pf: Do not hold PF_RULES_RLOCK while processing Ethernet rules
Avoid the overhead of acquiring a (read) RULES lock when processing the Ethernet rules. We can get away with that because when rules are modified they're staged in V_pf_keth_inactive. We take care to ensure the swap to V_pf_keth is atomic, so that pf_test_eth_rule() always sees either the old rules, or the new ruleset. We need to take care not to delete the old ruleset until we're sure no pf_test_eth_rule() is still running with those. We accomplish that by using NET_EPOCH_CALL() to actually free the old rules. Sponsored by: Rubicon Communications, LLC ("Netgate") Differential Revision: https://reviews.freebsd.org/D31739
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@ -39,6 +39,7 @@
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#include <sys/queue.h>
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#include <sys/counter.h>
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#include <sys/cpuset.h>
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#include <sys/epoch.h>
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#include <sys/malloc.h>
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#include <sys/nv.h>
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#include <sys/refcount.h>
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@ -624,6 +625,8 @@ struct pf_keth_settings {
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struct pf_keth_rules rules;
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uint32_t ticket;
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int open;
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struct vnet *vnet;
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struct epoch_context epoch_ctx;
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};
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union pf_krule_ptr {
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@ -3712,18 +3712,18 @@ pf_test_eth_rule(int dir, struct pfi_kkif *kif, struct mbuf *m)
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struct ether_header *e;
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struct pf_keth_rule *r, *rm;
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struct pf_mtag *mtag;
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struct pf_keth_settings *settings;
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uint8_t action;
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PF_RULES_RLOCK_TRACKER;
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NET_EPOCH_ASSERT();
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MPASS(kif->pfik_ifp->if_vnet == curvnet);
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NET_EPOCH_ASSERT();
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e = mtod(m, struct ether_header *);
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PF_RULES_RLOCK();
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r = TAILQ_FIRST(&V_pf_keth->rules);
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settings = ck_pr_load_ptr(&V_pf_keth);
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r = TAILQ_FIRST(&settings->rules);
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rm = NULL;
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while (r != NULL) {
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@ -3753,26 +3753,21 @@ pf_test_eth_rule(int dir, struct pfi_kkif *kif, struct mbuf *m)
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r = rm;
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/* Default to pass. */
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if (r == NULL) {
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PF_RULES_RUNLOCK();
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if (r == NULL)
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return (PF_PASS);
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}
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/* Execute action. */
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counter_u64_add(r->packets[dir == PF_OUT], 1);
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counter_u64_add(r->bytes[dir == PF_OUT], m_length(m, NULL));
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/* Shortcut. Don't tag if we're just going to drop anyway. */
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if (r->action == PF_DROP) {
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PF_RULES_RUNLOCK();
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if (r->action == PF_DROP)
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return (PF_DROP);
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}
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if (r->tag > 0) {
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mtag = pf_get_mtag(m);
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if (mtag == NULL) {
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counter_u64_add(V_pf_status.counters[PFRES_MEMORY], 1);
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PF_RULES_RUNLOCK();
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return (PF_DROP);
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}
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mtag->tag = r->tag;
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@ -3782,7 +3777,6 @@ pf_test_eth_rule(int dir, struct pfi_kkif *kif, struct mbuf *m)
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mtag = pf_get_mtag(m);
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if (mtag == NULL) {
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counter_u64_add(V_pf_status.counters[PFRES_MEMORY], 1);
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PF_RULES_RUNLOCK();
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return (PF_DROP);
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}
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mtag->qid = r->qid;
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@ -3790,8 +3784,6 @@ pf_test_eth_rule(int dir, struct pfi_kkif *kif, struct mbuf *m)
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action = r->action;
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PF_RULES_RUNLOCK();
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return (action);
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}
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@ -107,6 +107,7 @@ static void pf_empty_kpool(struct pf_kpalist *);
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static int pfioctl(struct cdev *, u_long, caddr_t, int,
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struct thread *);
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static int pf_begin_eth(uint32_t *);
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static void pf_rollback_eth_cb(struct epoch_context *);
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static int pf_rollback_eth(uint32_t);
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static int pf_commit_eth(uint32_t);
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static void pf_free_eth_rule(struct pf_keth_rule *);
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@ -701,6 +702,12 @@ pf_begin_eth(uint32_t *ticket)
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PF_RULES_WASSERT();
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if (V_pf_keth_inactive->open) {
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/* We may be waiting for NET_EPOCH_CALL(pf_rollback_eth_cb) to
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* finish. */
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return (EBUSY);
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}
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/* Purge old inactive rules. */
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TAILQ_FOREACH_SAFE(rule, &V_pf_keth_inactive->rules, entries, tmp) {
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TAILQ_REMOVE(&V_pf_keth_inactive->rules, rule, entries);
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@ -713,6 +720,24 @@ pf_begin_eth(uint32_t *ticket)
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return (0);
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}
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static void
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pf_rollback_eth_cb(struct epoch_context *ctx)
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{
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struct pf_keth_settings *settings;
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settings = __containerof(ctx, struct pf_keth_settings, epoch_ctx);
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CURVNET_SET(settings->vnet);
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MPASS(settings == V_pf_keth_inactive);
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PF_RULES_WLOCK();
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pf_rollback_eth(V_pf_keth_inactive->ticket);
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PF_RULES_WUNLOCK();
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CURVNET_RESTORE();
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}
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static int
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pf_rollback_eth(uint32_t ticket)
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{
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@ -780,15 +805,20 @@ pf_commit_eth(uint32_t ticket)
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ticket != V_pf_keth_inactive->ticket)
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return (EBUSY);
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PF_RULES_WASSERT();
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pf_eth_calc_skip_steps(&V_pf_keth_inactive->rules);
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settings = V_pf_keth;
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V_pf_keth = V_pf_keth_inactive;
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ck_pr_store_ptr(&V_pf_keth, V_pf_keth_inactive);
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V_pf_keth_inactive = settings;
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V_pf_keth_inactive->ticket = V_pf_keth->ticket;
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/* Clean up inactive rules. */
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return (pf_rollback_eth(ticket));
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/* Clean up inactive rules (i.e. previously active rules), only when
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* we're sure they're no longer used. */
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NET_EPOCH_CALL(pf_rollback_eth_cb, &V_pf_keth_inactive->epoch_ctx);
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return (0);
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}
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#ifdef ALTQ
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@ -154,6 +154,7 @@ pf_init_keth(struct pf_keth_settings *settings)
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TAILQ_INIT(&settings->rules);
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settings->ticket = 0;
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settings->open = 0;
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settings->vnet = curvnet;
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}
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struct pf_kruleset *
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