int dvb_ringbuffer_empty(struct dvb_ringbuffer *rbuf) { /* smp_load_acquire() to load write pointer on reader side * this pairs with smp_store_release() in dvb_ringbuffer_write(), * dvb_ringbuffer_write_user(), or dvb_ringbuffer_reset() * * for memory barriers also see Documentation/circular-buffers.txt */ return (rbuf->pread == smp_load_acquire(&rbuf->pwrite)); }
void iteration(int thread, int *count) { test_fn *f = test_fns[thread]; while (smp_load_acquire(&go) == *count) ; int r = f(); results[thread] = r; smp_store_release(&done[thread], true); (*count)++; }
/* * Fill out an ACK packet. */ static size_t rxrpc_fill_out_ack(struct rxrpc_call *call, struct rxrpc_ack_buffer *pkt, rxrpc_seq_t *_hard_ack, rxrpc_seq_t *_top, u8 reason) { rxrpc_serial_t serial; rxrpc_seq_t hard_ack, top, seq; int ix; u32 mtu, jmax; u8 *ackp = pkt->acks; /* Barrier against rxrpc_input_data(). */ serial = call->ackr_serial; hard_ack = READ_ONCE(call->rx_hard_ack); top = smp_load_acquire(&call->rx_top); *_hard_ack = hard_ack; *_top = top; pkt->ack.bufferSpace = htons(8); pkt->ack.maxSkew = htons(call->ackr_skew); pkt->ack.firstPacket = htonl(hard_ack + 1); pkt->ack.previousPacket = htonl(call->ackr_prev_seq); pkt->ack.serial = htonl(serial); pkt->ack.reason = reason; pkt->ack.nAcks = top - hard_ack; if (reason == RXRPC_ACK_PING) pkt->whdr.flags |= RXRPC_REQUEST_ACK; if (after(top, hard_ack)) { seq = hard_ack + 1; do { ix = seq & RXRPC_RXTX_BUFF_MASK; if (call->rxtx_buffer[ix]) *ackp++ = RXRPC_ACK_TYPE_ACK; else *ackp++ = RXRPC_ACK_TYPE_NACK; seq++; } while (before_eq(seq, top)); } mtu = call->conn->params.peer->if_mtu; mtu -= call->conn->params.peer->hdrsize; jmax = (call->nr_jumbo_bad > 3) ? 1 : rxrpc_rx_jumbo_max; pkt->ackinfo.rxMTU = htonl(rxrpc_rx_mtu); pkt->ackinfo.maxMTU = htonl(mtu); pkt->ackinfo.rwind = htonl(call->rx_winsize); pkt->ackinfo.jumbo_max = htonl(jmax); *ackp++ = 0; *ackp++ = 0; *ackp++ = 0; return top - hard_ack + 3; }
void dvb_ringbuffer_flush(struct dvb_ringbuffer *rbuf) { /* dvb_ringbuffer_flush() counts as read operation * smp_load_acquire() to load write pointer * smp_store_release() to update read pointer, this ensures that the * correct pointer is visible for subsequent dvb_ringbuffer_free() * calls on other cpu cores */ smp_store_release(&rbuf->pread, smp_load_acquire(&rbuf->pwrite)); rbuf->error = 0; }
/* * Begin iteration through a server list, starting with the last used server if * possible, or the last recorded good server if not. */ static bool afs_start_vl_iteration(struct afs_vl_cursor *vc) { struct afs_cell *cell = vc->cell; unsigned int dns_lookup_count; if (cell->dns_source == DNS_RECORD_UNAVAILABLE || cell->dns_expiry <= ktime_get_real_seconds()) { dns_lookup_count = smp_load_acquire(&cell->dns_lookup_count); set_bit(AFS_CELL_FL_DO_LOOKUP, &cell->flags); queue_work(afs_wq, &cell->manager); if (cell->dns_source == DNS_RECORD_UNAVAILABLE) { if (wait_var_event_interruptible( &cell->dns_lookup_count, smp_load_acquire(&cell->dns_lookup_count) != dns_lookup_count) < 0) { vc->error = -ERESTARTSYS; return false; } } /* Status load is ordered after lookup counter load */ if (cell->dns_source == DNS_RECORD_UNAVAILABLE) { vc->error = -EDESTADDRREQ; return false; } } read_lock(&cell->vl_servers_lock); vc->server_list = afs_get_vlserverlist( rcu_dereference_protected(cell->vl_servers, lockdep_is_held(&cell->vl_servers_lock))); read_unlock(&cell->vl_servers_lock); if (!vc->server_list->nr_servers) return false; vc->untried = (1UL << vc->server_list->nr_servers) - 1; vc->index = -1; return true; }
ssize_t dvb_ringbuffer_avail(struct dvb_ringbuffer *rbuf) { ssize_t avail; /* smp_load_acquire() to load write pointer on reader side * this pairs with smp_store_release() in dvb_ringbuffer_write(), * dvb_ringbuffer_write_user(), or dvb_ringbuffer_reset() */ avail = smp_load_acquire(&rbuf->pwrite) - rbuf->pread; if (avail < 0) avail += rbuf->size; return avail; }
/* * Discard a packet we've used up and advance the Rx window by one. */ static void rxrpc_rotate_rx_window(struct rxrpc_call *call) { struct rxrpc_skb_priv *sp; struct sk_buff *skb; rxrpc_serial_t serial; rxrpc_seq_t hard_ack, top; u8 flags; int ix; _enter("%d", call->debug_id); hard_ack = call->rx_hard_ack; top = smp_load_acquire(&call->rx_top); ASSERT(before(hard_ack, top)); hard_ack++; ix = hard_ack & RXRPC_RXTX_BUFF_MASK; skb = call->rxtx_buffer[ix]; rxrpc_see_skb(skb, rxrpc_skb_rx_rotated); sp = rxrpc_skb(skb); flags = sp->hdr.flags; serial = sp->hdr.serial; if (call->rxtx_annotations[ix] & RXRPC_RX_ANNO_JUMBO) serial += (call->rxtx_annotations[ix] & RXRPC_RX_ANNO_JUMBO) - 1; call->rxtx_buffer[ix] = NULL; call->rxtx_annotations[ix] = 0; /* Barrier against rxrpc_input_data(). */ smp_store_release(&call->rx_hard_ack, hard_ack); rxrpc_free_skb(skb, rxrpc_skb_rx_freed); _debug("%u,%u,%02x", hard_ack, top, flags); trace_rxrpc_receive(call, rxrpc_receive_rotate, serial, hard_ack); if (flags & RXRPC_LAST_PACKET) { rxrpc_end_rx_phase(call, serial); } else { /* Check to see if there's an ACK that needs sending. */ if (after_eq(hard_ack, call->ackr_consumed + 2) || after_eq(top, call->ackr_seen + 2) || (hard_ack == top && after(hard_ack, call->ackr_consumed))) rxrpc_propose_ACK(call, RXRPC_ACK_DELAY, 0, serial, true, false, rxrpc_propose_ack_rotate_rx); if (call->ackr_reason) rxrpc_send_call_packet(call, RXRPC_PACKET_TYPE_ACK); } }
void run_test(int threads, int n) { reset(); // Let my people go smp_store_release(&go, n+1); // Wait for everyone for (int i = 0; i < threads; i++) { while (!smp_load_acquire(&done[i])) ; smp_store_release(&done[i], false); } // Everyone done, process results. process_results(results); }
static int fq_enqueue(struct sk_buff *skb, struct Qdisc *sch, struct sk_buff **to_free) { struct fq_sched_data *q = qdisc_priv(sch); struct fq_flow *f; if (unlikely(sch->q.qlen >= sch->limit)) return qdisc_drop(skb, sch, to_free); f = fq_classify(skb, q); if (unlikely(f->qlen >= q->flow_plimit && f != &q->internal)) { q->stat_flows_plimit++; return qdisc_drop(skb, sch, to_free); } f->qlen++; if (skb_is_retransmit(skb)) q->stat_tcp_retrans++; qdisc_qstats_backlog_inc(sch, skb); if (fq_flow_is_detached(f)) { struct sock *sk = skb->sk; fq_flow_add_tail(&q->new_flows, f); if (time_after(jiffies, f->age + q->flow_refill_delay)) f->credit = max_t(u32, f->credit, q->quantum); if (sk && q->rate_enable) { if (unlikely(smp_load_acquire(&sk->sk_pacing_status) != SK_PACING_FQ)) smp_store_release(&sk->sk_pacing_status, SK_PACING_FQ); } q->inactive_flows--; } /* Note: this overwrites f->age */ flow_queue_add(f, skb); if (unlikely(f == &q->internal)) { q->stat_internal_packets++; } sch->q.qlen++; return NET_XMIT_SUCCESS; }
void quarantine_reduce(void) { size_t new_quarantine_size; unsigned long flags; struct qlist to_free = QLIST_INIT; size_t size_to_free = 0; void **last; /* smp_load_acquire() here pairs with smp_store_release() below. */ if (likely(ACCESS_ONCE(global_quarantine.bytes) <= smp_load_acquire(&quarantine_size))) return; spin_lock_irqsave(&quarantine_lock, flags); /* Update quarantine size in case of hotplug. Allocate a fraction of * the installed memory to quarantine minus per-cpu queue limits. */ new_quarantine_size = (ACCESS_ONCE(totalram_pages) << PAGE_SHIFT) / QUARANTINE_FRACTION; new_quarantine_size -= QUARANTINE_PERCPU_SIZE * num_online_cpus(); /* Pairs with smp_load_acquire() above and in QUARANTINE_LOW_SIZE. */ smp_store_release(&quarantine_size, new_quarantine_size); last = global_quarantine.head; while (last) { struct kmem_cache *cache = qlink_to_cache(last); size_to_free += cache->size; if (!*last || size_to_free > global_quarantine.bytes - QUARANTINE_LOW_SIZE) break; last = (void **) *last; } qlist_move(&global_quarantine, last, &to_free, size_to_free); spin_unlock_irqrestore(&quarantine_lock, flags); qlist_free_all(&to_free, NULL); }
bool osq_lock(struct optimistic_spin_queue *lock) { struct optimistic_spin_node *node = this_cpu_ptr(&osq_node); struct optimistic_spin_node *prev, *next; int curr = encode_cpu(smp_processor_id()); int old; node->locked = 0; node->next = NULL; node->cpu = curr; /* * We need both ACQUIRE (pairs with corresponding RELEASE in * unlock() uncontended, or fastpath) and RELEASE (to publish * the node fields we just initialised) semantics when updating * the lock tail. */ old = atomic_xchg(&lock->tail, curr); if (old == OSQ_UNLOCKED_VAL) return true; prev = decode_cpu(old); node->prev = prev; WRITE_ONCE(prev->next, node); /* * Normally @prev is untouchable after the above store; because at that * moment unlock can proceed and wipe the node element from stack. * * However, since our nodes are static per-cpu storage, we're * guaranteed their existence -- this allows us to apply * cmpxchg in an attempt to undo our queueing. */ while (!READ_ONCE(node->locked)) { /* * If we need to reschedule bail... so we can block. */ if (need_resched()) goto unqueue; cpu_relax_lowlatency(); } return true; unqueue: /* * Step - A -- stabilize @prev * * Undo our @prev->next assignment; this will make @prev's * unlock()/unqueue() wait for a next pointer since @lock points to us * (or later). */ for (;;) { if (prev->next == node && cmpxchg(&prev->next, node, NULL) == node) break; /* * We can only fail the cmpxchg() racing against an unlock(), * in which case we should observe @node->locked becomming * true. */ if (smp_load_acquire(&node->locked)) return true; cpu_relax_lowlatency(); /* * Or we race against a concurrent unqueue()'s step-B, in which * case its step-C will write us a new @node->prev pointer. */ prev = READ_ONCE(node->prev); } /* * Step - B -- stabilize @next * * Similar to unlock(), wait for @node->next or move @lock from @node * back to @prev. */ next = osq_wait_next(lock, node, prev); if (!next) return false; /* * Step - C -- unlink * * @prev is stable because its still waiting for a new @prev->next * pointer, @next is stable because our @node->next pointer is NULL and * it will wait in Step-A. */ WRITE_ONCE(next->prev, prev); WRITE_ONCE(prev->next, next); return false; }
/** * dump_common_audit_data - helper to dump common audit data * @a : common audit data * */ static void dump_common_audit_data(struct audit_buffer *ab, struct common_audit_data *a) { char comm[sizeof(current->comm)]; /* * To keep stack sizes in check force programers to notice if they * start making this union too large! See struct lsm_network_audit * as an example of how to deal with large data. */ BUILD_BUG_ON(sizeof(a->u) > sizeof(void *)*2); audit_log_format(ab, " pid=%d comm=", task_tgid_nr(current)); audit_log_untrustedstring(ab, memcpy(comm, current->comm, sizeof(comm))); switch (a->type) { case LSM_AUDIT_DATA_NONE: return; case LSM_AUDIT_DATA_IPC: audit_log_format(ab, " key=%d ", a->u.ipc_id); break; case LSM_AUDIT_DATA_CAP: audit_log_format(ab, " capability=%d ", a->u.cap); break; case LSM_AUDIT_DATA_PATH: { struct inode *inode; audit_log_d_path(ab, " path=", &a->u.path); inode = d_backing_inode(a->u.path.dentry); if (inode) { audit_log_format(ab, " dev="); audit_log_untrustedstring(ab, inode->i_sb->s_id); audit_log_format(ab, " ino=%lu", inode->i_ino); } break; } case LSM_AUDIT_DATA_FILE: { struct inode *inode; audit_log_d_path(ab, " path=", &a->u.file->f_path); inode = file_inode(a->u.file); if (inode) { audit_log_format(ab, " dev="); audit_log_untrustedstring(ab, inode->i_sb->s_id); audit_log_format(ab, " ino=%lu", inode->i_ino); } break; } case LSM_AUDIT_DATA_IOCTL_OP: { struct inode *inode; audit_log_d_path(ab, " path=", &a->u.op->path); inode = a->u.op->path.dentry->d_inode; if (inode) { audit_log_format(ab, " dev="); audit_log_untrustedstring(ab, inode->i_sb->s_id); audit_log_format(ab, " ino=%lu", inode->i_ino); } audit_log_format(ab, " ioctlcmd=0x%hx", a->u.op->cmd); break; } case LSM_AUDIT_DATA_DENTRY: { struct inode *inode; audit_log_format(ab, " name="); audit_log_untrustedstring(ab, a->u.dentry->d_name.name); inode = d_backing_inode(a->u.dentry); if (inode) { audit_log_format(ab, " dev="); audit_log_untrustedstring(ab, inode->i_sb->s_id); audit_log_format(ab, " ino=%lu", inode->i_ino); } break; } case LSM_AUDIT_DATA_INODE: { struct dentry *dentry; struct inode *inode; inode = a->u.inode; dentry = d_find_alias(inode); if (dentry) { audit_log_format(ab, " name="); audit_log_untrustedstring(ab, dentry->d_name.name); dput(dentry); } audit_log_format(ab, " dev="); audit_log_untrustedstring(ab, inode->i_sb->s_id); audit_log_format(ab, " ino=%lu", inode->i_ino); break; } case LSM_AUDIT_DATA_TASK: { struct task_struct *tsk = a->u.tsk; if (tsk) { pid_t pid = task_tgid_nr(tsk); if (pid) { char comm[sizeof(tsk->comm)]; audit_log_format(ab, " opid=%d ocomm=", pid); audit_log_untrustedstring(ab, memcpy(comm, tsk->comm, sizeof(comm))); } } break; } case LSM_AUDIT_DATA_NET: if (a->u.net->sk) { struct sock *sk = a->u.net->sk; struct unix_sock *u; struct unix_address *addr; int len = 0; char *p = NULL; switch (sk->sk_family) { case AF_INET: { struct inet_sock *inet = inet_sk(sk); print_ipv4_addr(ab, inet->inet_rcv_saddr, inet->inet_sport, "laddr", "lport"); print_ipv4_addr(ab, inet->inet_daddr, inet->inet_dport, "faddr", "fport"); break; } #if IS_ENABLED(CONFIG_IPV6) case AF_INET6: { struct inet_sock *inet = inet_sk(sk); print_ipv6_addr(ab, &sk->sk_v6_rcv_saddr, inet->inet_sport, "laddr", "lport"); print_ipv6_addr(ab, &sk->sk_v6_daddr, inet->inet_dport, "faddr", "fport"); break; } #endif case AF_UNIX: u = unix_sk(sk); addr = smp_load_acquire(&u->addr); if (!addr) break; if (u->path.dentry) { audit_log_d_path(ab, " path=", &u->path); break; } len = addr->len-sizeof(short); p = &addr->name->sun_path[0]; audit_log_format(ab, " path="); if (*p) audit_log_untrustedstring(ab, p); else audit_log_n_hex(ab, p, len); break; } } switch (a->u.net->family) { case AF_INET: print_ipv4_addr(ab, a->u.net->v4info.saddr, a->u.net->sport, "saddr", "src"); print_ipv4_addr(ab, a->u.net->v4info.daddr, a->u.net->dport, "daddr", "dest"); break; case AF_INET6: print_ipv6_addr(ab, &a->u.net->v6info.saddr, a->u.net->sport, "saddr", "src"); print_ipv6_addr(ab, &a->u.net->v6info.daddr, a->u.net->dport, "daddr", "dest"); break; } if (a->u.net->netif > 0) { struct net_device *dev; /* NOTE: we always use init's namespace */ dev = dev_get_by_index(&init_net, a->u.net->netif); if (dev) { audit_log_format(ab, " netif=%s", dev->name); dev_put(dev); } } break; #ifdef CONFIG_KEYS case LSM_AUDIT_DATA_KEY: audit_log_format(ab, " key_serial=%u", a->u.key_struct.key); if (a->u.key_struct.key_desc) { audit_log_format(ab, " key_desc="); audit_log_untrustedstring(ab, a->u.key_struct.key_desc); } break; #endif case LSM_AUDIT_DATA_KMOD: audit_log_format(ab, " kmod="); audit_log_untrustedstring(ab, a->u.kmod_name); break; case LSM_AUDIT_DATA_IBPKEY: { struct in6_addr sbn_pfx; memset(&sbn_pfx.s6_addr, 0, sizeof(sbn_pfx.s6_addr)); memcpy(&sbn_pfx.s6_addr, &a->u.ibpkey->subnet_prefix, sizeof(a->u.ibpkey->subnet_prefix)); audit_log_format(ab, " pkey=0x%x subnet_prefix=%pI6c", a->u.ibpkey->pkey, &sbn_pfx); break; } case LSM_AUDIT_DATA_IBENDPORT: audit_log_format(ab, " device=%s port_num=%u", a->u.ibendport->dev_name, a->u.ibendport->port); break; } /* switch (a->type) */ }
/* * afs_lookup_cell - Look up or create a cell record. * @net: The network namespace * @name: The name of the cell. * @namesz: The strlen of the cell name. * @vllist: A colon/comma separated list of numeric IP addresses or NULL. * @excl: T if an error should be given if the cell name already exists. * * Look up a cell record by name and query the DNS for VL server addresses if * needed. Note that that actual DNS query is punted off to the manager thread * so that this function can return immediately if interrupted whilst allowing * cell records to be shared even if not yet fully constructed. */ struct afs_cell *afs_lookup_cell(struct afs_net *net, const char *name, unsigned int namesz, const char *vllist, bool excl) { struct afs_cell *cell, *candidate, *cursor; struct rb_node *parent, **pp; enum afs_cell_state state; int ret, n; _enter("%s,%s", name, vllist); if (!excl) { rcu_read_lock(); cell = afs_lookup_cell_rcu(net, name, namesz); rcu_read_unlock(); if (!IS_ERR(cell)) goto wait_for_cell; } /* Assume we're probably going to create a cell and preallocate and * mostly set up a candidate record. We can then use this to stash the * name, the net namespace and VL server addresses. * * We also want to do this before we hold any locks as it may involve * upcalling to userspace to make DNS queries. */ candidate = afs_alloc_cell(net, name, namesz, vllist); if (IS_ERR(candidate)) { _leave(" = %ld", PTR_ERR(candidate)); return candidate; } /* Find the insertion point and check to see if someone else added a * cell whilst we were allocating. */ write_seqlock(&net->cells_lock); pp = &net->cells.rb_node; parent = NULL; while (*pp) { parent = *pp; cursor = rb_entry(parent, struct afs_cell, net_node); n = strncasecmp(cursor->name, name, min_t(size_t, cursor->name_len, namesz)); if (n == 0) n = cursor->name_len - namesz; if (n < 0) pp = &(*pp)->rb_left; else if (n > 0) pp = &(*pp)->rb_right; else goto cell_already_exists; } cell = candidate; candidate = NULL; rb_link_node_rcu(&cell->net_node, parent, pp); rb_insert_color(&cell->net_node, &net->cells); atomic_inc(&net->cells_outstanding); write_sequnlock(&net->cells_lock); queue_work(afs_wq, &cell->manager); wait_for_cell: _debug("wait_for_cell"); wait_var_event(&cell->state, ({ state = smp_load_acquire(&cell->state); /* vs error */ state == AFS_CELL_ACTIVE || state == AFS_CELL_FAILED; }));
/* * Deliver messages to a call. This keeps processing packets until the buffer * is filled and we find either more DATA (returns 0) or the end of the DATA * (returns 1). If more packets are required, it returns -EAGAIN. */ static int rxrpc_recvmsg_data(struct socket *sock, struct rxrpc_call *call, struct msghdr *msg, struct iov_iter *iter, size_t len, int flags, size_t *_offset) { struct rxrpc_skb_priv *sp; struct sk_buff *skb; rxrpc_seq_t hard_ack, top, seq; size_t remain; bool last; unsigned int rx_pkt_offset, rx_pkt_len; int ix, copy, ret = -EAGAIN, ret2; rx_pkt_offset = call->rx_pkt_offset; rx_pkt_len = call->rx_pkt_len; if (call->state >= RXRPC_CALL_SERVER_ACK_REQUEST) { seq = call->rx_hard_ack; ret = 1; goto done; } /* Barriers against rxrpc_input_data(). */ hard_ack = call->rx_hard_ack; top = smp_load_acquire(&call->rx_top); for (seq = hard_ack + 1; before_eq(seq, top); seq++) { ix = seq & RXRPC_RXTX_BUFF_MASK; skb = call->rxtx_buffer[ix]; if (!skb) { trace_rxrpc_recvmsg(call, rxrpc_recvmsg_hole, seq, rx_pkt_offset, rx_pkt_len, 0); break; } smp_rmb(); rxrpc_see_skb(skb, rxrpc_skb_rx_seen); sp = rxrpc_skb(skb); if (!(flags & MSG_PEEK)) trace_rxrpc_receive(call, rxrpc_receive_front, sp->hdr.serial, seq); if (msg) sock_recv_timestamp(msg, sock->sk, skb); if (rx_pkt_offset == 0) { ret2 = rxrpc_locate_data(call, skb, &call->rxtx_annotations[ix], &rx_pkt_offset, &rx_pkt_len); trace_rxrpc_recvmsg(call, rxrpc_recvmsg_next, seq, rx_pkt_offset, rx_pkt_len, ret2); if (ret2 < 0) { ret = ret2; goto out; } } else { trace_rxrpc_recvmsg(call, rxrpc_recvmsg_cont, seq, rx_pkt_offset, rx_pkt_len, 0); } /* We have to handle short, empty and used-up DATA packets. */ remain = len - *_offset; copy = rx_pkt_len; if (copy > remain) copy = remain; if (copy > 0) { ret2 = skb_copy_datagram_iter(skb, rx_pkt_offset, iter, copy); if (ret2 < 0) { ret = ret2; goto out; } /* handle piecemeal consumption of data packets */ rx_pkt_offset += copy; rx_pkt_len -= copy; *_offset += copy; } if (rx_pkt_len > 0) { trace_rxrpc_recvmsg(call, rxrpc_recvmsg_full, seq, rx_pkt_offset, rx_pkt_len, 0); ASSERTCMP(*_offset, ==, len); ret = 0; break; } /* The whole packet has been transferred. */ last = sp->hdr.flags & RXRPC_LAST_PACKET; if (!(flags & MSG_PEEK)) rxrpc_rotate_rx_window(call); rx_pkt_offset = 0; rx_pkt_len = 0; if (last) { ASSERTCMP(seq, ==, READ_ONCE(call->rx_top)); ret = 1; goto out; } }
/* * Allocate a new incoming call from the prealloc pool, along with a connection * and a peer as necessary. */ static struct rxrpc_call *rxrpc_alloc_incoming_call(struct rxrpc_sock *rx, struct rxrpc_local *local, struct rxrpc_connection *conn, struct sk_buff *skb) { struct rxrpc_backlog *b = rx->backlog; struct rxrpc_peer *peer, *xpeer; struct rxrpc_call *call; unsigned short call_head, conn_head, peer_head; unsigned short call_tail, conn_tail, peer_tail; unsigned short call_count, conn_count; /* #calls >= #conns >= #peers must hold true. */ call_head = smp_load_acquire(&b->call_backlog_head); call_tail = b->call_backlog_tail; call_count = CIRC_CNT(call_head, call_tail, RXRPC_BACKLOG_MAX); conn_head = smp_load_acquire(&b->conn_backlog_head); conn_tail = b->conn_backlog_tail; conn_count = CIRC_CNT(conn_head, conn_tail, RXRPC_BACKLOG_MAX); ASSERTCMP(conn_count, >=, call_count); peer_head = smp_load_acquire(&b->peer_backlog_head); peer_tail = b->peer_backlog_tail; ASSERTCMP(CIRC_CNT(peer_head, peer_tail, RXRPC_BACKLOG_MAX), >=, conn_count); if (call_count == 0) return NULL; if (!conn) { /* No connection. We're going to need a peer to start off * with. If one doesn't yet exist, use a spare from the * preallocation set. We dump the address into the spare in * anticipation - and to save on stack space. */ xpeer = b->peer_backlog[peer_tail]; if (rxrpc_extract_addr_from_skb(&xpeer->srx, skb) < 0) return NULL; peer = rxrpc_lookup_incoming_peer(local, xpeer); if (peer == xpeer) { b->peer_backlog[peer_tail] = NULL; smp_store_release(&b->peer_backlog_tail, (peer_tail + 1) & (RXRPC_BACKLOG_MAX - 1)); } /* Now allocate and set up the connection */ conn = b->conn_backlog[conn_tail]; b->conn_backlog[conn_tail] = NULL; smp_store_release(&b->conn_backlog_tail, (conn_tail + 1) & (RXRPC_BACKLOG_MAX - 1)); rxrpc_get_local(local); conn->params.local = local; conn->params.peer = peer; rxrpc_see_connection(conn); rxrpc_new_incoming_connection(rx, conn, skb); } else { rxrpc_get_connection(conn); } /* And now we can allocate and set up a new call */ call = b->call_backlog[call_tail]; b->call_backlog[call_tail] = NULL; smp_store_release(&b->call_backlog_tail, (call_tail + 1) & (RXRPC_BACKLOG_MAX - 1)); rxrpc_see_call(call); call->conn = conn; call->peer = rxrpc_get_peer(conn->params.peer); call->cong_cwnd = call->peer->cong_cwnd; return call; }