avoid reading data when enumerating kstats.

this means we can reliably read the provider/instance/name/unit
tuple, which should avoid "duplicate kstat entry" when multiple
kstat read handlers have issues.

found on a box with multiple rge interfaces, which have hardware
backed kstats that can only be read when the interface is up.

diff --git a/usr.bin/kstat/kstat.c b/usr.bin/kstat/kstat.c
index cd9a9a7..e396e08 100644 (file)
--- a/usr.bin/kstat/kstat.c
+++ b/usr.bin/kstat/kstat.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: kstat.c,v 1.12 2023/11/16 02:45:54 dlg Exp $ */
+/* $OpenBSD: kstat.c,v 1.13 2023/11/16 03:17:34 dlg Exp $ */
 
 /*
  * Copyright (c) 2020 David Gwynne <dlg@openbsd.org>
@@ -193,6 +193,7 @@ main(int argc, char *argv[])
                err(1, "kstat version");
 
        kstat_list(&kt, fd, version, &kfs);
+       kstat_read(&kt, fd);
        kstat_print(&kt);
 
        if (wait == 0)
@@ -516,7 +517,6 @@ kstat_list(struct kstat_tree *kt, int fd, unsigned int version,
 {
        struct kstat_entry *kse;
        struct kstat_req *ksreq;
-       size_t len;
        uint64_t id = 0;
 
        for (;;) {
@@ -529,19 +529,12 @@ kstat_list(struct kstat_tree *kt, int fd, unsigned int version,
                ksreq->ks_version = version;
                ksreq->ks_id = ++id;
 
-               ksreq->ks_datalen = len = 64; /* magic */
-               ksreq->ks_data = malloc(len);
-               if (ksreq->ks_data == NULL)
-                       err(1, "data alloc");
-
                if (ioctl(fd, KSTATIOC_NFIND_ID, ksreq) == -1) {
                        if (errno == ENOENT) {
                                free(ksreq->ks_data);
                                free(kse);
                                break;
                        }
-
-                       kse->serrno = errno;
                } else
                        id = ksreq->ks_id;
 
@@ -554,18 +547,9 @@ kstat_list(struct kstat_tree *kt, int fd, unsigned int version,
                if (RBT_INSERT(kstat_tree, kt, kse) != NULL)
                        errx(1, "duplicate kstat entry");
 
-               if (kse->serrno != 0)
-                       continue;
-
-               while (ksreq->ks_datalen > len) {
-                       len = ksreq->ks_datalen;
-                       ksreq->ks_data = realloc(ksreq->ks_data, len);
-                       if (ksreq->ks_data == NULL)
-                               err(1, "data resize (%zu)", len);
-
-                       if (ioctl(fd, KSTATIOC_FIND_ID, ksreq) == -1)
-                               err(1, "find id %llu", ksreq->ks_id);
-               }
+               ksreq->ks_data = malloc(ksreq->ks_datalen);
+               if (ksreq->ks_data == NULL)
+                       err(1, "kstat data alloc");
        }
 }
 
@@ -581,7 +565,8 @@ kstat_print(struct kstat_tree *kt)
                    ksreq->ks_provider, ksreq->ks_instance,
                    ksreq->ks_name, ksreq->ks_unit);
                if (kse->serrno != 0) {
-                       printf("\t%s\n", strerror(kse->serrno));
+                       printf("\tkstat read error: %s\n",
+                           strerror(kse->serrno));
                        continue;
                }
                switch (ksreq->ks_type) {
@@ -607,9 +592,10 @@ kstat_read(struct kstat_tree *kt, int fd)
        struct kstat_req *ksreq;
 
        RBT_FOREACH(kse, kstat_tree, kt) {
+               kse->serrno = 0;
                ksreq = &kse->kstat;
                if (ioctl(fd, KSTATIOC_FIND_ID, ksreq) == -1)
-                       err(1, "update id %llu", ksreq->ks_id);
+                       kse->serrno = errno;
        }
 }