On 6/22/20 11:56 PM, Andrii Nakryiko wrote:
On Mon, Jun 22, 2020 at 5:38 PM Yonghong Song <yhs@xxxxxx> wrote:
In my VM, I got identical result compared to /proc/net/{tcp,tcp6}.
For tcp6:
$ cat /proc/net/tcp6
sl local_address remote_address st tx_queue rx_queue tr tm->when retrnsmt uid timeout inode
0: 00000000000000000000000000000000:0016 00000000000000000000000000000000:0000 0A 00000000:00000000 00:00000001 00000000 0 0 17955 1 000000003eb3102e 100 0 0 10 0
$ cat /sys/fs/bpf/p1
sl local_address remote_address st tx_queue rx_queue tr tm->when retrnsmt uid timeout inode
0: 00000000000000000000000000000000:0016 00000000000000000000000000000000:0000 0A 00000000:00000000 00:00000000 00000000 0 0 17955 1 000000003eb3102e 100 0 0 10 0
For tcp:
$ cat /proc/net/tcp
sl local_address rem_address st tx_queue rx_queue tr tm->when retrnsmt uid timeout inode
0: 00000000:0016 00000000:0000 0A 00000000:00000000 00:00000000 00000000 0 0 2666 1 000000007152e43f 100 0 0 10 0
$ cat /sys/fs/bpf/p2
sl local_address remote_address st tx_queue rx_queue tr tm->when retrnsmt uid timeout inode
1: 00000000:0016 00000000:0000 0A 00000000:00000000 00:00000000 00000000 0 0 2666 1 000000007152e43f 100 0 0 10 0
Signed-off-by: Yonghong Song <yhs@xxxxxx>
---
Looks reasonable, to the extent possible ;)
Acked-by: Andrii Nakryiko <andriin@xxxxxx>
tools/testing/selftests/bpf/progs/bpf_iter.h | 15 ++
.../selftests/bpf/progs/bpf_iter_tcp4.c | 235 ++++++++++++++++
.../selftests/bpf/progs/bpf_iter_tcp6.c | 250 ++++++++++++++++++
3 files changed, 500 insertions(+)
create mode 100644 tools/testing/selftests/bpf/progs/bpf_iter_tcp4.c
create mode 100644 tools/testing/selftests/bpf/progs/bpf_iter_tcp6.c
[...]
+static int hlist_unhashed_lockless(const struct hlist_node *h)
+{
+ return !(h->pprev);
+}
+
+static int timer_pending(const struct timer_list * timer)
+{
+ return !hlist_unhashed_lockless(&timer->entry);
+}
+
+extern unsigned CONFIG_HZ __kconfig __weak;
Why the __weak? We expect to have /proc/kconfig.gz in other tests
anyway? __weak will make CONFIG_HZ to be a zero and you'll get a bunch
of divisions by zero.
Make sense. Will change.
+
+#define USER_HZ 100
+#define NSEC_PER_SEC 1000000000ULL
+static clock_t jiffies_to_clock_t(unsigned long x)
+{
+ /* The implementation here tailored to a particular
+ * setting of USER_HZ.
+ */
+ u64 tick_nsec = (NSEC_PER_SEC + CONFIG_HZ/2) / CONFIG_HZ;
+ u64 user_hz_nsec = NSEC_PER_SEC / USER_HZ;
+
+ if ((tick_nsec % user_hz_nsec) == 0) {
+ if (CONFIG_HZ < USER_HZ)
+ return x * (USER_HZ / CONFIG_HZ);
+ else
+ return x / (CONFIG_HZ / USER_HZ);
+ }
+ return x * tick_nsec/user_hz_nsec;
+}
+
[...]
+ if (sk_common->skc_family != AF_INET)
+ return 0;
+
+ tp = bpf_skc_to_tcp_sock(sk_common);
+ if (tp) {
+ return dump_tcp_sock(seq, tp, uid, seq_num);
+ }
nit: unnecessary {}
+
+ tw = bpf_skc_to_tcp_timewait_sock(sk_common);
+ if (tw)
+ return dump_tw_sock(seq, tw, uid, seq_num);
+
+ req = bpf_skc_to_tcp_request_sock(sk_common);
+ if (req)
+ return dump_req_sock(seq, req, uid, seq_num);
+
+ return 0;
+}
[...]
+static int timer_pending(const struct timer_list * timer)
+{
+ return !hlist_unhashed_lockless(&timer->entry);
+}
+
+extern unsigned CONFIG_HZ __kconfig __weak;
same about __weak here
+
+#define USER_HZ 100
+#define NSEC_PER_SEC 1000000000ULL
+static clock_t jiffies_to_clock_t(unsigned long x)
+{
+ /* The implementation here tailored to a particular
+ * setting of USER_HZ.
+ */
+ u64 tick_nsec = (NSEC_PER_SEC + CONFIG_HZ/2) / CONFIG_HZ;
+ u64 user_hz_nsec = NSEC_PER_SEC / USER_HZ;
+
+ if ((tick_nsec % user_hz_nsec) == 0) {
+ if (CONFIG_HZ < USER_HZ)
+ return x * (USER_HZ / CONFIG_HZ);
+ else
+ return x / (CONFIG_HZ / USER_HZ);
+ }
+ return x * tick_nsec/user_hz_nsec;
+}
nit: jiffies_to_clock_t() implementation looks like an overkill for
this use case... Would it be just `x / CONFIG_HZ * NSEC_PER_SEC` with
some potential rounding error?
We really want to have the output the same as /proc/net/{tcp,tcp6}.
Otherwise, it may cause confusion when comparing bpf_iter_tcp[6] outputs
vs. /proc/net/tcp[6] outputs.
+
+static clock_t jiffies_delta_to_clock_t(long delta)
+{
+ if (delta <= 0)
+ return 0;
+
+ return jiffies_to_clock_t(delta);
+}
+
[...]
