On Fri, Sep 15, 2023 at 04:18:13PM +0200, Martin Pieuchot wrote:
> On 11/09/23(Mon) 21:05, Martin Pieuchot wrote:
> > On 06/09/23(Wed) 23:13, Alexander Bluhm wrote:
> > > On Wed, Sep 06, 2023 at 12:23:33PM -0500, Scott Cheloha wrote:
> > > > On Wed, Sep 06, 2023 at 01:04:19PM +0100, Martin Pieuchot wrote:
> > > > > Debugging OOM is hard. UVM uses per-CPU counters and sadly
> > > > > counters_read(9) needs to allocate memory. This is not acceptable in
> > > > > ddb(4). As a result I cannot see the content of UVM counters in OOM
> > > > > situations.
> > > > >
> > > > > Diff below introduces a *_static() variant of counters_read(9) that
> > > > > takes a secondary buffer to avoid calling malloc(9). Is it fine? Do
> > > > > you have a better idea? Should we make it the default or using the
> > > > > stack might be a problem?
> > > >
> > > > Instead of adding a second interface I think we could get away with
> > > > just extending counters_read(9) to take a scratch buffer as an optional
> > > > fourth parameter:
> > > >
> > > > void
> > > > counters_read(struct cpumem *cm, uint64_t *output, unsigned int n,
> > > > uint64_t *scratch);
> > > >
> > > > "scratch"? "temp"? "tmp"?
> > >
> > > scratch is fine for me
> >
> > Fine with me.
>
> Here's a full diff, works for me(tm), ok?
OK bluhm@
> Index: sys/kern/kern_sysctl.c
> ===================================================================
> RCS file: /cvs/src/sys/kern/kern_sysctl.c,v
> retrieving revision 1.418
> diff -u -p -r1.418 kern_sysctl.c
> --- sys/kern/kern_sysctl.c 16 Jul 2023 03:01:31 -0000 1.418
> +++ sys/kern/kern_sysctl.c 15 Sep 2023 13:29:53 -0000
> @@ -519,7 +519,7 @@ kern_sysctl(int *name, u_int namelen, vo
> unsigned int i;
>
> memset(&mbs, 0, sizeof(mbs));
> - counters_read(mbstat, counters, MBSTAT_COUNT);
> + counters_read(mbstat, counters, MBSTAT_COUNT, NULL);
> for (i = 0; i < MBSTAT_TYPES; i++)
> mbs.m_mtypes[i] = counters[i];
>
> Index: sys/kern/subr_evcount.c
> ===================================================================
> RCS file: /cvs/src/sys/kern/subr_evcount.c,v
> retrieving revision 1.15
> diff -u -p -r1.15 subr_evcount.c
> --- sys/kern/subr_evcount.c 5 Dec 2022 08:58:49 -0000 1.15
> +++ sys/kern/subr_evcount.c 15 Sep 2023 14:01:55 -0000
> @@ -101,7 +101,7 @@ evcount_sysctl(int *name, u_int namelen,
> {
> int error = 0, s, nintr, i;
> struct evcount *ec;
> - u_int64_t count;
> + uint64_t count, scratch;
>
> if (newp != NULL)
> return (EPERM);
> @@ -129,7 +129,7 @@ evcount_sysctl(int *name, u_int namelen,
> if (ec == NULL)
> return (ENOENT);
> if (ec->ec_percpu != NULL) {
> - counters_read(ec->ec_percpu, &count, 1);
> + counters_read(ec->ec_percpu, &count, 1, &scratch);
> } else {
> s = splhigh();
> count = ec->ec_count;
> Index: sys/kern/subr_percpu.c
> ===================================================================
> RCS file: /cvs/src/sys/kern/subr_percpu.c,v
> retrieving revision 1.10
> diff -u -p -r1.10 subr_percpu.c
> --- sys/kern/subr_percpu.c 3 Oct 2022 14:10:53 -0000 1.10
> +++ sys/kern/subr_percpu.c 15 Sep 2023 14:16:41 -0000
> @@ -159,17 +159,19 @@ counters_free(struct cpumem *cm, unsigne
> }
>
> void
> -counters_read(struct cpumem *cm, uint64_t *output, unsigned int n)
> +counters_read(struct cpumem *cm, uint64_t *output, unsigned int n,
> + uint64_t *scratch)
> {
> struct cpumem_iter cmi;
> - uint64_t *gen, *counters, *temp;
> + uint64_t *gen, *counters, *temp = scratch;
> uint64_t enter, leave;
> unsigned int i;
>
> for (i = 0; i < n; i++)
> output[i] = 0;
>
> - temp = mallocarray(n, sizeof(uint64_t), M_TEMP, M_WAITOK);
> + if (scratch == NULL)
> + temp = mallocarray(n, sizeof(uint64_t), M_TEMP, M_WAITOK);
>
> gen = cpumem_first(&cmi, cm);
> do {
> @@ -202,7 +204,8 @@ counters_read(struct cpumem *cm, uint64_
> gen = cpumem_next(&cmi, cm);
> } while (gen != NULL);
>
> - free(temp, M_TEMP, n * sizeof(uint64_t));
> + if (scratch == NULL)
> + free(temp, M_TEMP, n * sizeof(uint64_t));
> }
>
> void
> @@ -305,7 +308,8 @@ counters_free(struct cpumem *cm, unsigne
> }
>
> void
> -counters_read(struct cpumem *cm, uint64_t *output, unsigned int n)
> +counters_read(struct cpumem *cm, uint64_t *output, unsigned int n,
> + uint64_t *scratch)
> {
> uint64_t *counters;
> unsigned int i;
> Index: sys/net/pfkeyv2_convert.c
> ===================================================================
> RCS file: /cvs/src/sys/net/pfkeyv2_convert.c,v
> retrieving revision 1.80
> diff -u -p -r1.80 pfkeyv2_convert.c
> --- sys/net/pfkeyv2_convert.c 7 Aug 2023 03:35:06 -0000 1.80
> +++ sys/net/pfkeyv2_convert.c 15 Sep 2023 13:33:37 -0000
> @@ -992,7 +992,7 @@ export_counter(void **p, struct tdb *tdb
> uint64_t counters[tdb_ncounters];
> struct sadb_x_counter *scnt = (struct sadb_x_counter *)*p;
>
> - counters_read(tdb->tdb_counters, counters, tdb_ncounters);
> + counters_read(tdb->tdb_counters, counters, tdb_ncounters, NULL);
>
> scnt->sadb_x_counter_len = sizeof(struct sadb_x_counter) /
> sizeof(uint64_t);
> Index: sys/net/if_pfsync.c
> ===================================================================
> RCS file: /cvs/src/sys/net/if_pfsync.c,v
> retrieving revision 1.320
> diff -u -p -r1.320 if_pfsync.c
> --- sys/net/if_pfsync.c 18 Aug 2023 08:03:57 -0000 1.320
> +++ sys/net/if_pfsync.c 15 Sep 2023 13:33:42 -0000
> @@ -3339,7 +3339,7 @@ pfsync_sysctl_pfsyncstat(void *oldp, siz
> CTASSERT(sizeof(pfsyncstat) == (pfsyncs_ncounters * sizeof(uint64_t)));
> memset(&pfsyncstat, 0, sizeof pfsyncstat);
> counters_read(pfsynccounters, (uint64_t *)&pfsyncstat,
> - pfsyncs_ncounters);
> + pfsyncs_ncounters, NULL);
> return (sysctl_rdstruct(oldp, oldlenp, newp,
> &pfsyncstat, sizeof(pfsyncstat)));
> }
> Index: sys/net/if_etherip.c
> ===================================================================
> RCS file: /cvs/src/sys/net/if_etherip.c,v
> retrieving revision 1.50
> diff -u -p -r1.50 if_etherip.c
> --- sys/net/if_etherip.c 28 Feb 2022 00:12:11 -0000 1.50
> +++ sys/net/if_etherip.c 15 Sep 2023 13:33:58 -0000
> @@ -789,7 +789,7 @@ etherip_sysctl_etheripstat(void *oldp, s
> sizeof(uint64_t)));
> memset(ðeripstat, 0, sizeof etheripstat);
> counters_read(etheripcounters, (uint64_t *)ðeripstat,
> - etherips_ncounters);
> + etherips_ncounters, NULL);
> return (sysctl_rdstruct(oldp, oldlenp, newp, ðeripstat,
> sizeof(etheripstat)));
> }
> Index: sys/net/if.c
> ===================================================================
> RCS file: /cvs/src/sys/net/if.c,v
> retrieving revision 1.707
> diff -u -p -r1.707 if.c
> --- sys/net/if.c 18 Aug 2023 08:10:16 -0000 1.707
> +++ sys/net/if.c 15 Sep 2023 13:34:06 -0000
> @@ -2797,7 +2797,8 @@ if_getdata(struct ifnet *ifp, struct if_
> if (ifp->if_counters != NULL) {
> uint64_t counters[ifc_ncounters];
>
> - counters_read(ifp->if_counters, counters, nitems(counters));
> + counters_read(ifp->if_counters, counters, nitems(counters),
> + NULL);
>
> data->ifi_ipackets += counters[ifc_ipackets];
> data->ifi_ierrors += counters[ifc_ierrors];
> Index: sys/net/pipex.c
> ===================================================================
> RCS file: /cvs/src/sys/net/pipex.c,v
> retrieving revision 1.148
> diff -u -p -r1.148 pipex.c
> --- sys/net/pipex.c 30 Aug 2022 19:42:29 -0000 1.148
> +++ sys/net/pipex.c 15 Sep 2023 13:34:11 -0000
> @@ -558,7 +558,7 @@ pipex_export_session_stats(struct pipex_
>
> memset(stats, 0, sizeof(*stats));
>
> - counters_read(session->stat_counters, counters, pxc_ncounters);
> + counters_read(session->stat_counters, counters, pxc_ncounters, NULL);
> stats->ipackets = counters[pxc_ipackets];
> stats->ierrors = counters[pxc_ierrors];
> stats->ibytes = counters[pxc_ibytes];
> Index: sys/net/rtsock.c
> ===================================================================
> RCS file: /cvs/src/sys/net/rtsock.c,v
> retrieving revision 1.369
> diff -u -p -r1.369 rtsock.c
> --- sys/net/rtsock.c 28 Jul 2023 09:33:16 -0000 1.369
> +++ sys/net/rtsock.c 15 Sep 2023 13:34:14 -0000
> @@ -2245,7 +2245,7 @@ sysctl_rtable_rtstat(void *oldp, size_t
>
> CTASSERT(sizeof(rtstat) == (nitems(counters) * sizeof(uint32_t)));
> memset(&rtstat, 0, sizeof rtstat);
> - counters_read(rtcounters, counters, nitems(counters));
> + counters_read(rtcounters, counters, nitems(counters), NULL);
>
> for (i = 0; i < nitems(counters); i++)
> words[i] = (uint32_t)counters[i];
> Index: sys/netinet/igmp.c
> ===================================================================
> RCS file: /cvs/src/sys/netinet/igmp.c,v
> retrieving revision 1.82
> diff -u -p -r1.82 igmp.c
> --- sys/netinet/igmp.c 8 Sep 2022 10:22:06 -0000 1.82
> +++ sys/netinet/igmp.c 15 Sep 2023 13:34:20 -0000
> @@ -687,7 +687,7 @@ igmp_sysctl_igmpstat(void *oldp, size_t
>
> CTASSERT(sizeof(igmpstat) == (nitems(counters) * sizeof(u_long)));
> memset(&igmpstat, 0, sizeof igmpstat);
> - counters_read(igmpcounters, counters, nitems(counters));
> + counters_read(igmpcounters, counters, nitems(counters), NULL);
>
> for (i = 0; i < nitems(counters); i++)
> words[i] = (u_long)counters[i];
> Index: sys/netinet/ip_carp.c
> ===================================================================
> RCS file: /cvs/src/sys/netinet/ip_carp.c,v
> retrieving revision 1.357
> diff -u -p -r1.357 ip_carp.c
> --- sys/netinet/ip_carp.c 16 May 2023 14:32:54 -0000 1.357
> +++ sys/netinet/ip_carp.c 15 Sep 2023 13:34:35 -0000
> @@ -749,7 +749,8 @@ carp_sysctl_carpstat(void *oldp, size_t
>
> CTASSERT(sizeof(carpstat) == (carps_ncounters * sizeof(uint64_t)));
> memset(&carpstat, 0, sizeof carpstat);
> - counters_read(carpcounters, (uint64_t *)&carpstat, carps_ncounters);
> + counters_read(carpcounters, (uint64_t *)&carpstat, carps_ncounters,
> + NULL);
> return (sysctl_rdstruct(oldp, oldlenp, newp,
> &carpstat, sizeof(carpstat)));
> }
> Index: sys/netinet/ip_divert.c
> ===================================================================
> RCS file: /cvs/src/sys/netinet/ip_divert.c,v
> retrieving revision 1.91
> diff -u -p -r1.91 ip_divert.c
> --- sys/netinet/ip_divert.c 13 May 2023 13:35:17 -0000 1.91
> +++ sys/netinet/ip_divert.c 15 Sep 2023 13:34:25 -0000
> @@ -350,7 +350,7 @@ divert_sysctl_divstat(void *oldp, size_t
>
> CTASSERT(sizeof(divstat) == (nitems(counters) * sizeof(u_long)));
> memset(&divstat, 0, sizeof divstat);
> - counters_read(divcounters, counters, nitems(counters));
> + counters_read(divcounters, counters, nitems(counters), NULL);
>
> for (i = 0; i < nitems(counters); i++)
> words[i] = (u_long)counters[i];
> Index: sys/netinet/ip_icmp.c
> ===================================================================
> RCS file: /cvs/src/sys/netinet/ip_icmp.c,v
> retrieving revision 1.191
> diff -u -p -r1.191 ip_icmp.c
> --- sys/netinet/ip_icmp.c 5 May 2022 13:57:40 -0000 1.191
> +++ sys/netinet/ip_icmp.c 15 Sep 2023 13:34:40 -0000
> @@ -917,7 +917,7 @@ icmp_sysctl_icmpstat(void *oldp, size_t
>
> CTASSERT(sizeof(icmpstat) == (nitems(counters) * sizeof(u_long)));
> memset(&icmpstat, 0, sizeof icmpstat);
> - counters_read(icmpcounters, counters, nitems(counters));
> + counters_read(icmpcounters, counters, nitems(counters), NULL);
>
> for (i = 0; i < nitems(counters); i++)
> words[i] = (u_long)counters[i];
> Index: sys/netinet/ip_input.c
> ===================================================================
> RCS file: /cvs/src/sys/netinet/ip_input.c,v
> retrieving revision 1.386
> diff -u -p -r1.386 ip_input.c
> --- sys/netinet/ip_input.c 6 Sep 2023 11:09:43 -0000 1.386
> +++ sys/netinet/ip_input.c 15 Sep 2023 13:34:45 -0000
> @@ -1747,7 +1747,7 @@ ip_sysctl_ipstat(void *oldp, size_t *old
>
> CTASSERT(sizeof(ipstat) == (nitems(counters) * sizeof(u_long)));
> memset(&ipstat, 0, sizeof ipstat);
> - counters_read(ipcounters, counters, nitems(counters));
> + counters_read(ipcounters, counters, nitems(counters), NULL);
>
> for (i = 0; i < nitems(counters); i++)
> words[i] = (u_long)counters[i];
> Index: sys/netinet/ip_ipip.c
> ===================================================================
> RCS file: /cvs/src/sys/netinet/ip_ipip.c,v
> retrieving revision 1.98
> diff -u -p -r1.98 ip_ipip.c
> --- sys/netinet/ip_ipip.c 2 Jan 2022 22:36:04 -0000 1.98
> +++ sys/netinet/ip_ipip.c 15 Sep 2023 13:34:56 -0000
> @@ -573,7 +573,8 @@ ipip_sysctl_ipipstat(void *oldp, size_t
>
> CTASSERT(sizeof(ipipstat) == (ipips_ncounters * sizeof(uint64_t)));
> memset(&ipipstat, 0, sizeof ipipstat);
> - counters_read(ipipcounters, (uint64_t *)&ipipstat, ipips_ncounters);
> + counters_read(ipipcounters, (uint64_t *)&ipipstat, ipips_ncounters,
> + NULL);
> return (sysctl_rdstruct(oldp, oldlenp, newp,
> &ipipstat, sizeof(ipipstat)));
> }
> Index: sys/netinet/ipsec_input.c
> ===================================================================
> RCS file: /cvs/src/sys/netinet/ipsec_input.c,v
> retrieving revision 1.205
> diff -u -p -r1.205 ipsec_input.c
> --- sys/netinet/ipsec_input.c 7 Aug 2023 03:43:57 -0000 1.205
> +++ sys/netinet/ipsec_input.c 15 Sep 2023 13:35:24 -0000
> @@ -664,7 +664,7 @@ esp_sysctl_espstat(void *oldp, size_t *o
>
> CTASSERT(sizeof(espstat) == (esps_ncounters * sizeof(uint64_t)));
> memset(&espstat, 0, sizeof espstat);
> - counters_read(espcounters, (uint64_t *)&espstat, esps_ncounters);
> + counters_read(espcounters, (uint64_t *)&espstat, esps_ncounters, NULL);
> return (sysctl_rdstruct(oldp, oldlenp, newp, &espstat,
> sizeof(espstat)));
> }
> @@ -698,7 +698,7 @@ ah_sysctl_ahstat(void *oldp, size_t *old
>
> CTASSERT(sizeof(ahstat) == (ahs_ncounters * sizeof(uint64_t)));
> memset(&ahstat, 0, sizeof ahstat);
> - counters_read(ahcounters, (uint64_t *)&ahstat, ahs_ncounters);
> + counters_read(ahcounters, (uint64_t *)&ahstat, ahs_ncounters, NULL);
> return (sysctl_rdstruct(oldp, oldlenp, newp, &ahstat, sizeof(ahstat)));
> }
>
> @@ -733,7 +733,7 @@ ipcomp_sysctl_ipcompstat(void *oldp, siz
> CTASSERT(sizeof(ipcompstat) == (ipcomps_ncounters * sizeof(uint64_t)));
> memset(&ipcompstat, 0, sizeof ipcompstat);
> counters_read(ipcompcounters, (uint64_t *)&ipcompstat,
> - ipcomps_ncounters);
> + ipcomps_ncounters, NULL);
> return (sysctl_rdstruct(oldp, oldlenp, newp, &ipcompstat,
> sizeof(ipcompstat)));
> }
> @@ -745,7 +745,8 @@ ipsec_sysctl_ipsecstat(void *oldp, size_
>
> CTASSERT(sizeof(ipsecstat) == (ipsec_ncounters * sizeof(uint64_t)));
> memset(&ipsecstat, 0, sizeof ipsecstat);
> - counters_read(ipseccounters, (uint64_t *)&ipsecstat, ipsec_ncounters);
> + counters_read(ipseccounters, (uint64_t *)&ipsecstat, ipsec_ncounters,
> + NULL);
> return (sysctl_rdstruct(oldp, oldlenp, newp, &ipsecstat,
> sizeof(ipsecstat)));
> }
> Index: sys/netinet/tcp_usrreq.c
> ===================================================================
> RCS file: /cvs/src/sys/netinet/tcp_usrreq.c,v
> retrieving revision 1.221
> diff -u -p -r1.221 tcp_usrreq.c
> --- sys/netinet/tcp_usrreq.c 6 Jul 2023 09:15:24 -0000 1.221
> +++ sys/netinet/tcp_usrreq.c 15 Sep 2023 13:47:13 -0000
> @@ -1237,7 +1237,7 @@ tcp_sysctl_tcpstat(void *oldp, size_t *o
> #define ASSIGN(field) do { tcpstat.field = counters[i++]; } while (0)
>
> memset(&tcpstat, 0, sizeof tcpstat);
> - counters_read(tcpcounters, counters, nitems(counters));
> + counters_read(tcpcounters, counters, nitems(counters), NULL);
> ASSIGN(tcps_connattempt);
> ASSIGN(tcps_accepts);
> ASSIGN(tcps_connects);
> Index: sys/netinet/udp_usrreq.c
> ===================================================================
> RCS file: /cvs/src/sys/netinet/udp_usrreq.c,v
> retrieving revision 1.305
> diff -u -p -r1.305 udp_usrreq.c
> --- sys/netinet/udp_usrreq.c 22 Jan 2023 12:05:44 -0000 1.305
> +++ sys/netinet/udp_usrreq.c 15 Sep 2023 13:47:17 -0000
> @@ -1314,7 +1314,7 @@ udp_sysctl_udpstat(void *oldp, size_t *o
>
> CTASSERT(sizeof(udpstat) == (nitems(counters) * sizeof(u_long)));
> memset(&udpstat, 0, sizeof udpstat);
> - counters_read(udpcounters, counters, nitems(counters));
> + counters_read(udpcounters, counters, nitems(counters), NULL);
>
> for (i = 0; i < nitems(counters); i++)
> words[i] = (u_long)counters[i];
> Index: sys/netinet6/icmp6.c
> ===================================================================
> RCS file: /cvs/src/sys/netinet6/icmp6.c,v
> retrieving revision 1.248
> diff -u -p -r1.248 icmp6.c
> --- sys/netinet6/icmp6.c 5 Apr 2023 21:51:47 -0000 1.248
> +++ sys/netinet6/icmp6.c 15 Sep 2023 13:46:12 -0000
> @@ -1870,7 +1870,8 @@ icmp6_sysctl_icmp6stat(void *oldp, size_
>
> CTASSERT(sizeof(*icmp6stat) == icp6s_ncounters * sizeof(uint64_t));
> icmp6stat = malloc(sizeof(*icmp6stat), M_TEMP, M_WAITOK|M_ZERO);
> - counters_read(icmp6counters, (uint64_t *)icmp6stat, icp6s_ncounters);
> + counters_read(icmp6counters, (uint64_t *)icmp6stat, icp6s_ncounters,
> + NULL);
> ret = sysctl_rdstruct(oldp, oldlenp, newp,
> icmp6stat, sizeof(*icmp6stat));
> free(icmp6stat, M_TEMP, sizeof(*icmp6stat));
> Index: sys/netinet6/ip6_divert.c
> ===================================================================
> RCS file: /cvs/src/sys/netinet6/ip6_divert.c,v
> retrieving revision 1.89
> diff -u -p -r1.89 ip6_divert.c
> --- sys/netinet6/ip6_divert.c 4 Apr 2023 10:12:03 -0000 1.89
> +++ sys/netinet6/ip6_divert.c 15 Sep 2023 13:46:15 -0000
> @@ -358,7 +358,7 @@ divert6_sysctl_div6stat(void *oldp, size
>
> CTASSERT(sizeof(div6stat) == (nitems(counters) * sizeof(u_long)));
>
> - counters_read(div6counters, counters, nitems(counters));
> + counters_read(div6counters, counters, nitems(counters), NULL);
>
> for (i = 0; i < nitems(counters); i++)
> words[i] = (u_long)counters[i];
> Index: sys/netinet6/ip6_input.c
> ===================================================================
> RCS file: /cvs/src/sys/netinet6/ip6_input.c,v
> retrieving revision 1.255
> diff -u -p -r1.255 ip6_input.c
> --- sys/netinet6/ip6_input.c 6 Sep 2023 11:09:43 -0000 1.255
> +++ sys/netinet6/ip6_input.c 15 Sep 2023 13:46:21 -0000
> @@ -1466,7 +1466,7 @@ ip6_sysctl_ip6stat(void *oldp, size_t *o
> CTASSERT(sizeof(*ip6stat) == (ip6s_ncounters * sizeof(uint64_t)));
>
> ip6stat = malloc(sizeof(*ip6stat), M_TEMP, M_WAITOK);
> - counters_read(ip6counters, (uint64_t *)ip6stat, ip6s_ncounters);
> + counters_read(ip6counters, (uint64_t *)ip6stat, ip6s_ncounters, NULL);
> ret = sysctl_rdstruct(oldp, oldlenp, newp,
> ip6stat, sizeof(*ip6stat));
> free(ip6stat, M_TEMP, sizeof(*ip6stat));
> Index: sys/netinet6/raw_ip6.c
> ===================================================================
> RCS file: /cvs/src/sys/netinet6/raw_ip6.c,v
> retrieving revision 1.172
> diff -u -p -r1.172 raw_ip6.c
> --- sys/netinet6/raw_ip6.c 22 Jan 2023 12:05:44 -0000 1.172
> +++ sys/netinet6/raw_ip6.c 15 Sep 2023 13:46:24 -0000
> @@ -784,7 +784,8 @@ rip6_sysctl_rip6stat(void *oldp, size_t
> struct rip6stat rip6stat;
>
> CTASSERT(sizeof(rip6stat) == rip6s_ncounters * sizeof(uint64_t));
> - counters_read(rip6counters, (uint64_t *)&rip6stat, rip6s_ncounters);
> + counters_read(rip6counters, (uint64_t *)&rip6stat, rip6s_ncounters,
> + NULL);
>
> return (sysctl_rdstruct(oldp, oldplen, newp,
> &rip6stat, sizeof(rip6stat)));
> Index: sys/sys/percpu.h
> ===================================================================
> RCS file: /cvs/src/sys/sys/percpu.h,v
> retrieving revision 1.8
> diff -u -p -r1.8 percpu.h
> --- sys/sys/percpu.h 28 Aug 2018 15:15:02 -0000 1.8
> +++ sys/sys/percpu.h 15 Sep 2023 13:36:07 -0000
> @@ -113,7 +113,8 @@ static struct {
> \
> struct cpumem *counters_alloc(unsigned int);
> struct cpumem *counters_alloc_ncpus(struct cpumem *, unsigned int);
> void counters_free(struct cpumem *, unsigned int);
> -void counters_read(struct cpumem *, uint64_t *, unsigned int);
> +void counters_read(struct cpumem *, uint64_t *, unsigned int,
> + uint64_t *);
> void counters_zero(struct cpumem *, unsigned int);
>
> static inline uint64_t *
> Index: sys/uvm/uvm_meter.c
> ===================================================================
> RCS file: /cvs/src/sys/uvm/uvm_meter.c,v
> retrieving revision 1.49
> diff -u -p -r1.49 uvm_meter.c
> --- sys/uvm/uvm_meter.c 18 Aug 2023 09:18:52 -0000 1.49
> +++ sys/uvm/uvm_meter.c 15 Sep 2023 13:33:33 -0000
> @@ -249,11 +249,12 @@ uvm_total(struct vmtotal *totalp)
> void
> uvmexp_read(struct uvmexp *uexp)
> {
> - uint64_t counters[exp_ncounters];
> + uint64_t counters[exp_ncounters], scratch[exp_ncounters];
>
> memcpy(uexp, &uvmexp, sizeof(*uexp));
>
> - counters_read(uvmexp_counters, counters, exp_ncounters);
> + counters_read(uvmexp_counters, counters, exp_ncounters,
> + scratch);
>
> /* stat counters */
> uexp->faults = (int)counters[faults];
> Index: share/man/man9/counters_alloc.9
> ===================================================================
> RCS file: /cvs/src/share/man/man9/counters_alloc.9,v
> retrieving revision 1.12
> diff -u -p -r1.12 counters_alloc.9
> --- share/man/man9/counters_alloc.9 20 Feb 2022 23:11:01 -0000 1.12
> +++ share/man/man9/counters_alloc.9 15 Sep 2023 14:08:55 -0000
> @@ -64,6 +64,7 @@
> .Fa "struct cpumem *cm"
> .Fa "uint64_t *counters"
> .Fa "unsigned int ncounters"
> +.Fa "uint64_t *scratch"
> .Fc
> .Ft void
> .Fn counters_zero "struct cpumem *cm" "unsigned int ncounters"
> @@ -191,6 +192,12 @@ The sum of the counters is written to th
> array.
> The number of counters is specified with
> .Fa ncounters .
> +.Fa scratch
> +may point to a buffer used to temporarily hold
> +.Fa counters .
> +If
> +.Dv NULL ,
> +one will be dynamically allocated and freed.
> .Pp
> .Fn counters_zero
> iterates over each CPU's set of counters referenced by
