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inpcb: don't return INP_DROPPED entries from pcb lookups

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The in_pcbdrop() KPI, which is used solely by TCP, allows to remove a
pcb from hash list and mark it as dropped.  The comment suggests that
such pcb won't be returned by lookups.  Indeed, every call to
in_pcblookup*() is accompanied by a check for INP_DROPPED.  Do what
comment suggests: never return such pcbs and remove unnecessary checks.

Reviewed by:		tuexen
Differential revision:	https://reviews.freebsd.org/D37061
This commit is contained in:
Gleb Smirnoff 2022-11-08 10:24:39 -08:00
parent b5c3819c7b
commit f567d55f51
4 changed files with 23 additions and 26 deletions
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22
sys/netinet/in_pcb.c
View File

@ -1536,15 +1536,15 @@ in_pcbrele(struct inpcb *inp, const inp_lookup_t lock)
in_pcbrele_rlocked(inp) : in_pcbrele_wlocked(inp));
}
bool
inp_smr_lock(struct inpcb *inp, const inp_lookup_t lock)
static inline bool
_inp_smr_lock(struct inpcb *inp, const inp_lookup_t lock, const int ignflags)
{
MPASS(lock == INPLOOKUP_RLOCKPCB || lock == INPLOOKUP_WLOCKPCB);
SMR_ASSERT_ENTERED(inp->inp_pcbinfo->ipi_smr);
if (__predict_true(inp_trylock(inp, lock))) {
if (__predict_false(inp->inp_flags & INP_FREED)) {
if (__predict_false(inp->inp_flags & ignflags)) {
smr_exit(inp->inp_pcbinfo->ipi_smr);
inp_unlock(inp, lock);
return (false);
@ -1564,7 +1564,7 @@ inp_smr_lock(struct inpcb *inp, const inp_lookup_t lock)
* through in_pcbfree() and has another reference, that
* prevented its release by our in_pcbrele().
*/
if (__predict_false(inp->inp_flags & INP_FREED)) {
if (__predict_false(inp->inp_flags & ignflags)) {
inp_unlock(inp, lock);
return (false);
}
@ -1575,6 +1575,18 @@ inp_smr_lock(struct inpcb *inp, const inp_lookup_t lock)
}
}
bool
inp_smr_lock(struct inpcb *inp, const inp_lookup_t lock)
{
/*
* in_pcblookup() family of functions ignore not only freed entries,
* that may be found due to lockless access to the hash, but dropped
* entries, too.
*/
return (_inp_smr_lock(inp, lock, INP_FREED | INP_DROPPED));
}
/*
* inp_next() - inpcb hash/list traversal iterator
*
@ -1631,7 +1643,7 @@ inp_next(struct inpcb_iterator *ii)
inp = II_LIST_NEXT(inp, hash)) {
if (match != NULL && (match)(inp, ctx) == false)
continue;
if (__predict_true(inp_smr_lock(inp, lock)))
if (__predict_true(_inp_smr_lock(inp, lock, INP_FREED)))
break;
else {
smr_enter(ipi->ipi_smr);

11
sys/netinet/tcp_input.c
View File

@ -937,16 +937,7 @@ tcp_input_with_port(struct mbuf **mp, int *offp, int proto, uint16_t port)
goto dropwithreset;
}
INP_LOCK_ASSERT(inp);
/*
* While waiting for inp lock during the lookup, another thread
* can have dropped the inpcb, in which case we need to loop back
* and try to find a new inpcb to deliver to.
*/
if (inp->inp_flags & INP_DROPPED) {
INP_UNLOCK(inp);
inp = NULL;
goto findpcb;
}
if ((inp->inp_flowtype == M_HASHTYPE_NONE) &&
(M_HASHTYPE_GET(m) != M_HASHTYPE_NONE) &&
((inp->inp_socket == NULL) || !SOLISTENING(inp->inp_socket))) {

4
sys/netinet/tcp_lro.c
View File

@ -1360,9 +1360,7 @@ tcp_lro_flush_tcphpts(struct lro_ctrl *lc, struct lro_entry *le)
tp = intotcpcb(inp);
/* Check if the inp is dead, Jim. */
if (tp == NULL ||
(inp->inp_flags & INP_DROPPED) ||
(tp->t_state == TCPS_TIME_WAIT)) {
if (tp->t_state == TCPS_TIME_WAIT) {
INP_WUNLOCK(inp);
return (TCP_LRO_CANNOT);
}

12
sys/netinet/tcp_subr.c
View File

@ -2878,8 +2878,7 @@ tcp_ctlinput_with_port(struct icmp *icp, uint16_t port)
inp = in_pcblookup(&V_tcbinfo, ip->ip_dst, th->th_dport, ip->ip_src,
th->th_sport, INPLOOKUP_WLOCKPCB, NULL);
if (inp != NULL) {
if (!(inp->inp_flags & INP_DROPPED) &&
!(inp->inp_socket == NULL)) {
if (inp->inp_socket != NULL) {
tp = intotcpcb(inp);
#ifdef TCP_OFFLOAD
if (tp->t_flags & TF_TOE && errno == EMSGSIZE) {
@ -3071,8 +3070,7 @@ tcp6_ctlinput_with_port(struct ip6ctlparam *ip6cp, uint16_t port)
}
m_copydata(m, off, sizeof(tcp_seq), (caddr_t)&icmp_tcp_seq);
if (inp != NULL) {
if (!(inp->inp_flags & INP_DROPPED) &&
!(inp->inp_socket == NULL)) {
if (inp->inp_socket != NULL) {
tp = intotcpcb(inp);
#ifdef TCP_OFFLOAD
if (tp->t_flags & TF_TOE && errno == EMSGSIZE) {
@ -3697,8 +3695,7 @@ sysctl_drop(SYSCTL_HANDLER_ARGS)
#endif
}
if (inp != NULL) {
if ((inp->inp_flags & INP_DROPPED) == 0 &&
!SOLISTENING(inp->inp_socket)) {
if (!SOLISTENING(inp->inp_socket)) {
tp = intotcpcb(inp);
tp = tcp_drop(tp, ECONNABORTED);
if (tp != NULL)
@ -3817,8 +3814,7 @@ sysctl_switch_tls(SYSCTL_HANDLER_ARGS)
}
NET_EPOCH_EXIT(et);
if (inp != NULL) {
if ((inp->inp_flags & INP_DROPPED) != 0 ||
inp->inp_socket == NULL) {
if (inp->inp_socket == NULL) {
error = ECONNRESET;
INP_WUNLOCK(inp);
} else {