Adding upstream version 2.6.12.upstream/2.6.12upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 761 insertions, 0 deletions

diff --git a/src/trace.c b/src/trace.c
new file mode 100644
index 0000000..9e0785c
--- /dev/null
+++ b/src/trace.c
@@ -0,0 +1,761 @@
+/*
+ * Runtime tracing API
+ *
+ * Copyright (C) 2000-2019 Willy Tarreau - w@1wt.eu
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation, version 2.1
+ * exclusively.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+ */
+
+#include <import/ist.h>
+#include <haproxy/api.h>
+#include <haproxy/buf.h>
+#include <haproxy/cli.h>
+#include <haproxy/errors.h>
+#include <haproxy/istbuf.h>
+#include <haproxy/list.h>
+#include <haproxy/log.h>
+#include <haproxy/sink.h>
+#include <haproxy/trace.h>
+
+struct list trace_sources = LIST_HEAD_INIT(trace_sources);
+THREAD_LOCAL struct buffer trace_buf = { };
+
+/* allocates the trace buffers. Returns 0 in case of failure. It is safe to
+ * call to call this function multiple times if the size changes.
+ */
+static int alloc_trace_buffers_per_thread()
+{
+	chunk_init(&trace_buf, my_realloc2(trace_buf.area, global.tune.bufsize), global.tune.bufsize);
+	return !!trace_buf.area;
+}
+
+static void free_trace_buffers_per_thread()
+{
+	chunk_destroy(&trace_buf);
+}
+
+REGISTER_PER_THREAD_ALLOC(alloc_trace_buffers_per_thread);
+REGISTER_PER_THREAD_FREE(free_trace_buffers_per_thread);
+
+/* pick the lowest non-null argument with a non-null arg_def mask */
+static inline const void *trace_pick_arg(uint32_t arg_def, const void *a1, const void *a2, const void *a3, const void *a4)
+{
+	if (arg_def & 0x0000FFFF) {
+		if ((arg_def & 0x000000FF) && a1)
+			return a1;
+		if ((arg_def & 0x0000FF00) && a2)
+			return a2;
+	}
+
+	if (arg_def & 0xFFFF0000) {
+		if ((arg_def & 0x00FF0000) && a3)
+			return a3;
+		if ((arg_def & 0xFF000000) && a4)
+			return a4;
+	}
+
+	return NULL;
+}
+
+/* Reports whether the trace is enabled for the specified arguments, needs to enable
+ * or disable tracking. It gets the same API as __trace() except for <cb> and <msg>
+ * which are not used and were dropped, and plockptr which is an optional pointer to
+ * the lockptr to be updated (or NULL) for tracking. The function returns:
+ *   0 if the trace is not enabled for the module or these values
+ *  <0 if the trace matches some locking criteria but don't have the proper level.
+ *     In this case the interested caller might have to consider disabling tracking.
+ *  >0 if the trace is enabled for the given criteria.
+ * In all cases, <plockptr> will only be set if non-null and if a locking criterion
+ * matched. It will be up to the caller to enable tracking if desired. A casual
+ * tester not interested in adjusting tracking (i.e. calling the function before
+ * deciding so prepare a buffer to be dumped) will only need to pass 0 for plockptr
+ * and check if the result is >0.
+ */
+int __trace_enabled(enum trace_level level, uint64_t mask, struct trace_source *src,
+		    const struct ist where, const char *func,
+		    const void *a1, const void *a2, const void *a3, const void *a4,
+		    const void **plockptr)
+{
+	const struct listener *li = NULL;
+	const struct proxy *fe = NULL;
+	const struct proxy *be = NULL;
+	const struct server *srv = NULL;
+	const struct session *sess = NULL;
+	const struct stream *strm = NULL;
+	const struct connection *conn = NULL;
+	const struct check *check = NULL;
+#ifdef USE_QUIC
+	const struct quic_conn *qc = NULL;
+#endif
+	const void *lockon_ptr = NULL;
+
+	if (likely(src->state == TRACE_STATE_STOPPED))
+		return 0;
+
+	/* check that at least one action is interested by this event */
+	if (((src->report_events | src->start_events | src->pause_events | src->stop_events) & mask) == 0)
+		return 0;
+
+	/* retrieve available information from the caller's arguments */
+	if (src->arg_def & TRC_ARGS_CONN)
+		conn = trace_pick_arg(src->arg_def & TRC_ARGS_CONN, a1, a2, a3, a4);
+
+	if (src->arg_def & TRC_ARGS_SESS)
+		sess = trace_pick_arg(src->arg_def & TRC_ARGS_SESS, a1, a2, a3, a4);
+
+	if (src->arg_def & TRC_ARGS_STRM)
+		strm = trace_pick_arg(src->arg_def & TRC_ARGS_STRM, a1, a2, a3, a4);
+
+	if (src->arg_def & TRC_ARGS_CHK)
+		check = trace_pick_arg(src->arg_def & TRC_ARGS_CHK, a1, a2, a3, a4);
+
+#ifdef USE_QUIC
+	if (src->arg_def & TRC_ARGS_QCON)
+		qc = trace_pick_arg(src->arg_def & TRC_ARGS_QCON, a1, a2, a3, a4);
+#endif
+
+	if (!sess && strm)
+		sess = strm->sess;
+	else if (!sess && conn && LIST_INLIST(&conn->session_list))
+		sess = conn->owner;
+	else if (!sess && check)
+		sess = check->sess;
+
+	if (sess) {
+		fe = sess->fe;
+		li = sess->listener;
+	}
+
+	if (!li && conn)
+		li = objt_listener(conn->target);
+
+	if (li && !fe)
+		fe = li->bind_conf->frontend;
+
+	if (strm) {
+		be = strm->be;
+		srv = strm->srv_conn;
+	}
+	if (check) {
+		srv = check->server;
+		be = (srv ? srv->proxy : NULL);
+	}
+
+	if (!srv && conn)
+		srv = objt_server(conn->target);
+
+	if (srv && !be)
+		be = srv->proxy;
+
+	if (!be && conn)
+		be = objt_proxy(conn->target);
+
+	/* TODO: add handling of filters here, return if no match (not even update states) */
+
+	/* check if we need to start the trace now */
+	if (src->state == TRACE_STATE_WAITING) {
+		if ((src->start_events & mask) == 0)
+			return 0;
+
+		/* TODO: add update of lockon+lockon_ptr here */
+		HA_ATOMIC_STORE(&src->state, TRACE_STATE_RUNNING);
+	}
+
+	/* we may want to lock on a particular object */
+	if (src->lockon != TRACE_LOCKON_NOTHING) {
+		switch (src->lockon) {
+		case TRACE_LOCKON_BACKEND:    lockon_ptr = be;   break;
+		case TRACE_LOCKON_CONNECTION: lockon_ptr = conn; break;
+		case TRACE_LOCKON_FRONTEND:   lockon_ptr = fe;   break;
+		case TRACE_LOCKON_LISTENER:   lockon_ptr = li;   break;
+		case TRACE_LOCKON_SERVER:     lockon_ptr = srv;  break;
+		case TRACE_LOCKON_SESSION:    lockon_ptr = sess; break;
+		case TRACE_LOCKON_STREAM:     lockon_ptr = strm; break;
+		case TRACE_LOCKON_CHECK:      lockon_ptr = check; break;
+		case TRACE_LOCKON_THREAD:     lockon_ptr = ti;   break;
+#ifdef USE_QUIC
+		case TRACE_LOCKON_QCON:       lockon_ptr = qc;   break;
+#endif
+		case TRACE_LOCKON_ARG1:       lockon_ptr = a1;   break;
+		case TRACE_LOCKON_ARG2:       lockon_ptr = a2;   break;
+		case TRACE_LOCKON_ARG3:       lockon_ptr = a3;   break;
+		case TRACE_LOCKON_ARG4:       lockon_ptr = a4;   break;
+		default: break; // silence stupid gcc -Wswitch
+		}
+
+		if (src->lockon_ptr && src->lockon_ptr != lockon_ptr)
+			return 0;
+
+		if (*plockptr && !src->lockon_ptr && lockon_ptr && src->state == TRACE_STATE_RUNNING)
+			*plockptr = lockon_ptr;
+	}
+
+	/* here the trace is running and is tracking a desired item */
+	if ((src->report_events & mask) == 0 || level > src->level) {
+		/* tracking did match, and might have to be disabled */
+		return -1;
+	}
+
+	/* OK trace still enabled */
+	return 1;
+}
+
+/* write a message for the given trace source */
+void __trace(enum trace_level level, uint64_t mask, struct trace_source *src,
+             const struct ist where, const char *func,
+             const void *a1, const void *a2, const void *a3, const void *a4,
+             void (*cb)(enum trace_level level, uint64_t mask, const struct trace_source *src,
+                        const struct ist where, const struct ist func,
+                        const void *a1, const void *a2, const void *a3, const void *a4),
+             const struct ist msg)
+{
+	const void *lockon_ptr;
+	struct ist ist_func = ist(func);
+	char tnum[4];
+	struct ist line[12];
+	int words = 0;
+	int ret;
+
+	lockon_ptr = NULL;
+	ret = __trace_enabled(level, mask, src, where, func, a1, a2, a3, a4, &lockon_ptr);
+	if (lockon_ptr)
+		HA_ATOMIC_STORE(&src->lockon_ptr, lockon_ptr);
+
+	if (ret <= 0) {
+		if (ret < 0) // may have to disable tracking
+			goto end;
+		return;
+	}
+
+	/* log the logging location truncated to 10 chars from the right so that
+	 * the line number and the end of the file name are there.
+	 */
+	line[words++] = ist("[");
+	tnum[0] = '0' + tid / 10;
+	tnum[1] = '0' + tid % 10;
+	tnum[2] = '|';
+	tnum[3] = 0;
+	line[words++] = ist(tnum);
+	line[words++] = src->name;
+	line[words++] = ist("|");
+	line[words++] = ist2("012345" + level, 1); // "0" to "5"
+	line[words++] = ist("|");
+	line[words] = where;
+	if (line[words].len > 13) {
+		line[words].ptr += (line[words].len - 13);
+		line[words].len = 13;
+	}
+	words++;
+	line[words++] = ist("] ");
+
+	if (isttest(ist_func)) {
+		line[words++] = ist_func;
+		line[words++] = ist("(): ");
+	}
+
+	if (!cb)
+		cb = src->default_cb;
+
+	if (cb && src->verbosity) {
+		/* decode function passed, we want to pre-fill the
+		 * buffer with the message and let the decode function
+		 * do its job, possibly even overwriting it.
+		 */
+		b_reset(&trace_buf);
+		b_istput(&trace_buf, msg);
+		cb(level, mask, src, where, ist_func, a1, a2, a3, a4);
+		line[words] = ist2(trace_buf.area, trace_buf.data);
+		words++;
+	}
+	else {
+		/* Note that here we could decide to print some args whose type
+		 * is known, when verbosity is above the quiet level, and even
+		 * to print the name and values of those which are declared for
+		 * lock-on.
+		 */
+		line[words++] = msg;
+	}
+
+	if (src->sink)
+		sink_write(src->sink, line, words, 0, 0, NULL);
+
+ end:
+	/* check if we need to stop the trace now */
+	if ((src->stop_events & mask) != 0) {
+		HA_ATOMIC_STORE(&src->lockon_ptr, NULL);
+		HA_ATOMIC_STORE(&src->state, TRACE_STATE_STOPPED);
+	}
+	else if ((src->pause_events & mask) != 0) {
+		HA_ATOMIC_STORE(&src->lockon_ptr, NULL);
+		HA_ATOMIC_STORE(&src->state, TRACE_STATE_WAITING);
+	}
+}
+
+/* this callback may be used when no output modification is desired */
+void trace_no_cb(enum trace_level level, uint64_t mask, const struct trace_source *src,
+		 const struct ist where, const struct ist func,
+		 const void *a1, const void *a2, const void *a3, const void *a4)
+{
+	/* do nothing */
+}
+
+/* registers trace source <source>. Modifies the list element!
+ * The {start,pause,stop,report} events are not changed so the source may
+ * preset them.
+ */
+void trace_register_source(struct trace_source *source)
+{
+	source->lockon = TRACE_LOCKON_NOTHING;
+	source->level = TRACE_LEVEL_USER;
+	source->verbosity = 1;
+	source->sink = NULL;
+	source->state = TRACE_STATE_STOPPED;
+	source->lockon_ptr = NULL;
+	LIST_APPEND(&trace_sources, &source->source_link);
+}
+
+struct trace_source *trace_find_source(const char *name)
+{
+	struct trace_source *src;
+	const struct ist iname = ist(name);
+
+	list_for_each_entry(src, &trace_sources, source_link)
+		if (isteq(src->name, iname))
+			return src;
+	return NULL;
+}
+
+const struct trace_event *trace_find_event(const struct trace_event *ev, const char *name)
+{
+	for (; ev && ev->mask; ev++)
+		if (strcmp(ev->name, name) == 0)
+			return ev;
+	return NULL;
+}
+
+/* parse the command, returns 1 if a message is returned, otherwise zero */
+static int cli_parse_trace(char **args, char *payload, struct appctx *appctx, void *private)
+{
+	struct trace_source *src;
+	uint64_t *ev_ptr = NULL;
+
+	if (!cli_has_level(appctx, ACCESS_LVL_OPER))
+		return 1;
+
+	if (!*args[1]) {
+		/* no arg => report the list of supported sources as a warning */
+		chunk_printf(&trash,
+			     "Supported trace sources and states (.=stopped, w=waiting, R=running) :\n"
+			     " [.] 0          : not a source, will immediately stop all traces\n"
+			     );
+
+		list_for_each_entry(src, &trace_sources, source_link)
+			chunk_appendf(&trash, " [%c] %-10s : %s\n", trace_state_char(src->state), src->name.ptr, src->desc);
+
+		trash.area[trash.data] = 0;
+		return cli_msg(appctx, LOG_WARNING, trash.area);
+	}
+
+	if (strcmp(args[1], "0") == 0) {
+		/* emergency stop of all traces */
+		list_for_each_entry(src, &trace_sources, source_link)
+			HA_ATOMIC_STORE(&src->state, TRACE_STATE_STOPPED);
+		return cli_msg(appctx, LOG_NOTICE, "All traces now stopped");
+	}
+
+	src = trace_find_source(args[1]);
+	if (!src)
+		return cli_err(appctx, "No such trace source");
+
+	if (!*args[2]) {
+		return cli_msg(appctx, LOG_WARNING,
+			       "Supported commands:\n"
+			       "  event     : list/enable/disable source-specific event reporting\n"
+			       //"  filter    : list/enable/disable generic filters\n"
+			       "  level     : list/set trace reporting level\n"
+			       "  lock      : automatic lock on thread/connection/stream/...\n"
+			       "  pause     : pause and automatically restart after a specific event\n"
+			       "  sink      : list/set event sinks\n"
+			       "  start     : start immediately or after a specific event\n"
+			       "  stop      : stop immediately or after a specific event\n"
+			       "  verbosity : list/set trace output verbosity\n"
+			       );
+	}
+	else if ((strcmp(args[2], "event") == 0 && (ev_ptr = &src->report_events)) ||
+	         (strcmp(args[2], "pause") == 0 && (ev_ptr = &src->pause_events)) ||
+	         (strcmp(args[2], "start") == 0 && (ev_ptr = &src->start_events)) ||
+	         (strcmp(args[2], "stop")  == 0 && (ev_ptr = &src->stop_events))) {
+		const struct trace_event *ev;
+		const char *name = args[3];
+		int neg = 0;
+		int i;
+
+		/* skip prefix '!', '-', '+' and remind negation */
+		while (*name) {
+			if (*name == '!' || *name == '-')
+				neg = 1;
+			else if (*name == '+')
+				neg = 0;
+			else
+				break;
+			name++;
+		}
+
+		if (!*name) {
+			chunk_printf(&trash, "Supported events for source %s (+=enabled, -=disabled):\n", src->name.ptr);
+			if (ev_ptr != &src->report_events)
+				chunk_appendf(&trash, "  - now          : don't wait for events, immediately change the state\n");
+			chunk_appendf(&trash, "  - none         : disable all event types\n");
+			chunk_appendf(&trash, "  - any          : enable all event types\n");
+			for (i = 0; src->known_events && src->known_events[i].mask; i++) {
+				chunk_appendf(&trash, "  %c %-12s : %s\n",
+					      trace_event_char(*ev_ptr, src->known_events[i].mask),
+					      src->known_events[i].name, src->known_events[i].desc);
+			}
+			trash.area[trash.data] = 0;
+			return cli_msg(appctx, LOG_WARNING, trash.area);
+		}
+
+		if (strcmp(name, "now") == 0 && ev_ptr != &src->report_events) {
+			HA_ATOMIC_STORE(ev_ptr, 0);
+			if (ev_ptr == &src->pause_events) {
+				HA_ATOMIC_STORE(&src->lockon_ptr, NULL);
+				HA_ATOMIC_STORE(&src->state, TRACE_STATE_WAITING);
+			}
+			else if (ev_ptr == &src->start_events) {
+				HA_ATOMIC_STORE(&src->state, TRACE_STATE_RUNNING);
+			}
+			else if (ev_ptr == &src->stop_events) {
+				HA_ATOMIC_STORE(&src->lockon_ptr, NULL);
+				HA_ATOMIC_STORE(&src->state, TRACE_STATE_STOPPED);
+			}
+			return 0;
+		}
+
+		if (strcmp(name, "none") == 0)
+			HA_ATOMIC_STORE(ev_ptr, 0);
+		else if (strcmp(name, "any") == 0)
+			HA_ATOMIC_STORE(ev_ptr, ~0);
+		else {
+			ev = trace_find_event(src->known_events, name);
+			if (!ev)
+				return cli_err(appctx, "No such trace event");
+
+			if (!neg)
+				HA_ATOMIC_OR(ev_ptr, ev->mask);
+			else
+				HA_ATOMIC_AND(ev_ptr, ~ev->mask);
+		}
+	}
+	else if (strcmp(args[2], "sink") == 0) {
+		const char *name = args[3];
+		struct sink *sink;
+
+		if (!*name) {
+			chunk_printf(&trash, "Supported sinks for source %s (*=current):\n", src->name.ptr);
+			chunk_appendf(&trash, "  %c none       : no sink\n", src->sink ? ' ' : '*');
+			list_for_each_entry(sink, &sink_list, sink_list) {
+				chunk_appendf(&trash, "  %c %-10s : %s\n",
+					      src->sink == sink ? '*' : ' ',
+					      sink->name, sink->desc);
+			}
+			trash.area[trash.data] = 0;
+			return cli_msg(appctx, LOG_WARNING, trash.area);
+		}
+
+		if (strcmp(name, "none") == 0)
+			sink = NULL;
+		else {
+			sink = sink_find(name);
+			if (!sink)
+				return cli_err(appctx, "No such sink");
+		}
+
+		HA_ATOMIC_STORE(&src->sink, sink);
+	}
+	else if (strcmp(args[2], "level") == 0) {
+		const char *name = args[3];
+
+		if (!*name) {
+			chunk_printf(&trash, "Supported trace levels for source %s:\n", src->name.ptr);
+			chunk_appendf(&trash, "  %c error      : report errors\n",
+				      src->level == TRACE_LEVEL_ERROR ? '*' : ' ');
+			chunk_appendf(&trash, "  %c user       : also information useful to the end user\n",
+				      src->level == TRACE_LEVEL_USER ? '*' : ' ');
+			chunk_appendf(&trash, "  %c proto      : also protocol-level updates\n",
+				      src->level == TRACE_LEVEL_PROTO ? '*' : ' ');
+			chunk_appendf(&trash, "  %c state      : also report internal state changes\n",
+				      src->level == TRACE_LEVEL_STATE ? '*' : ' ');
+			chunk_appendf(&trash, "  %c data       : also report data transfers\n",
+				      src->level == TRACE_LEVEL_DATA ? '*' : ' ');
+			chunk_appendf(&trash, "  %c developer  : also report information useful only to the developer\n",
+				      src->level == TRACE_LEVEL_DEVELOPER ? '*' : ' ');
+			trash.area[trash.data] = 0;
+			return cli_msg(appctx, LOG_WARNING, trash.area);
+		}
+
+		if (strcmp(name, "error") == 0)
+			HA_ATOMIC_STORE(&src->level, TRACE_LEVEL_ERROR);
+		else if (strcmp(name, "user") == 0)
+			HA_ATOMIC_STORE(&src->level, TRACE_LEVEL_USER);
+		else if (strcmp(name, "proto") == 0)
+			HA_ATOMIC_STORE(&src->level, TRACE_LEVEL_PROTO);
+		else if (strcmp(name, "state") == 0)
+			HA_ATOMIC_STORE(&src->level, TRACE_LEVEL_STATE);
+		else if (strcmp(name, "data") == 0)
+			HA_ATOMIC_STORE(&src->level, TRACE_LEVEL_DATA);
+		else if (strcmp(name, "developer") == 0)
+			HA_ATOMIC_STORE(&src->level, TRACE_LEVEL_DEVELOPER);
+		else
+			return cli_err(appctx, "No such trace level");
+	}
+	else if (strcmp(args[2], "lock") == 0) {
+		const char *name = args[3];
+
+		if (!*name) {
+			chunk_printf(&trash, "Supported lock-on criteria for source %s:\n", src->name.ptr);
+			if (src->arg_def & (TRC_ARGS_CONN|TRC_ARGS_STRM))
+				chunk_appendf(&trash, "  %c backend    : lock on the backend that started the trace\n",
+				              src->lockon == TRACE_LOCKON_BACKEND ? '*' : ' ');
+
+			if (src->arg_def & TRC_ARGS_CHK)
+				chunk_appendf(&trash, "  %c check      : lock on the check that started the trace\n",
+				              src->lockon == TRACE_LOCKON_CHECK ? '*' : ' ');
+
+			if (src->arg_def & TRC_ARGS_CONN)
+				chunk_appendf(&trash, "  %c connection : lock on the connection that started the trace\n",
+				              src->lockon == TRACE_LOCKON_CONNECTION ? '*' : ' ');
+
+			if (src->arg_def & (TRC_ARGS_CONN|TRC_ARGS_SESS|TRC_ARGS_STRM))
+				chunk_appendf(&trash, "  %c frontend   : lock on the frontend that started the trace\n",
+				              src->lockon == TRACE_LOCKON_FRONTEND ? '*' : ' ');
+
+			if (src->arg_def & (TRC_ARGS_CONN|TRC_ARGS_SESS|TRC_ARGS_STRM))
+				chunk_appendf(&trash, "  %c listener   : lock on the listener that started the trace\n",
+				              src->lockon == TRACE_LOCKON_LISTENER ? '*' : ' ');
+
+			chunk_appendf(&trash, "  %c nothing    : do not lock on anything\n",
+				      src->lockon == TRACE_LOCKON_NOTHING ? '*' : ' ');
+
+			if (src->arg_def & (TRC_ARGS_CONN|TRC_ARGS_STRM))
+				chunk_appendf(&trash, "  %c server     : lock on the server that started the trace\n",
+				              src->lockon == TRACE_LOCKON_SERVER ? '*' : ' ');
+
+			if (src->arg_def & (TRC_ARGS_CONN|TRC_ARGS_SESS|TRC_ARGS_STRM))
+				chunk_appendf(&trash, "  %c session    : lock on the session that started the trace\n",
+				              src->lockon == TRACE_LOCKON_SESSION ? '*' : ' ');
+
+			if (src->arg_def & TRC_ARGS_STRM)
+				chunk_appendf(&trash, "  %c stream     : lock on the stream that started the trace\n",
+				              src->lockon == TRACE_LOCKON_STREAM ? '*' : ' ');
+
+			chunk_appendf(&trash, "  %c thread     : lock on the thread that started the trace\n",
+				      src->lockon == TRACE_LOCKON_THREAD ? '*' : ' ');
+
+			if (src->lockon_args && src->lockon_args[0].name)
+				chunk_appendf(&trash, "  %c %-10s : %s\n",
+				              src->lockon == TRACE_LOCKON_ARG1 ? '*' : ' ',
+				              src->lockon_args[0].name, src->lockon_args[0].desc);
+
+			if (src->lockon_args && src->lockon_args[1].name)
+				chunk_appendf(&trash, "  %c %-10s : %s\n",
+				              src->lockon == TRACE_LOCKON_ARG2 ? '*' : ' ',
+				              src->lockon_args[1].name, src->lockon_args[1].desc);
+
+			if (src->lockon_args && src->lockon_args[2].name)
+				chunk_appendf(&trash, "  %c %-10s : %s\n",
+				              src->lockon == TRACE_LOCKON_ARG3 ? '*' : ' ',
+				              src->lockon_args[2].name, src->lockon_args[2].desc);
+
+			if (src->lockon_args && src->lockon_args[3].name)
+				chunk_appendf(&trash, "  %c %-10s : %s\n",
+				              src->lockon == TRACE_LOCKON_ARG4 ? '*' : ' ',
+				              src->lockon_args[3].name, src->lockon_args[3].desc);
+
+			trash.area[trash.data] = 0;
+			return cli_msg(appctx, LOG_WARNING, trash.area);
+		}
+		else if ((src->arg_def & (TRC_ARGS_CONN|TRC_ARGS_STRM)) && strcmp(name, "backend") == 0) {
+			HA_ATOMIC_STORE(&src->lockon, TRACE_LOCKON_BACKEND);
+			HA_ATOMIC_STORE(&src->lockon_ptr, NULL);
+		}
+		else if ((src->arg_def & TRC_ARGS_CHK) && strcmp(name, "check") == 0) {
+			HA_ATOMIC_STORE(&src->lockon, TRACE_LOCKON_CHECK);
+			HA_ATOMIC_STORE(&src->lockon_ptr, NULL);
+		}
+		else if ((src->arg_def & TRC_ARGS_CONN) && strcmp(name, "connection") == 0) {
+			HA_ATOMIC_STORE(&src->lockon, TRACE_LOCKON_CONNECTION);
+			HA_ATOMIC_STORE(&src->lockon_ptr, NULL);
+		}
+		else if ((src->arg_def & (TRC_ARGS_CONN|TRC_ARGS_SESS|TRC_ARGS_STRM)) && strcmp(name, "frontend") == 0) {
+			HA_ATOMIC_STORE(&src->lockon, TRACE_LOCKON_FRONTEND);
+			HA_ATOMIC_STORE(&src->lockon_ptr, NULL);
+		}
+		else if ((src->arg_def & (TRC_ARGS_CONN|TRC_ARGS_SESS|TRC_ARGS_STRM)) && strcmp(name, "listener") == 0) {
+			HA_ATOMIC_STORE(&src->lockon, TRACE_LOCKON_LISTENER);
+			HA_ATOMIC_STORE(&src->lockon_ptr, NULL);
+		}
+		else if (strcmp(name, "nothing") == 0) {
+			HA_ATOMIC_STORE(&src->lockon, TRACE_LOCKON_NOTHING);
+			HA_ATOMIC_STORE(&src->lockon_ptr, NULL);
+		}
+		else if ((src->arg_def & (TRC_ARGS_CONN|TRC_ARGS_STRM)) && strcmp(name, "server") == 0) {
+			HA_ATOMIC_STORE(&src->lockon, TRACE_LOCKON_SERVER);
+			HA_ATOMIC_STORE(&src->lockon_ptr, NULL);
+		}
+		else if ((src->arg_def & (TRC_ARGS_CONN|TRC_ARGS_SESS|TRC_ARGS_STRM)) && strcmp(name, "session") == 0) {
+			HA_ATOMIC_STORE(&src->lockon, TRACE_LOCKON_SESSION);
+			HA_ATOMIC_STORE(&src->lockon_ptr, NULL);
+		}
+		else if ((src->arg_def & TRC_ARGS_STRM) && strcmp(name, "stream") == 0) {
+			HA_ATOMIC_STORE(&src->lockon, TRACE_LOCKON_STREAM);
+			HA_ATOMIC_STORE(&src->lockon_ptr, NULL);
+		}
+		else if (strcmp(name, "thread") == 0) {
+			HA_ATOMIC_STORE(&src->lockon, TRACE_LOCKON_THREAD);
+			HA_ATOMIC_STORE(&src->lockon_ptr, NULL);
+		}
+		else if (src->lockon_args && src->lockon_args[0].name && strcmp(name, src->lockon_args[0].name) == 0) {
+			HA_ATOMIC_STORE(&src->lockon, TRACE_LOCKON_ARG1);
+			HA_ATOMIC_STORE(&src->lockon_ptr, NULL);
+		}
+		else if (src->lockon_args && src->lockon_args[1].name && strcmp(name, src->lockon_args[1].name) == 0) {
+			HA_ATOMIC_STORE(&src->lockon, TRACE_LOCKON_ARG2);
+			HA_ATOMIC_STORE(&src->lockon_ptr, NULL);
+		}
+		else if (src->lockon_args && src->lockon_args[2].name && strcmp(name, src->lockon_args[2].name) == 0) {
+			HA_ATOMIC_STORE(&src->lockon, TRACE_LOCKON_ARG3);
+			HA_ATOMIC_STORE(&src->lockon_ptr, NULL);
+		}
+		else if (src->lockon_args && src->lockon_args[3].name && strcmp(name, src->lockon_args[3].name) == 0) {
+			HA_ATOMIC_STORE(&src->lockon, TRACE_LOCKON_ARG4);
+			HA_ATOMIC_STORE(&src->lockon_ptr, NULL);
+		}
+		else
+			return cli_err(appctx, "Unsupported lock-on criterion");
+	}
+	else if (strcmp(args[2], "verbosity") == 0) {
+		const char *name = args[3];
+		const struct name_desc *nd;
+
+		if (!*name) {
+			chunk_printf(&trash, "Supported trace verbosities for source %s:\n", src->name.ptr);
+			chunk_appendf(&trash, "  %c quiet      : only report basic information with no decoding\n",
+				      src->verbosity == 0 ? '*' : ' ');
+			if (!src->decoding || !src->decoding[0].name) {
+				chunk_appendf(&trash, "  %c default    : report extra information when available\n",
+					      src->verbosity > 0 ? '*' : ' ');
+			} else {
+				for (nd = src->decoding; nd->name && nd->desc; nd++)
+					chunk_appendf(&trash, "  %c %-10s : %s\n",
+					              nd == (src->decoding + src->verbosity - 1) ? '*' : ' ',
+						      nd->name, nd->desc);
+			}
+			trash.area[trash.data] = 0;
+			return cli_msg(appctx, LOG_WARNING, trash.area);
+		}
+
+		if (strcmp(name, "quiet") == 0)
+			HA_ATOMIC_STORE(&src->verbosity, 0);
+		else if (!src->decoding || !src->decoding[0].name) {
+			if (strcmp(name, "default") == 0)
+				HA_ATOMIC_STORE(&src->verbosity, 1);
+			else
+				return cli_err(appctx, "No such verbosity level");
+		} else {
+			for (nd = src->decoding; nd->name && nd->desc; nd++)
+				if (strcmp(name, nd->name) == 0)
+					break;
+
+			if (!nd->name || !nd->desc)
+				return cli_err(appctx, "No such verbosity level");
+
+			HA_ATOMIC_STORE(&src->verbosity, (nd - src->decoding) + 1);
+		}
+	}
+	else
+		return cli_err(appctx, "Unknown trace keyword");
+
+	return 0;
+}
+
+/* parse the command, returns 1 if a message is returned, otherwise zero */
+static int cli_parse_show_trace(char **args, char *payload, struct appctx *appctx, void *private)
+{
+	struct trace_source *src;
+	const struct sink *sink;
+	int i;
+
+	args++; // make args[1] the 1st arg
+
+	if (!*args[1]) {
+		/* no arg => report the list of supported sources */
+		chunk_printf(&trash,
+			     "Supported trace sources and states (.=stopped, w=waiting, R=running) :\n"
+			     );
+
+		list_for_each_entry(src, &trace_sources, source_link) {
+			sink = src->sink;
+			chunk_appendf(&trash, " [%c] %-10s -> %s [drp %u]  [%s]\n",
+				      trace_state_char(src->state), src->name.ptr,
+				      sink ? sink->name : "none",
+				      sink ? sink->ctx.dropped : 0,
+				      src->desc);
+		}
+
+		trash.area[trash.data] = 0;
+		return cli_msg(appctx, LOG_INFO, trash.area);
+	}
+
+	if (!cli_has_level(appctx, ACCESS_LVL_OPER))
+		return 1;
+
+	src = trace_find_source(args[1]);
+	if (!src)
+		return cli_err(appctx, "No such trace source");
+
+	sink = src->sink;
+	chunk_printf(&trash, "Trace status for %s:\n", src->name.ptr);
+	chunk_appendf(&trash, "  - sink: %s [%u dropped]\n",
+		      sink ? sink->name : "none", sink ? sink->ctx.dropped : 0);
+
+	chunk_appendf(&trash, "  - event name   :     report    start    stop    pause\n");
+	for (i = 0; src->known_events && src->known_events[i].mask; i++) {
+		chunk_appendf(&trash, "    %-12s :        %c        %c        %c       %c\n",
+			      src->known_events[i].name,
+			      trace_event_char(src->report_events, src->known_events[i].mask),
+			      trace_event_char(src->start_events, src->known_events[i].mask),
+			      trace_event_char(src->stop_events, src->known_events[i].mask),
+			      trace_event_char(src->pause_events, src->known_events[i].mask));
+	}
+
+	trash.area[trash.data] = 0;
+	return cli_msg(appctx, LOG_WARNING, trash.area);
+}
+
+static struct cli_kw_list cli_kws = {{ },{
+	{ { "trace", NULL },         "trace [<module>|0] [cmd [args...]]      : manage live tracing (empty to list, 0 to stop all)", cli_parse_trace, NULL, NULL },
+	{ { "show", "trace", NULL }, "show trace [<module>]                   : show live tracing state",                            cli_parse_show_trace, NULL, NULL },
+	{{},}
+}};
+
+INITCALL1(STG_REGISTER, cli_register_kw, &cli_kws);
+
+/*
+ * Local variables:
+ *  c-indent-level: 8
+ *  c-basic-offset: 8
+ * End:
+ */