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Currently tcp.c open codes the process of allocating a new flow from the flow table: twice, in fact, once for guest to host and once for host to guest connections. This duplication isn't ideal and will get worse as we add more protocols to the flow table. It also makes it harder to experiment with different ways of handling flow table allocation. Instead, introduce a function to allocate a new flow: flow_alloc(). In some cases we currently check if we're able to allocate, but delay the actual allocation. We now handle that slightly differently with a flow_alloc_cancel() function to back out a recent allocation. We have that separate from a flow_free() function, because future changes we have in mind will need to handle this case a little differently. Signed-off-by: David Gibson <david@gibson.dropbear.id.au> Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
149 lines
3.3 KiB
C
149 lines
3.3 KiB
C
/* SPDX-License-Identifier: GPL-2.0-or-later
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* Copyright Red Hat
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* Author: David Gibson <david@gibson.dropbear.id.au>
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*
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* Tracking for logical "flows" of packets.
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*/
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#include <stdint.h>
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#include <stdio.h>
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#include <unistd.h>
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#include <string.h>
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#include "util.h"
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#include "passt.h"
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#include "siphash.h"
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#include "inany.h"
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#include "flow.h"
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#include "flow_table.h"
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const char *flow_type_str[] = {
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[FLOW_TYPE_NONE] = "<none>",
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[FLOW_TCP] = "TCP connection",
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[FLOW_TCP_SPLICE] = "TCP connection (spliced)",
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};
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static_assert(ARRAY_SIZE(flow_type_str) == FLOW_NUM_TYPES,
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"flow_type_str[] doesn't match enum flow_type");
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/* Global Flow Table */
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unsigned flow_count;
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union flow flowtab[FLOW_MAX];
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/* Last time the flow timers ran */
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static struct timespec flow_timer_run;
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/** flow_log_ - Log flow-related message
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* @f: flow the message is related to
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* @pri: Log priority
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* @fmt: Format string
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* @...: printf-arguments
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*/
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void flow_log_(const struct flow_common *f, int pri, const char *fmt, ...)
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{
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char msg[BUFSIZ];
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va_list args;
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va_start(args, fmt);
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(void)vsnprintf(msg, sizeof(msg), fmt, args);
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va_end(args);
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logmsg(pri, "Flow %u (%s): %s", flow_idx(f), FLOW_TYPE(f), msg);
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}
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/**
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* flow_alloc() - Allocate a new flow
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*
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* Return: pointer to an unused flow entry, or NULL if the table is full
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*/
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union flow *flow_alloc(void)
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{
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if (flow_count >= FLOW_MAX)
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return NULL;
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return &flowtab[flow_count++];
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}
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/**
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* flow_alloc_cancel() - Free a newly allocated flow
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* @flow: Flow to deallocate
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*
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* @flow must be the last flow allocated by flow_alloc()
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*/
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void flow_alloc_cancel(union flow *flow)
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{
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ASSERT(FLOW_IDX(flow) == flow_count - 1);
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memset(flow, 0, sizeof(*flow));
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flow_count--;
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}
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/**
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* flow_table_compact() - Perform compaction on flow table
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* @c: Execution context
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* @hole: Pointer to recently closed flow
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*/
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void flow_table_compact(const struct ctx *c, union flow *hole)
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{
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union flow *from;
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if (FLOW_IDX(hole) == --flow_count) {
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debug("flow: table compaction: maximum index was %u (%p)",
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FLOW_IDX(hole), (void *)hole);
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memset(hole, 0, sizeof(*hole));
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return;
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}
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from = flowtab + flow_count;
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memcpy(hole, from, sizeof(*hole));
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switch (from->f.type) {
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case FLOW_TCP:
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tcp_tap_conn_update(c, &from->tcp, &hole->tcp);
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break;
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case FLOW_TCP_SPLICE:
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tcp_splice_conn_update(c, &hole->tcp_splice);
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break;
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default:
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die("Unexpected %s in tcp_table_compact()",
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FLOW_TYPE(&from->f));
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}
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debug("flow: table compaction (%s): old index %u, new index %u, "
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"from: %p, to: %p",
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FLOW_TYPE(&from->f), FLOW_IDX(from), FLOW_IDX(hole),
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(void *)from, (void *)hole);
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memset(from, 0, sizeof(*from));
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}
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/**
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* flow_defer_handler() - Handler for per-flow deferred and timed tasks
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* @c: Execution context
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* @now: Current timestamp
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*/
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void flow_defer_handler(const struct ctx *c, const struct timespec *now)
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{
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bool timer = false;
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union flow *flow;
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if (timespec_diff_ms(now, &flow_timer_run) >= FLOW_TIMER_INTERVAL) {
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timer = true;
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flow_timer_run = *now;
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}
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for (flow = flowtab + flow_count - 1; flow >= flowtab; flow--) {
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switch (flow->f.type) {
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case FLOW_TCP:
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tcp_flow_defer(c, flow);
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break;
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case FLOW_TCP_SPLICE:
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tcp_splice_flow_defer(c, flow);
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if (timer)
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tcp_splice_timer(c, flow);
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break;
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default:
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/* Assume other flow types don't need any handling */
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;
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}
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}
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}
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