lost %d bytes",
rpc->id, tt_addr(rpc->peer->addr),
rpc->dport,
rpc->msgout.next_xmit_offset);
homa_freeze(rpc, RESTART_RPC, "Freezing because of RPC restart, id %d, peer 0x%x");
homa_resend_data(rpc, 0, rpc->msgout.next_xmit_offset,
homa_unsched_priority(rpc->hsk->homa,
rpc->peer, rpc->msgout.length));
goto done;
}
pr_err("Received unknown for RPC id %llu, peer %s:%d in bogus state %d; discarding unknown\n",
rpc->id, homa_print_ipv6_addr(&rpc->peer->addr),
rpc->dport, rpc->state);
tt_record4("Discarding unknown for RPC id %d, peer 0x%x:%d: bad state %d",
rpc->id, tt_addr(rpc->peer->addr), rpc->dport,
rpc->state);
} else {
if (rpc->hsk->homa->verbose)
pr_notice("Freeing rpc id %llu from client %s:%d: unknown to client",
rpc->id,
homa_print_ipv6_addr(&rpc->peer->addr),
rpc->dport);
homa_rpc_free(rpc);
INC_METRIC(server_rpcs_unknown, 1);
}
done:
kfree_skb(skb);
}
/**
* homa_cutoffs_pkt() - Handler for incoming CUTOFFS packets
* @skb: Incoming packet; size already verified large enough for header.
* This function now owns the packet.
* @hsk: Socket on which the packet was received.
*/
void homa_cutoffs_pkt(struct sk_buff *skb, struct homa_sock *hsk)
{
const struct in6_addr saddr = skb_canonical_ipv6_saddr(skb);
int i;
struct cutoffs_header *h = (struct cutoffs_header *) skb->data;
struct homa_peer *peer = homa_peer_find(hsk->homa->peers,
&saddr, &hsk->inet);
if (!IS_ERR(peer)) {
peer->unsched_cutoffs[0] = INT_MAX;
for (i = 1; i < HOMA_MAX_PRIORITIES; i++)
peer->unsched_cutoffs[i] = ntohl(h->unsched_cutoffs[i]);
peer->cutoff_version = h->cutoff_version;
}
kfree_skb(skb);
}
/**
* homa_need_ack_pkt() - Handler for incoming NEED_ACK packets
* @skb: Incoming packet; size already verified large enough for header.
* This function now owns the packet.
* @hsk: Socket on which the packet was received.
* @rpc: The RPC named in the packet header, or NULL if no such
* RPC exists. The RPC has been locked by the caller.
*/
void homa_need_ack_pkt(struct sk_buff *skb, struct homa_sock *hsk,
struct homa_rpc *rpc)
{
struct common_header *h = (struct common_header *) skb->data;
const struct in6_addr saddr = skb_canonical_ipv6_saddr(skb);
__u64 id = homa_local_id(h->sender_id);
struct ack_header ack;
struct homa_peer *peer;
tt_record1("Received NEED_ACK for id %d", id);
/* Return if it's not safe for the peer to purge its state
* for this RPC (the RPC still exists and we haven't received
* the entire response), or if we can't find peer info.
*/
if ((rpc != NULL) && ((rpc->state != RPC_INCOMING)
|| rpc->msgin.bytes_remaining)) {
tt_record3("NEED_ACK arrived for id %d before message received, state %d, remaining %d",
rpc->id, rpc->state, rpc->msgin.bytes_remaining);
homa_freeze(rpc, NEED_ACK_MISSING_DATA,
"Freezing because NEED_ACK received before message complete, id %d, peer 0x%x");
goto done;
} else {
peer = homa_peer_find(hsk->homa->peers, &saddr, &hsk->inet);
if (IS_ERR(peer))
goto done;
}
/* Send an ACK for this RPC. At the same time, include all of the
* other acks available for the peer. Note: can't use rpc below,
* since it may be NULL.
*/
ack.common.type = ACK;
ack.common.sport = h->dport;
ack.common.dport = h->sport;
ack.common.flags = HOMA_TCP_FLAGS;
ack.common.urgent = htons(HOMA_TCP_URGENT);
ack.common.sender_id = cpu_to_be64(id);
ack.num_acks = htons(homa_peer_get_acks(peer,
HOMA_MAX_ACKS_PER_PKT, ack.acks));
__homa_xmit_control(&ack, sizeof(ack), peer, hsk);
tt_record3("Responded to NEED_ACK for id %d, peer %0x%x with %d other acks",
id, tt_addr(saddr), ntohs(ack.num_acks));
done:
kfree_skb(skb);
}
/**
* homa_ack_pkt() - Handler for incoming ACK packets
* @skb: Incoming packet; size already verified large enough for header.
* This function now owns the packet.
* @hsk: Socket on which the packet was received.
* @rpc: The RPC named in the packet header, or NULL if no such
* RPC exists. The RPC has been locked by the caller but will
* be unlocked here.
*/
void homa_ack_pkt(struct sk_buff *skb, struct homa_sock *hsk,
struct homa_rpc *rpc)
{
struct ack_header *h = (struct ack_header *) skb->data;
const struct in6_addr saddr = skb_canonical_ipv6_saddr(skb);
int i, count;
if (rpc != NULL) {
tt_record1("homa_ack_pkt freeing rpc id %d", rpc->id);
homa_rpc_free(rpc);
homa_rpc_unlock(rpc);
}
count = ntohs(h->num_acks);
for (i = 0; i < count; i++)
homa_rpc_acked(hsk, &saddr, &h->acks[i]);
tt_record3("ACK received for id %d, peer 0x%x, with %d other acks",
homa_local_id(h->common.sender_id),
tt_addr(saddr), count);
kfree_skb(skb);
}
/**
* homa_choose_fifo_grant() - This function is invoked occasionally to give
* a high-priority grant to the oldest incoming message. We do this in
* order to reduce the starvation that SRPT can cause for long messages.
* Note: this method is obsolete and should never be invoked; it's code is
* being retained until fifo grants are reimplemented using the new grant
* mechanism.
* @homa: Overall data about the Homa protocol implementation. The
* grantable_lock must be held by the caller.
* Return: An RPC to which to send a FIFO grant, or NULL if there is
* no appropriate RPC. This method doesn't actually send a grant,
* but it updates @msgin.granted to reflect the desired grant.
* Also updates homa->total_incoming.
*/
struct homa_rpc *homa_choose_fifo_grant(struct homa *homa)
{
struct homa_rpc *rpc, *oldest;
__u64 oldest_birth;
int granted;
oldest = NULL;
oldest_birth = ~0;
/* Find the oldest message that doesn't currently have an
* outstanding "pity grant".
*/
list_for_each_entry(rpc, &homa->grantable_rpcs, grantable_links) {
int received, on_the_way;
if (rpc->msgin.birth >= oldest_birth)
continue;
received = (rpc->msgin.length
- rpc->msgin.bytes_remaining);
on_the_way = rpc->msgin.granted - received;
if (on_the_way > homa->unsched_bytes) {
/* The last "pity" grant hasn't been used
* up yet.
*/
continue;
}
oldest = rpc;
oldest_birth = rpc->msgin.birth;
}
if (oldest == NULL)
return NULL;
INC_METRIC(fifo_grants, 1);
if ((oldest->msgin.length - oldest->msgin.bytes_remaining)
== oldest->msgin.granted)
INC_METRIC(fifo_grants_no_incoming, 1);
oldest->silent_ticks = 0;
granted = homa->fifo_grant_increment;
oldest->msgin.granted += granted;
if (oldest->msgin.granted >= oldest->msgin.length) {
granted -= oldest->msgin.granted - oldest->msgin.length;
oldest->msgin.granted = oldest->msgin.length;
// homa_remove_grantable_locked(homa, oldest);
}
/* Try to update homa->total_incoming; if we can't lock
* the RPC, just skip it (waiting could deadlock), and it
* will eventually get updated elsewhere.
*/
if (homa_bucket_try_lock(oldest->bucket, oldest->id,
"homa_choose_fifo_grant")) {
homa_grant_update_incoming(oldest, homa);
homa_rpc_unlock(oldest);
}
if (oldest->msgin.granted < (oldest->msgin.length
- oldest->msgin.bytes_remaining)) {
/* We've already received all of the bytes in the new
* grant; most likely this means that the sender sent extra
* data after the last fifo grant (e.g. by rounding up to a
* TSO packet). Don't send this grant.
*/
return NULL;
}
return oldest;
}
/**
* homa_rpc_abort() - Terminate an RPC.
* @rpc: RPC to be terminated. Must be locked by caller.
* @error: A negative errno value indicating the error that caused the abort.
* If this is a client RPC, the error will be returned to the
* application; if it's a server RPC, the error is ignored and
* we just free the RPC.
*/
void homa_rpc_abort(struct homa_rpc *rpc, int error)
{
if (!homa_is_client(rpc->id)) {
INC_METRIC(server_rpc_discards, 1);
tt_record3("aborting server RPC: peer 0x%x, id %d, error %d",
tt_addr(rpc->peer->addr), rpc->id, error);
homa_rpc_free(rpc);
return;
}
tt_record3("aborting client RPC: peer 0x%x, id %d, error %d",
tt_addr(rpc->peer->addr), rpc->id, error);
rpc->error = error;
homa_sock_lock(rpc->hsk, "homa_rpc_abort");
if (!rpc->hsk->shutdown)
homa_rpc_handoff(rpc);
homa_sock_unlock(rpc->hsk);
}
/**
* homa_abort_rpcs() - Abort all RPCs to/from a particular peer.
* @homa: Overall data about the Homa protocol implementation.
* @addr: Address (network order) of the destination whose RPCs are
* to be aborted.
* @port: If nonzero, then RPCs will only be aborted if they were
* targeted at this server port.
* @error: Negative errno value indicating the reason for the abort.
*/
void homa_abort_rpcs(struct homa *homa, const struct in6_addr *addr,
int port, int error)
{
struct homa_socktab_scan scan;
struct homa_sock *hsk;
struct homa_rpc *rpc, *tmp;
rcu_read_lock();
for (hsk = homa_socktab_start_scan(homa->port_map, &scan);
hsk != NULL; hsk = homa_socktab_next(&scan)) {
/* Skip the (expensive) lock acquisition if there's no
* work to do.
*/
if (list_empty(&hsk->active_rpcs))
continue;
if (!homa_protect_rpcs(hsk))
continue;
list_for_each_entry_safe(rpc, tmp, &hsk->active_rpcs,
active_links) {