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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>
95 lines
2.3 KiB
C
95 lines
2.3 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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* Definitions for the global table of packet flows.
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*/
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#ifndef FLOW_TABLE_H
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#define FLOW_TABLE_H
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#include "tcp_conn.h"
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/**
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* union flow - Descriptor for a logical packet flow (e.g. connection)
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* @f: Fields common between all variants
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* @tcp: Fields for non-spliced TCP connections
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* @tcp_splice: Fields for spliced TCP connections
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*/
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union flow {
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struct flow_common f;
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struct tcp_tap_conn tcp;
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struct tcp_splice_conn tcp_splice;
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};
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/* Global Flow Table */
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extern unsigned flow_count;
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extern union flow flowtab[];
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/** flow_idx - Index of flow from common structure
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* @f: Common flow fields pointer
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*
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* Return: index of @f in the flow table
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*/
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static inline unsigned flow_idx(const struct flow_common *f)
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{
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return (union flow *)f - flowtab;
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}
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/** FLOW_IDX - Find the index of a flow
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* @f_: Flow pointer, either union flow * or protocol specific
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*
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* Return: index of @f in the flow table
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*/
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#define FLOW_IDX(f_) (flow_idx(&(f_)->f))
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/** FLOW - Flow entry at a given index
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* @idx: Flow index
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*
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* Return: pointer to entry @idx in the flow table
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*/
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#define FLOW(idx) (&flowtab[(idx)])
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/** flow_at_sidx - Flow entry for a given sidx
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* @sidx: Flow & side index
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*
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* Return: pointer to the corresponding flow entry, or NULL
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*/
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static inline union flow *flow_at_sidx(flow_sidx_t sidx)
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{
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if (sidx.flow >= FLOW_MAX)
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return NULL;
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return FLOW(sidx.flow);
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}
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/** flow_sidx_t - Index of one side of a flow from common structure
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* @f: Common flow fields pointer
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* @side: Which side to refer to (0 or 1)
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*
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* Return: index of @f and @side in the flow table
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*/
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static inline flow_sidx_t flow_sidx(const struct flow_common *f,
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int side)
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{
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/* cppcheck-suppress [knownConditionTrueFalse, unmatchedSuppression] */
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ASSERT(side == !!side);
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return (flow_sidx_t){
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.side = side,
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.flow = flow_idx(f),
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};
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}
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/** FLOW_SIDX - Find the index of one side of a flow
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* @f_: Flow pointer, either union flow * or protocol specific
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* @side: Which side to index (0 or 1)
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*
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* Return: index of @f and @side in the flow table
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*/
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#define FLOW_SIDX(f_, side) (flow_sidx(&(f_)->f, (side)))
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union flow *flow_alloc(void);
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void flow_alloc_cancel(union flow *flow);
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#endif /* FLOW_TABLE_H */
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