tipc: enable tracepoints in tipc

As for the sake of debugging/tracing, the commit enables tracepoints in
TIPC along with some general trace_events as shown below. It also
defines some 'tipc_*_dump()' functions that allow to dump TIPC object
data whenever needed, that is, for general debug purposes, ie. not just
for the trace_events.

The following trace_events are now available:

- trace_tipc_skb_dump(): allows to trace and dump TIPC msg & skb data,
  e.g. message type, user, droppable, skb truesize, cloned skb, etc.

- trace_tipc_list_dump(): allows to trace and dump any TIPC buffers or
  queues, e.g. TIPC link transmq, socket receive queue, etc.

- trace_tipc_sk_dump(): allows to trace and dump TIPC socket data, e.g.
  sk state, sk type, connection type, rmem_alloc, socket queues, etc.

- trace_tipc_link_dump(): allows to trace and dump TIPC link data, e.g.
  link state, silent_intv_cnt, gap, bc_gap, link queues, etc.

- trace_tipc_node_dump(): allows to trace and dump TIPC node data, e.g.
  node state, active links, capabilities, link entries, etc.

How to use:
Put the trace functions at any places where we want to dump TIPC data
or events.

Note:
a) The dump functions will generate raw data only, that is, to offload
the trace event's processing, it can require a tool or script to parse
the data but this should be simple.

b) The trace_tipc_*_dump() should be reserved for a failure cases only
(e.g. the retransmission failure case) or where we do not expect to
happen too often, then we can consider enabling these events by default
since they will almost not take any effects under normal conditions,
but once the rare condition or failure occurs, we get the dumped data
fully for post-analysis.

For other trace purposes, we can reuse these trace classes as template
but different events.

c) A trace_event is only effective when we enable it. To enable the
TIPC trace_events, echo 1 to 'enable' files in the events/tipc/
directory in the 'debugfs' file system. Normally, they are located at:

/sys/kernel/debug/tracing/events/tipc/

For example:

To enable the tipc_link_dump event:

echo 1 > /sys/kernel/debug/tracing/events/tipc/tipc_link_dump/enable

To enable all the TIPC trace_events:

echo 1 > /sys/kernel/debug/tracing/events/tipc/enable

To collect the trace data:

cat trace

or

cat trace_pipe > /trace.out &

To disable all the TIPC trace_events:

echo 0 > /sys/kernel/debug/tracing/events/tipc/enable

To clear the trace buffer:

echo > trace

d) Like the other trace_events, the feature like 'filter' or 'trigger'
is also usable for the tipc trace_events.
For more details, have a look at:

Documentation/trace/ftrace.txt

MAINTAINERS | add two new files 'trace.h' & 'trace.c' in tipc

Acked-by: Ying Xue <ying.xue@windriver.com>
Tested-by: Ying Xue <ying.xue@windriver.com>
Acked-by: Jon Maloy <jon.maloy@ericsson.com>
Signed-off-by: Tuong Lien <tuong.t.lien@dektech.com.au>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 120 insertions, 0 deletions

diff --git a/net/tipc/link.c b/net/tipc/link.c
index 9e265eb89726..668dab529021 100644
--- a/net/tipc/link.c
+++ b/net/tipc/link.c
@@ -43,6 +43,7 @@
 #include "discover.h"
 #include "netlink.h"
 #include "monitor.h"
+#include "trace.h"
 
 #include <linux/pkt_sched.h>
 
@@ -2222,3 +2223,122 @@ void tipc_link_set_abort_limit(struct tipc_link *l, u32 limit)
 {
         l->abort_limit = limit;
 }
+
+char *tipc_link_name_ext(struct tipc_link *l, char *buf)
+{
+        if (!l)
+                scnprintf(buf, TIPC_MAX_LINK_NAME, "null");
+        else if (link_is_bc_sndlink(l))
+                scnprintf(buf, TIPC_MAX_LINK_NAME, "broadcast-sender");
+        else if (link_is_bc_rcvlink(l))
+                scnprintf(buf, TIPC_MAX_LINK_NAME,
+                          "broadcast-receiver, peer %x", l->addr);
+        else
+                memcpy(buf, l->name, TIPC_MAX_LINK_NAME);
+
+        return buf;
+}
+
+/**
+ * tipc_link_dump - dump TIPC link data
+ * @l: tipc link to be dumped
+ * @dqueues: bitmask to decide if any link queue to be dumped?
+ *           - TIPC_DUMP_NONE: don't dump link queues
+ *           - TIPC_DUMP_TRANSMQ: dump link transmq queue
+ *           - TIPC_DUMP_BACKLOGQ: dump link backlog queue
+ *           - TIPC_DUMP_DEFERDQ: dump link deferd queue
+ *           - TIPC_DUMP_INPUTQ: dump link input queue
+ *           - TIPC_DUMP_WAKEUP: dump link wakeup queue
+ *           - TIPC_DUMP_ALL: dump all the link queues above
+ * @buf: returned buffer of dump data in format
+ */
+int tipc_link_dump(struct tipc_link *l, u16 dqueues, char *buf)
+{
+        int i = 0;
+        size_t sz = (dqueues) ? LINK_LMAX : LINK_LMIN;
+        struct sk_buff_head *list;
+        struct sk_buff *hskb, *tskb;
+        u32 len;
+
+        if (!l) {
+                i += scnprintf(buf, sz, "link data: (null)\n");
+                return i;
+        }
+
+        i += scnprintf(buf, sz, "link data: %x", l->addr);
+        i += scnprintf(buf + i, sz - i, " %x", l->state);
+        i += scnprintf(buf + i, sz - i, " %u", l->in_session);
+        i += scnprintf(buf + i, sz - i, " %u", l->session);
+        i += scnprintf(buf + i, sz - i, " %u", l->peer_session);
+        i += scnprintf(buf + i, sz - i, " %u", l->snd_nxt);
+        i += scnprintf(buf + i, sz - i, " %u", l->rcv_nxt);
+        i += scnprintf(buf + i, sz - i, " %u", l->snd_nxt_state);
+        i += scnprintf(buf + i, sz - i, " %u", l->rcv_nxt_state);
+        i += scnprintf(buf + i, sz - i, " %x", l->peer_caps);
+        i += scnprintf(buf + i, sz - i, " %u", l->silent_intv_cnt);
+        i += scnprintf(buf + i, sz - i, " %u", l->rst_cnt);
+        i += scnprintf(buf + i, sz - i, " %u", l->prev_from);
+        i += scnprintf(buf + i, sz - i, " %u", l->stale_cnt);
+        i += scnprintf(buf + i, sz - i, " %u", l->acked);
+
+        list = &l->transmq;
+        len = skb_queue_len(list);
+        hskb = skb_peek(list);
+        tskb = skb_peek_tail(list);
+        i += scnprintf(buf + i, sz - i, " | %u %u %u", len,
+                       (hskb) ? msg_seqno(buf_msg(hskb)) : 0,
+                       (tskb) ? msg_seqno(buf_msg(tskb)) : 0);
+
+        list = &l->deferdq;
+        len = skb_queue_len(list);
+        hskb = skb_peek(list);
+        tskb = skb_peek_tail(list);
+        i += scnprintf(buf + i, sz - i, " | %u %u %u", len,
+                       (hskb) ? msg_seqno(buf_msg(hskb)) : 0,
+                       (tskb) ? msg_seqno(buf_msg(tskb)) : 0);
+
+        list = &l->backlogq;
+        len = skb_queue_len(list);
+        hskb = skb_peek(list);
+        tskb = skb_peek_tail(list);
+        i += scnprintf(buf + i, sz - i, " | %u %u %u", len,
+                       (hskb) ? msg_seqno(buf_msg(hskb)) : 0,
+                       (tskb) ? msg_seqno(buf_msg(tskb)) : 0);
+
+        list = l->inputq;
+        len = skb_queue_len(list);
+        hskb = skb_peek(list);
+        tskb = skb_peek_tail(list);
+        i += scnprintf(buf + i, sz - i, " | %u %u %u\n", len,
+                       (hskb) ? msg_seqno(buf_msg(hskb)) : 0,
+                       (tskb) ? msg_seqno(buf_msg(tskb)) : 0);
+
+        if (dqueues & TIPC_DUMP_TRANSMQ) {
+                i += scnprintf(buf + i, sz - i, "transmq: ");
+                i += tipc_list_dump(&l->transmq, false, buf + i);
+        }
+        if (dqueues & TIPC_DUMP_BACKLOGQ) {
+                i += scnprintf(buf + i, sz - i,
+                               "backlogq: <%u %u %u %u %u>, ",
+                               l->backlog[TIPC_LOW_IMPORTANCE].len,
+                               l->backlog[TIPC_MEDIUM_IMPORTANCE].len,
+                               l->backlog[TIPC_HIGH_IMPORTANCE].len,
+                               l->backlog[TIPC_CRITICAL_IMPORTANCE].len,
+                               l->backlog[TIPC_SYSTEM_IMPORTANCE].len);
+                i += tipc_list_dump(&l->backlogq, false, buf + i);
+        }
+        if (dqueues & TIPC_DUMP_DEFERDQ) {
+                i += scnprintf(buf + i, sz - i, "deferdq: ");
+                i += tipc_list_dump(&l->deferdq, false, buf + i);
+        }
+        if (dqueues & TIPC_DUMP_INPUTQ) {
+                i += scnprintf(buf + i, sz - i, "inputq: ");
+                i += tipc_list_dump(l->inputq, false, buf + i);
+        }
+        if (dqueues & TIPC_DUMP_WAKEUP) {
+                i += scnprintf(buf + i, sz - i, "wakeup: ");
+                i += tipc_list_dump(&l->wakeupq, false, buf + i);
+        }
+
+        return i;
+}