Date: Mon, 24 Feb 2014 13:09:24 +0900 (JST) From: Hiroki Sato <hrs@FreeBSD.org> To: ianf@clue.co.za Cc: current@FreeBSD.org Subject: Re: netstat: sysctl: net.route.0.0.dump.0: Cannot allocate memory Message-ID: <20140224.130924.1512809959333112659.hrs@allbsd.org> In-Reply-To: <E1WGmTE-0000nr-Us@clue.co.za> References: <E1WGkzK-0000gb-E2@clue.co.za> <E1WGltZ-0000kf-1A@clue.co.za> <E1WGmTE-0000nr-Us@clue.co.za>
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Ian FREISLICH <ianf@clue.co.za> wrote
in <E1WGmTE-0000nr-Us@clue.co.za>:
ia> Hiroki Sato wrote:
ia> > Hm, how about the attached one?
ia> >
ia> > I think the cause is just a race when length of the sysctl's output
ia> > is changed in kernel after the buffer allocation in userspace, not
ia> > memory shortage. Size of the routing table can quickly change.
ia>
ia> You are correct. It's growing at about 9000 entries per second (I
ia> wish it were faster).
ia>
ia> This is what the output looks like now. I guess I'm not the average
ia> case.
Can you try the attached patch? It will attempt to enlarge the
buffer every retry.
-- Hiroki
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Index: route.c
===================================================================
--- route.c (revision 262313)
+++ route.c (working copy)
@@ -69,6 +69,7 @@
#include <sysexits.h>
#include <unistd.h>
#include <err.h>
+#include <errno.h>
#include "netstat.h"
#define kget(p, d) (kread((u_long)(p), (char *)&(d), sizeof (d)))
@@ -560,7 +561,7 @@
char *buf, *next, *lim;
struct rt_msghdr *rtm;
struct sockaddr *sa;
- int fam = 0, ifindex = 0, size;
+ int fam = 0, ifindex = 0, size, count = 0;
struct ifaddrs *ifap, *ifa;
struct sockaddr_dl *sdl;
@@ -600,6 +601,7 @@
freeifaddrs(ifap);
+retry:
mib[0] = CTL_NET;
mib[1] = PF_ROUTE;
mib[2] = 0;
@@ -607,19 +609,27 @@
mib[4] = NET_RT_DUMP;
mib[5] = 0;
mib[6] = fibnum;
- if (sysctl(mib, 7, NULL, &needed, NULL, 0) < 0) {
- err(1, "sysctl: net.route.0.%d.dump.%d estimate", af, fibnum);
+ if (sysctl(mib, nitems(mib), NULL, &needed, NULL, 0) < 0)
+ err(EX_OSERR, "sysctl: net.route.0.%d.dump.%d estimate", af,
+ fibnum);
+ needed += PAGE_SIZE * (count + 1);
+ if ((buf = malloc(needed)) == NULL)
+ errx(EX_OSERR, "malloc(%zd)", needed);
+ if (sysctl(mib, nitems(mib), buf, &needed, NULL, 0) < 0) {
+ if (errno == ENOMEM && count++ < 20) {
+ warnx("Routing table grew, retrying");
+ sleep(1);
+ free(buf);
+ goto retry;
+ } else
+ err(EX_OSERR, "sysctl: net.route.0.%d.dump.%d", af,
+ fibnum);
}
-
- if ((buf = malloc(needed)) == 0) {
- errx(2, "malloc(%lu)", (unsigned long)needed);
- }
- if (sysctl(mib, 6, buf, &needed, NULL, 0) < 0) {
- err(1, "sysctl: net.route.0.%d.dump.%d", af, fibnum);
- }
lim = buf + needed;
for (next = buf; next < lim; next += rtm->rtm_msglen) {
rtm = (struct rt_msghdr *)next;
+ if (rtm->rtm_version != RTM_VERSION)
+ continue;
/*
* Peek inside header to determine AF
*/
@@ -632,6 +642,7 @@
}
p_rtentry_sysctl(rtm);
}
+ free(buf);
}
static void
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