[PATCH v4 00/10] cxl: add monitor support for trace events

[PATCH v4 00/10] cxl: add monitor support for trace events

[Dave Jiang]

This patch series for ndctl implements the monitor command for the cxl tool.
The initial implementation will collect CXL trace events emitted by the
kernel. libtraceevent and libtracefs will be used to parse the trace
event buffer. The monitor will pend on an epoll fd and wait for new event
entries to be posted. The output will be in json format. By default the events
are emitted to stdio, but can also be logged to a file. Each event is converted
to a JSON object and logged as such. All the fields exported are read by the
monitor code and added to the JSON object.

v4:
- Fix num_to_json for less than int size (Ira)
- Use TEP_FIELD flags to determine data type. (Steve)
- Use tracefs_event_enable() instad of directly toggle sysfs via lib calls (Steve)
- Remove tracefs_trace_is_on() in disable() call (Steve)
- Update to use tep_data_pid() (Steve)

v3:
- Change uuid parsing from u8[] to uuid_t (Alison)
- Add event_name to event_ctx for filtering (Alison)
- Add event_pid to event_ctx for filtering (Alison)
- Add parse_event callback to event_ctx for filtering (Alison)

v2:
- Simplify logging functions (Nathan)
- Drop ndctl prefix (Vishal)
- Reduce to single trace event system (Alison)
- Add systemd startup file
- Add man page

---

Alison Schofield (1):
      cxl: add an optional pid check to event parsing

Dave Jiang (9):
      cxl: add helper function to parse trace event to json object
      cxl: add helper to parse through all current events
      cxl: add common function to enable event trace
      cxl: add common function to disable event trace
      cxl: add monitor function for event trace events
      cxl: add logging functions for monitor
      cxl: add monitor command to cxl
      cxl: add systemd service for monitor
      cxl: add man page documentation for monitor


 Documentation/cxl/cxl-monitor.txt |  77 +++++++++
 cxl/builtin.h                     |   1 +
 cxl/cxl-monitor.service           |   9 +
 cxl/cxl.c                         |   1 +
 cxl/event_trace.c                 | 263 ++++++++++++++++++++++++++++++
 cxl/event_trace.h                 |  28 ++++
 cxl/meson.build                   |   8 +
 cxl/monitor.c                     | 240 +++++++++++++++++++++++++++
 meson.build                       |   3 +
 ndctl.spec.in                     |   1 +
 10 files changed, 631 insertions(+)
 create mode 100644 Documentation/cxl/cxl-monitor.txt
 create mode 100644 cxl/cxl-monitor.service
 create mode 100644 cxl/event_trace.c
 create mode 100644 cxl/event_trace.h
 create mode 100644 cxl/monitor.c

--

[PATCH v4 01/10] cxl: add helper function to parse trace event to json object

[Dave Jiang]

Add the helper function that parses a trace event captured by
libtraceevent in a tep handle. All the parsed fields are added to a json
object. The json object is added to the provided list in the input parameter.

Tested-by: Alison Schofield <alison.schofield@intel.com>
Signed-off-by: Dave Jiang <dave.jiang@intel.com>
---
 cxl/event_trace.c |  201 +++++++++++++++++++++++++++++++++++++++++++++++++++++
 cxl/event_trace.h |   14 ++++
 cxl/meson.build   |    2 +
 meson.build       |    1 
 4 files changed, 218 insertions(+)
 create mode 100644 cxl/event_trace.c
 create mode 100644 cxl/event_trace.h

diff --git a/cxl/event_trace.c b/cxl/event_trace.c
new file mode 100644
index 000000000000..1b1b037e48bf
--- /dev/null
+++ b/cxl/event_trace.c
@@ -0,0 +1,201 @@
+// SPDX-License-Identifier: GPL-2.0
+// Copyright (C) 2022, Intel Corp. All rights reserved.
+#include <stdio.h>
+#include <json-c/json.h>
+#include <util/json.h>
+#include <util/util.h>
+#include <util/parse-options.h>
+#include <util/parse-configs.h>
+#include <util/strbuf.h>
+#include <util/sysfs.h>
+#include <ccan/list/list.h>
+#include <ndctl/ndctl.h>
+#include <ndctl/libndctl.h>
+#include <sys/epoll.h>
+#include <sys/stat.h>
+#include <libcxl.h>
+#include <uuid/uuid.h>
+#include <traceevent/event-parse.h>
+#include "json.h"
+#include "event_trace.h"
+
+#define _GNU_SOURCE
+#include <string.h>
+
+static struct json_object *num_to_json(void *num, int elem_size, unsigned long flags)
+{
+	bool sign = flags & TEP_FIELD_IS_SIGNED;
+	int64_t val = 0;
+
+	/* special case 64 bit as the call depends on sign */
+	if (elem_size == 8) {
+		if (sign)
+			return json_object_new_int64(*(int64_t *)num);
+		else
+			return json_object_new_uint64(*(uint64_t *)num);
+	}
+
+	/* All others fit in a signed 64 bit */
+	switch (elem_size) {
+	case 1:
+		if (sign)
+			val = *(int8_t *)num;
+		else
+			val = *(uint8_t *)num;
+		break;
+	case 2:
+		if (sign)
+			val = *(int16_t *)num;
+		else
+			val = *(uint16_t *)num;
+		break;
+	case 4:
+		if (sign)
+			val = *(int32_t *)num;
+		else
+			val = *(uint32_t *)num;
+		break;
+	default:
+		/*
+		 * Odd sizes are converted in the kernel to one of the above.
+		 * It is an error to see them here.
+		 */
+		return NULL;
+	}
+
+	return json_object_new_int64(val);
+}
+
+static int cxl_event_to_json_callback(struct tep_event *event,
+		struct tep_record *record, struct list_head *jlist_head)
+{
+	struct tep_format_field **fields;
+	struct json_object *jevent, *jobj, *jarray;
+	struct jlist_node *jnode;
+	int i, j, rc = 0;
+
+	jnode = malloc(sizeof(*jnode));
+	if (!jnode)
+		return -ENOMEM;
+
+	jevent = json_object_new_object();
+	if (!jevent) {
+		rc = -ENOMEM;
+		goto err_jevent;
+	}
+	jnode->jobj = jevent;
+
+	fields = tep_event_fields(event);
+	if (!fields) {
+		rc = -ENOENT;
+		goto err;
+	}
+
+	jobj = json_object_new_string(event->system);
+	if (!jobj) {
+		rc = -ENOMEM;
+		goto err;
+	}
+	json_object_object_add(jevent, "system", jobj);
+
+	jobj = json_object_new_string(event->name);
+	if (!jobj) {
+		rc = -ENOMEM;
+		goto err;
+	}
+	json_object_object_add(jevent, "event", jobj);
+
+	jobj = json_object_new_uint64(record->ts);
+	if (!jobj) {
+		rc = -ENOMEM;
+		goto err;
+	}
+	json_object_object_add(jevent, "timestamp", jobj);
+
+	for (i = 0; fields[i]; i++) {
+		struct tep_format_field *f = fields[i];
+		int len;
+
+		if (f->flags & TEP_FIELD_IS_STRING) {
+			char *str;
+
+			str = tep_get_field_raw(NULL, event, f->name, record, &len, 0);
+			if (!str)
+				continue;
+
+			jobj = json_object_new_string(str);
+			if (!jobj) {
+				rc = -ENOMEM;
+				goto err;
+			}
+
+			json_object_object_add(jevent, f->name, jobj);
+		} else if (f->flags & TEP_FIELD_IS_ARRAY) {
+			unsigned char *data;
+			int chunks;
+
+			data = tep_get_field_raw(NULL, event, f->name, record, &len, 0);
+			if (!data)
+				continue;
+
+			jarray = json_object_new_array();
+			if (!jarray) {
+				rc = -ENOMEM;
+				goto err;
+			}
+
+			chunks = f->size / f->elementsize;
+			for (j = 0; j < chunks; j++) {
+				jobj = num_to_json(data, f->elementsize, f->flags);
+				if (!jobj) {
+					json_object_put(jarray);
+					return -ENOMEM;
+				}
+				json_object_array_add(jarray, jobj);
+				data += f->elementsize;
+			}
+
+			json_object_object_add(jevent, f->name, jarray);
+		} else { /* single number */
+			unsigned char *data;
+			char *tmp;
+
+			data = tep_get_field_raw(NULL, event, f->name, record, &len, 0);
+			if (!data)
+				continue;
+
+			/* check to see if we have a UUID */
+			tmp = strcasestr(f->type, "uuid_t");
+			if (tmp) {
+				char uuid[SYSFS_ATTR_SIZE];
+
+				uuid_unparse(data, uuid);
+				jobj = json_object_new_string(uuid);
+				if (!jobj) {
+					rc = -ENOMEM;
+					goto err;
+				}
+
+				json_object_object_add(jevent, f->name, jobj);
+				continue;
+			}
+
+			jobj = num_to_json(data, f->elementsize, f->flags);
+			if (!jobj) {
+				rc = -ENOMEM;
+				goto err;
+			}
+
+			json_object_object_add(jevent, f->name, jobj);
+		}
+	}
+
+	list_add_tail(jlist_head, &jnode->list);
+	return 0;
+
+err:
+	json_object_put(jevent);
+err_jevent:
+	free(jnode);
+	return rc;
+}
diff --git a/cxl/event_trace.h b/cxl/event_trace.h
new file mode 100644
index 000000000000..00975a0b5680
--- /dev/null
+++ b/cxl/event_trace.h
@@ -0,0 +1,14 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/* Copyright (C) 2022 Intel Corporation. All rights reserved. */
+#ifndef __CXL_EVENT_TRACE_H__
+#define __CXL_EVENT_TRACE_H__
+
+#include <json-c/json.h>
+#include <ccan/list/list.h>
+
+struct jlist_node {
+	struct json_object *jobj;
+	struct list_node list;
+};
+
+#endif
diff --git a/cxl/meson.build b/cxl/meson.build
index f2474aaa6e2e..8c7733431613 100644
--- a/cxl/meson.build
+++ b/cxl/meson.build
@@ -7,6 +7,7 @@ cxl_src = [
   'memdev.c',
   'json.c',
   'filter.c',
+  'event_trace.c',
 ]
 
 cxl_tool = executable('cxl',
@@ -19,6 +20,7 @@ cxl_tool = executable('cxl',
     kmod,
     json,
     versiondep,
+    traceevent,
   ],
   install : true,
   install_dir : rootbindir,
diff --git a/meson.build b/meson.build
index 20a646d135c7..f611e0bdd7f3 100644
--- a/meson.build
+++ b/meson.build
@@ -142,6 +142,7 @@ kmod = dependency('libkmod')
 libudev = dependency('libudev')
 uuid = dependency('uuid')
 json = dependency('json-c')
+traceevent = dependency('libtraceevent')
 if get_option('docs').enabled()
   if get_option('asciidoctor').enabled()
     asciidoc = find_program('asciidoctor', required : true)

[PATCH v4 02/10] cxl: add helper to parse through all current events

[Dave Jiang]

Add common function to iterate through and extract the events in the
current trace buffer. The function uses tracefs_iterate_raw_events() from
libtracefs to go through all the events loaded into a tep_handle. A
callback is provided to the API call in order to parse the event. For cxl
monitor, an array of interested "systems" is provided in order to filter
for the interested events.

Tested-by: Alison Schofield <alison.schofield@intel.com>
Signed-off-by: Dave Jiang <dave.jiang@intel.com>
---
 cxl/event_trace.c |   36 ++++++++++++++++++++++++++++++++++++
 cxl/event_trace.h |   10 ++++++++++
 cxl/meson.build   |    1 +
 meson.build       |    2 ++
 4 files changed, 49 insertions(+)

diff --git a/cxl/event_trace.c b/cxl/event_trace.c
index 1b1b037e48bf..4667044e4a66 100644
--- a/cxl/event_trace.c
+++ b/cxl/event_trace.c
@@ -16,6 +16,7 @@
 #include <libcxl.h>
 #include <uuid/uuid.h>
 #include <traceevent/event-parse.h>
+#include <tracefs/tracefs.h>
 #include "json.h"
 #include "event_trace.h"
 
@@ -199,3 +200,38 @@ err_jevent:
 	free(jnode);
 	return rc;
 }
+
+static int cxl_event_parse_cb(struct tep_event *event, struct tep_record *record,
+		int cpu, void *ctx)
+{
+	struct event_ctx *event_ctx = (struct event_ctx *)ctx;
+
+	/* Filter out all the events that the caller isn't interested in. */
+	if (strcmp(event->system, event_ctx->system) != 0)
+		return 0;
+
+	if (event_ctx->event_name) {
+		if (strcmp(event->name, event_ctx->event_name) != 0)
+			return 0;
+	}
+
+	if (event_ctx->parse_event)
+		return event_ctx->parse_event(event, record, &event_ctx->jlist_head);
+
+	return cxl_event_to_json_callback(event, record, &event_ctx->jlist_head);
+}
+
+int cxl_parse_events(struct tracefs_instance *inst, struct event_ctx *ectx)
+{
+	struct tep_handle *tep;
+	int rc;
+
+	tep = tracefs_local_events(NULL);
+	if (!tep)
+		return -ENOMEM;
+
+	rc = tracefs_iterate_raw_events(tep, inst, NULL, 0,
+			cxl_event_parse_cb, ectx);
+	tep_free(tep);
+	return rc;
+}
diff --git a/cxl/event_trace.h b/cxl/event_trace.h
index 00975a0b5680..582882c1eb35 100644
--- a/cxl/event_trace.h
+++ b/cxl/event_trace.h
@@ -11,4 +11,14 @@ struct jlist_node {
 	struct list_node list;
 };
 
+struct event_ctx {
+	const char *system;
+	struct list_head jlist_head;
+	const char *event_name;					/* optional */
+	int (*parse_event)(struct tep_event *event, struct tep_record *record,
+			   struct list_head *jlist_head);	/* optional */
+};
+
+int cxl_parse_events(struct tracefs_instance *inst, struct event_ctx *ectx);
+
 #endif
diff --git a/cxl/meson.build b/cxl/meson.build
index 8c7733431613..c59876262e76 100644
--- a/cxl/meson.build
+++ b/cxl/meson.build
@@ -21,6 +21,7 @@ cxl_tool = executable('cxl',
     json,
     versiondep,
     traceevent,
+    tracefs,
   ],
   install : true,
   install_dir : rootbindir,
diff --git a/meson.build b/meson.build
index f611e0bdd7f3..c204c8ac52de 100644
--- a/meson.build
+++ b/meson.build
@@ -143,6 +143,8 @@ libudev = dependency('libudev')
 uuid = dependency('uuid')
 json = dependency('json-c')
 traceevent = dependency('libtraceevent')
+tracefs = dependency('libtracefs')
+
 if get_option('docs').enabled()
   if get_option('asciidoctor').enabled()
     asciidoc = find_program('asciidoctor', required : true)

[PATCH v4 03/10] cxl: add common function to enable event trace

[Dave Jiang]

Add a common function for cxl command to enable event tracing for the
instance created. The interested "systems" will be enabled for tracing
as well.

Signed-off-by: Dave Jiang <dave.jiang@intel.com>
---
 cxl/event_trace.c |   16 ++++++++++++++++
 cxl/event_trace.h |    2 ++
 2 files changed, 18 insertions(+)

diff --git a/cxl/event_trace.c b/cxl/event_trace.c
index 4667044e4a66..95b0ce071166 100644
--- a/cxl/event_trace.c
+++ b/cxl/event_trace.c
@@ -235,3 +235,19 @@ int cxl_parse_events(struct tracefs_instance *inst, struct event_ctx *ectx)
 	tep_free(tep);
 	return rc;
 }
+
+int cxl_event_tracing_enable(struct tracefs_instance *inst, const char *system,
+		const char *event)
+{
+	int rc;
+
+	rc = tracefs_event_enable(inst, system, event);
+	if (rc == -1)
+		return -errno;
+
+	if (tracefs_trace_is_on(inst))
+		return 0;
+
+	tracefs_trace_on(inst);
+	return 0;
+}
diff --git a/cxl/event_trace.h b/cxl/event_trace.h
index 582882c1eb35..aecf9aa96187 100644
--- a/cxl/event_trace.h
+++ b/cxl/event_trace.h
@@ -20,5 +20,7 @@ struct event_ctx {
 };
 
 int cxl_parse_events(struct tracefs_instance *inst, struct event_ctx *ectx);
+int cxl_event_tracing_enable(struct tracefs_instance *inst, const char *system,
+		const char *event);
 
 #endif

[PATCH v4 04/10] cxl: add common function to disable event trace

[Dave Jiang]

Add a common function for cxl command that disables the event trace for the
instance created.

Signed-off-by: Dave Jiang <dave.jiang@intel.com>
---
 cxl/event_trace.c |    5 +++++
 cxl/event_trace.h |    1 +
 2 files changed, 6 insertions(+)

diff --git a/cxl/event_trace.c b/cxl/event_trace.c
index 95b0ce071166..490c30e1dbfc 100644
--- a/cxl/event_trace.c
+++ b/cxl/event_trace.c
@@ -251,3 +251,8 @@ int cxl_event_tracing_enable(struct tracefs_instance *inst, const char *system,
 	tracefs_trace_on(inst);
 	return 0;
 }
+
+int cxl_event_tracing_disable(struct tracefs_instance *inst)
+{
+	return tracefs_trace_off(inst);
+}
diff --git a/cxl/event_trace.h b/cxl/event_trace.h
index aecf9aa96187..89e98cafb320 100644
--- a/cxl/event_trace.h
+++ b/cxl/event_trace.h
@@ -22,5 +22,6 @@ struct event_ctx {
 int cxl_parse_events(struct tracefs_instance *inst, struct event_ctx *ectx);
 int cxl_event_tracing_enable(struct tracefs_instance *inst, const char *system,
 		const char *event);
+int cxl_event_tracing_disable(struct tracefs_instance *inst);
 
 #endif

[PATCH v4 05/10] cxl: add monitor function for event trace events

[Dave Jiang]

Add function that creates an event trace instance and utilize the cxl event
trace common functions to extract interested events from the trace buffer.
The monitoring function will pend on an epoll fd and wait for new events
to appear in the trace buffer.

Signed-off-by: Dave Jiang <dave.jiang@intel.com>
---
 cxl/meson.build |    1 
 cxl/monitor.c   |  140 +++++++++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 141 insertions(+)
 create mode 100644 cxl/monitor.c

diff --git a/cxl/meson.build b/cxl/meson.build
index c59876262e76..eb8b2b1070ed 100644
--- a/cxl/meson.build
+++ b/cxl/meson.build
@@ -8,6 +8,7 @@ cxl_src = [
   'json.c',
   'filter.c',
   'event_trace.c',
+  'monitor.c',
 ]
 
 cxl_tool = executable('cxl',
diff --git a/cxl/monitor.c b/cxl/monitor.c
new file mode 100644
index 000000000000..c3f7e3639ec0
--- /dev/null
+++ b/cxl/monitor.c
@@ -0,0 +1,140 @@
+// SPDX-License-Identifier: GPL-2.0
+// Copyright (C) 2022, Intel Corp. All rights reserved.
+/* Some bits copied from ndctl monitor code */
+#include <stdio.h>
+#include <unistd.h>
+#include <errno.h>
+#include <json-c/json.h>
+#include <libgen.h>
+#include <time.h>
+#include <dirent.h>
+#include <ccan/list/list.h>
+#include <util/json.h>
+#include <util/util.h>
+#include <util/parse-options.h>
+#include <util/parse-configs.h>
+#include <util/strbuf.h>
+#include <sys/epoll.h>
+#include <sys/stat.h>
+#include <traceevent/event-parse.h>
+#include <tracefs/tracefs.h>
+#include <cxl/libcxl.h>
+
+/* reuse the core log helpers for the monitor logger */
+#ifndef ENABLE_LOGGING
+#define ENABLE_LOGGING
+#endif
+#ifndef ENABLE_DEBUG
+#define ENABLE_DEBUG
+#endif
+#include <util/log.h>
+
+#include "event_trace.h"
+
+static const char *cxl_system = "cxl";
+
+static struct monitor {
+	struct log_ctx ctx;
+	FILE *log_file;
+	bool human;
+} monitor;
+
+static int monitor_event(struct cxl_ctx *ctx)
+{
+	int fd, epollfd, rc = 0, timeout = -1;
+	struct epoll_event ev, *events;
+	struct tracefs_instance *inst;
+	struct event_ctx ectx;
+	int jflag;
+
+	events = calloc(1, sizeof(struct epoll_event));
+	if (!events) {
+		err(&monitor, "alloc for events error\n");
+		return -ENOMEM;
+	}
+
+	epollfd = epoll_create1(0);
+	if (epollfd == -1) {
+		rc = -errno;
+		err(&monitor, "epoll_create1() error: %d\n", rc);
+		goto epoll_err;
+	}
+
+	inst = tracefs_instance_create("cxl_monitor");
+	if (!inst) {
+		rc = -errno;
+		err(&monitor, "tracefs_instance_create( failed: %d\n", rc);
+		goto inst_err;
+	}
+
+	fd = tracefs_instance_file_open(inst, "trace_pipe", -1);
+	if (fd < 0) {
+		rc = fd;
+		err(&monitor, "tracefs_instance_file_open() err: %d\n", rc);
+		goto inst_file_err;
+	}
+
+	memset(&ev, 0, sizeof(ev));
+	ev.events = EPOLLIN;
+	ev.data.fd = fd;
+
+	if (epoll_ctl(epollfd, EPOLL_CTL_ADD, fd, &ev) != 0) {
+		rc = -errno;
+		err(&monitor, "epoll_ctl() error: %d\n", rc);
+		goto epoll_ctl_err;
+	}
+
+	rc = cxl_event_tracing_enable(inst, cxl_system, NULL);
+	if (rc < 0) {
+		err(&monitor, "cxl_trace_event_enable() failed: %d\n", rc);
+		goto event_en_err;
+	}
+
+	memset(&ectx, 0, sizeof(ectx));
+	ectx.system = cxl_system;
+	if (monitor.human)
+		jflag = JSON_C_TO_STRING_PRETTY;
+	else
+		jflag = JSON_C_TO_STRING_PLAIN;
+
+	while (1) {
+		struct jlist_node *jnode, *next;
+
+		rc = epoll_wait(epollfd, events, 1, timeout);
+		if (rc < 0) {
+			rc = -errno;
+			if (errno != EINTR)
+				err(&monitor, "epoll_wait error: %d\n", -errno);
+			break;
+		}
+
+		list_head_init(&ectx.jlist_head);
+		rc = cxl_parse_events(inst, &ectx);
+		if (rc < 0)
+			goto parse_err;
+
+		if (list_empty(&ectx.jlist_head))
+			continue;
+
+		list_for_each_safe(&ectx.jlist_head, jnode, next, list) {
+			notice(&monitor, "%s\n",
+				json_object_to_json_string_ext(jnode->jobj, jflag));
+			list_del(&jnode->list);
+			json_object_put(jnode->jobj);
+			free(jnode);
+		}
+	}
+
+parse_err:
+	rc = cxl_event_tracing_disable(inst);
+event_en_err:
+epoll_ctl_err:
+	close(fd);
+inst_file_err:
+	tracefs_instance_free(inst);
+inst_err:
+	close(epollfd);
+epoll_err:
+	free(events);
+	return rc;
+}

[PATCH v4 06/10] cxl: add logging functions for monitor

[Dave Jiang]

Duplicate log functions from ndctl/monitor to use for stdout and file
logging.

Signed-off-by: Dave Jiang <dave.jiang@gmail.com>
---
 cxl/monitor.c |   25 +++++++++++++++++++++++++
 1 file changed, 25 insertions(+)

diff --git a/cxl/monitor.c b/cxl/monitor.c
index c3f7e3639ec0..518d8142e40d 100644
--- a/cxl/monitor.c
+++ b/cxl/monitor.c
@@ -39,6 +39,31 @@ static struct monitor {
 	bool human;
 } monitor;
 
+static void log_standard(struct log_ctx *ctx, int priority, const char *file,
+		int line, const char *fn, const char *format, va_list args)
+{
+	if (priority == 6)
+		vfprintf(stdout, format, args);
+	else
+		vfprintf(stderr, format, args);
+}
+
+static void log_file(struct log_ctx *ctx, int priority, const char *file,
+		int line, const char *fn, const char *format, va_list args)
+{
+	FILE *f = monitor.log_file;
+
+	if (priority != LOG_NOTICE) {
+		struct timespec ts;
+
+		clock_gettime(CLOCK_REALTIME, &ts);
+		fprintf(f, "[%10ld.%09ld] [%d] ", ts.tv_sec, ts.tv_nsec, getpid());
+	}
+
+	vfprintf(f, format, args);
+	fflush(f);
+}
+
 static int monitor_event(struct cxl_ctx *ctx)
 {
 	int fd, epollfd, rc = 0, timeout = -1;

[PATCH v4 07/10] cxl: add monitor command to cxl

[Dave Jiang]

Connect the monitoring functionality to the cxl monitor command. Add basic
functionality to the cxl monitor command where it can be launched as a daemon
and logging can be designated to stdout or a file.

Signed-off-by: Dave Jiang <dave.jiang@intel.com>
---
 cxl/builtin.h |    1 +
 cxl/cxl.c     |    1 +
 cxl/monitor.c |   75 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 77 insertions(+)

diff --git a/cxl/builtin.h b/cxl/builtin.h
index b28c2213993b..34c5cfb49051 100644
--- a/cxl/builtin.h
+++ b/cxl/builtin.h
@@ -22,4 +22,5 @@ int cmd_create_region(int argc, const char **argv, struct cxl_ctx *ctx);
 int cmd_enable_region(int argc, const char **argv, struct cxl_ctx *ctx);
 int cmd_disable_region(int argc, const char **argv, struct cxl_ctx *ctx);
 int cmd_destroy_region(int argc, const char **argv, struct cxl_ctx *ctx);
+int cmd_monitor(int argc, const char **argv, struct cxl_ctx *ctx);
 #endif /* _CXL_BUILTIN_H_ */
diff --git a/cxl/cxl.c b/cxl/cxl.c
index dd1be7a054a1..3be7026f43d3 100644
--- a/cxl/cxl.c
+++ b/cxl/cxl.c
@@ -76,6 +76,7 @@ static struct cmd_struct commands[] = {
 	{ "enable-region", .c_fn = cmd_enable_region },
 	{ "disable-region", .c_fn = cmd_disable_region },
 	{ "destroy-region", .c_fn = cmd_destroy_region },
+	{ "monitor", .c_fn = cmd_monitor },
 };
 
 int main(int argc, const char **argv)
diff --git a/cxl/monitor.c b/cxl/monitor.c
index 518d8142e40d..d8e498392ed7 100644
--- a/cxl/monitor.c
+++ b/cxl/monitor.c
@@ -32,11 +32,15 @@
 #include "event_trace.h"
 
 static const char *cxl_system = "cxl";
+const char *default_log = "/var/log/cxl-monitor.log";
 
 static struct monitor {
+	const char *log;
 	struct log_ctx ctx;
 	FILE *log_file;
 	bool human;
+	bool verbose;
+	bool daemon;
 } monitor;
 
 static void log_standard(struct log_ctx *ctx, int priority, const char *file,
@@ -163,3 +167,74 @@ epoll_err:
 	free(events);
 	return rc;
 }
+
+int cmd_monitor(int argc, const char **argv, struct cxl_ctx *ctx)
+{
+	const struct option options[] = {
+		OPT_FILENAME('l', "log", &monitor.log,
+				"<file> | standard",
+				"where to output the monitor's notification"),
+		OPT_BOOLEAN('\0', "daemon", &monitor.daemon,
+				"run cxl monitor as a daemon"),
+		OPT_BOOLEAN('u', "human", &monitor.human,
+				"use human friendly output formats"),
+		OPT_BOOLEAN('v', "verbose", &monitor.verbose,
+				"emit extra debug messages to log"),
+		OPT_END(),
+	};
+	const char * const u[] = {
+		"cxl monitor [<options>]",
+		NULL
+	};
+	const char *prefix ="./";
+	int rc = 0, i;
+
+	argc = parse_options_prefix(argc, argv, prefix, options, u, 0);
+	for (i = 0; i < argc; i++)
+		error("unknown parameter \"%s\"\n", argv[i]);
+	if (argc)
+		usage_with_options(u, options);
+
+	log_init(&monitor.ctx, "cxl/monitor", "CXL_MONITOR_LOG");
+	monitor.ctx.log_fn = log_standard;
+
+	if (monitor.verbose)
+		monitor.ctx.log_priority = LOG_DEBUG;
+	else
+		monitor.ctx.log_priority = LOG_INFO;
+
+	if (monitor.log) {
+		if (strncmp(monitor.log, "./", 2) != 0)
+			fix_filename(prefix, (const char **)&monitor.log);
+		if (strncmp(monitor.log, "./standard", 10) == 0 && !monitor.daemon) {
+			monitor.ctx.log_fn = log_standard;
+		} else {
+			const char *log = monitor.log;
+
+			if (!monitor.log)
+				log = default_log;
+			monitor.log_file = fopen(log, "a+");
+			if (!monitor.log_file) {
+				rc = -errno;
+				error("open %s failed: %d\n", monitor.log, rc);
+				goto out;
+			}
+			monitor.ctx.log_fn = log_file;
+		}
+	}
+
+	if (monitor.daemon) {
+		if (daemon(0, 0) != 0) {
+			err(&monitor, "daemon start failed\n");
+			goto out;
+		}
+		info(&monitor, "cxl monitor daemon started.\n");
+	}
+
+	rc = monitor_event(ctx);
+
+out:
+	if (monitor.log_file)
+		fclose(monitor.log_file);
+	return rc;
+}

[PATCH v4 08/10] cxl: add an optional pid check to event parsing

[Dave Jiang]

From: Alison Schofield <alison.schofield@intel.com>

When parsing CXL events, callers may only be interested in events
that originate from the current process. Introduce an optional
argument to the event trace context: event_pid. When event_pid is
present, only include events with a matching pid in the returned
JSON list. It is not a failure to see other, non matching results.
Simply skip those.

The initial use case for this is the listing of media errors,
where only the media-errors requested by this process are wanted.

Signed-off-by: Alison Schofield <alison.schofield@intel.com>
Signed-off-by: Dave Jiang <dave.jiang@intel.com>
---
 cxl/event_trace.c |    5 +++++
 cxl/event_trace.h |    1 +
 2 files changed, 6 insertions(+)

diff --git a/cxl/event_trace.c b/cxl/event_trace.c
index 490c30e1dbfc..89c9c2db26a3 100644
--- a/cxl/event_trace.c
+++ b/cxl/event_trace.c
@@ -215,6 +215,11 @@ static int cxl_event_parse_cb(struct tep_event *event, struct tep_record *record
 			return 0;
 	}
 
+	if (event_ctx->event_pid) {
+		if (event_ctx->event_pid != tep_data_pid(event->tep, record))
+			return 0;
+	}
+
 	if (event_ctx->parse_event)
 		return event_ctx->parse_event(event, record, &event_ctx->jlist_head);
 
diff --git a/cxl/event_trace.h b/cxl/event_trace.h
index 89e98cafb320..e72b4347175e 100644
--- a/cxl/event_trace.h
+++ b/cxl/event_trace.h
@@ -15,6 +15,7 @@ struct event_ctx {
 	const char *system;
 	struct list_head jlist_head;
 	const char *event_name;					/* optional */
+	int event_pid;						/* optional */
 	int (*parse_event)(struct tep_event *event, struct tep_record *record,
 			   struct list_head *jlist_head);	/* optional */
 };

[PATCH v4 09/10] cxl: add systemd service for monitor

[Dave Jiang]

Add a systemd service file for cxl monitor to start the monitoring service
on boot initialization. Add the installation setup for the service file.

Signed-off-by: Dave Jiang <dave.jiang@intel.com>
---
 cxl/cxl-monitor.service |    9 +++++++++
 cxl/meson.build         |    4 ++++
 ndctl.spec.in           |    1 +
 3 files changed, 14 insertions(+)
 create mode 100644 cxl/cxl-monitor.service

diff --git a/cxl/cxl-monitor.service b/cxl/cxl-monitor.service
new file mode 100644
index 000000000000..87c842b6f595
--- /dev/null
+++ b/cxl/cxl-monitor.service
@@ -0,0 +1,9 @@
+[Unit]
+Description=Cxl Monitor Daemon
+
+[Service]
+Type=simple
+ExecStart=/usr/bin/cxl monitor
+
+[Install]
+WantedBy=multi-user.target
diff --git a/cxl/meson.build b/cxl/meson.build
index eb8b2b1070ed..fc2e946707a8 100644
--- a/cxl/meson.build
+++ b/cxl/meson.build
@@ -11,6 +11,10 @@ cxl_src = [
   'monitor.c',
 ]
 
+if get_option('systemd').enabled()
+  install_data('cxl-monitor.service', install_dir : systemdunitdir)
+endif
+
 cxl_tool = executable('cxl',
   cxl_src,
   include_directories : root_inc,
diff --git a/ndctl.spec.in b/ndctl.spec.in
index cfcafa2ba816..c883317c5ce7 100644
--- a/ndctl.spec.in
+++ b/ndctl.spec.in
@@ -194,6 +194,7 @@ fi
 %{_bindir}/cxl
 %{_mandir}/man1/cxl*
 %{bashcompdir}/cxl
+%{_unitdir}/cxl-monitor.service
 
 %files -n LNAME
 %defattr(-,root,root)

[PATCH v4 10/10] cxl: add man page documentation for monitor

[Dave Jiang]

Add man page documentation to explain the usage of cxl monitor.

Signed-off-by: Dave Jiang <dave.jiang@intel.com>
---
 Documentation/cxl/cxl-monitor.txt |   77 +++++++++++++++++++++++++++++++++++++
 1 file changed, 77 insertions(+)
 create mode 100644 Documentation/cxl/cxl-monitor.txt

diff --git a/Documentation/cxl/cxl-monitor.txt b/Documentation/cxl/cxl-monitor.txt
new file mode 100644
index 000000000000..43c2ece72220
--- /dev/null
+++ b/Documentation/cxl/cxl-monitor.txt
@@ -0,0 +1,77 @@
+// SPDX-License-Identifier: GPL-2.0
+
+cxl-monitor(1)
+================
+
+NAME
+----
+cxl-monitor - Monitor the CXL kernel trace events
+
+SYNOPSIS
+--------
+[verse]
+'cxl monitor' [<options>]
+
+DESCRIPTION
+-----------
+Cxl monitor is used for monitoring the CXL trace events emitted by
+the kernel and convert them to json objects and dumping the json format
+notifications to standard output or a logfile.
+
+Both, the values in configuration file and in options will work. If
+there is a conflict, the values in options will override the values in
+the configuration file. Any updated values in the configuration file will
+take effect only after the monitor process is restarted.
+
+EXAMPLES
+--------
+
+Run a monitor as a daemon to monitor events and output to a log file.
+[verse]
+cxl monitor --daemon --log=/var/log/cxl-monitor.log
+
+Run a monitor as a one-shot command and output the notifications to stdio.
+[verse]
+cxl monitor
+
+Run a monitor daemon as a system service
+[verse]
+systemctl start cxl-monitor.service
+
+OPTIONS
+-------
+-l::
+--log=::
+	Send log messages to the specified destination.
+	- "<file>":
+	  Send log messages to specified <file>. When fopen() is not able
+	  to open <file>, log messages will be forwarded to syslog.
+	- "standard":
+	  Send messages to standard output.
+
+The default log destination is '/var/log/cxl-monitor.log' if "--daemon" is specified,
+otherwise 'standard'. Note that standard and relative path for <file>
+will not work if "--daemon" is specified.
+
+--daemon::
+	Run a monitor as a daemon.
+
+-u::
+--human::
+	Output monitor notification as human friendly json format instead
+	of the default machine friendly json format.
+
+-v::
+--verbose::
+	Emit extra debug messages to log.
+
+COPYRIGHT
+---------
+Copyright (c) 2022, Intel Corp. License GPLv2: GNU GPL version 2
+<http://gnu.org/licenses/gpl.html>. This is free software: you are
+free to change and redistribute it. There is NO WARRANTY, to the
+extent permitted by law.
+
+SEE ALSO
+--------
+linkcxl:cxl-list[1]

Re: [PATCH v4 01/10] cxl: add helper function to parse trace event to json object

[Verma, Vishal L]

On Tue, 2022-11-08 at 11:29 -0700, Dave Jiang wrote:
> Add the helper function that parses a trace event captured by
> libtraceevent in a tep handle. All the parsed fields are added to a json
> object. The json object is added to the provided list in the input parameter.
> 
> Tested-by: Alison Schofield <alison.schofield@intel.com>
> Signed-off-by: Dave Jiang <dave.jiang@intel.com>
> ---
>  cxl/event_trace.c |  201 +++++++++++++++++++++++++++++++++++++++++++++++++++++
>  cxl/event_trace.h |   14 ++++
>  cxl/meson.build   |    2 +
>  meson.build       |    1 
>  4 files changed, 218 insertions(+)
>  create mode 100644 cxl/event_trace.c
>  create mode 100644 cxl/event_trace.h
> 
> diff --git a/cxl/event_trace.c b/cxl/event_trace.c
> new file mode 100644
> index 000000000000..1b1b037e48bf
> --- /dev/null
> +++ b/cxl/event_trace.c
> @@ -0,0 +1,201 @@
> +// SPDX-License-Identifier: GPL-2.0
> +// Copyright (C) 2022, Intel Corp. All rights reserved.
> +#include <stdio.h>
> +#include <json-c/json.h>
> +#include <util/json.h>
> +#include <util/util.h>
> +#include <util/parse-options.h>
> +#include <util/parse-configs.h>

The above two seem unnecessary.

> +#include <util/strbuf.h>
> +#include <util/sysfs.h>

Same with this.

> +#include <ccan/list/list.h>
> +#include <ndctl/ndctl.h>
> +#include <ndctl/libndctl.h>

Are the ndctl includes needed for anything?

> +#include <sys/epoll.h>
> +#include <sys/stat.h>

These two look unused too.

> +#include <libcxl.h>

This could be dropped too.

> +#include <uuid/uuid.h>
> +#include <traceevent/event-parse.h>
> +#include "json.h"
> +#include "event_trace.h"
> +
> +#define _GNU_SOURCE
> +#include <string.h>
> +
> +static struct json_object *num_to_json(void *num, int elem_size, unsigned long flags)
> +{
> +       bool sign = flags & TEP_FIELD_IS_SIGNED;
> +       int64_t val = 0;
> +
> +       /* special case 64 bit as the call depends on sign */
> +       if (elem_size == 8) {
> +               if (sign)
> +                       return json_object_new_int64(*(int64_t *)num);
> +               else
> +                       return json_object_new_uint64(*(uint64_t *)num);
> +       }
> +
> +       /* All others fit in a signed 64 bit */
> +       switch (elem_size) {
> +       case 1:
> +               if (sign)
> +                       val = *(int8_t *)num;
> +               else
> +                       val = *(uint8_t *)num;
> +               break;
> +       case 2:
> +               if (sign)
> +                       val = *(int16_t *)num;
> +               else
> +                       val = *(uint16_t *)num;
> +               break;
> +       case 4:
> +               if (sign)
> +                       val = *(int32_t *)num;
> +               else
> +                       val = *(uint32_t *)num;
> +               break;
> +       default:
> +               /*
> +                * Odd sizes are converted in the kernel to one of the above.
> +                * It is an error to see them here.
> +                */
> +               return NULL;
> +       }
> +
> +       return json_object_new_int64(val);
> +}
> +
> +static int cxl_event_to_json_callback(struct tep_event *event,
> +               struct tep_record *record, struct list_head *jlist_head)

Instead of the old double-tab style continuations, we added a .clang-
format to ndctl, which will format this slightly differently (matching
the continuation to the first char after the opening parens).

Also, is 'callback' in the name useful? I'd consider dropping it -
'cxl_event_to_json' conveys just as much information about what it
does.

> +{
> +       struct tep_format_field **fields;
> +       struct json_object *jevent, *jobj, *jarray;

Minor/optional nit, but these look nice and clean in reverse-christmas
tree used elsewhere :)

> +       struct jlist_node *jnode;
> +       int i, j, rc = 0;
> +
> +       jnode = malloc(sizeof(*jnode));
> +       if (!jnode)
> +               return -ENOMEM;
> +
> +       jevent = json_object_new_object();
> +       if (!jevent) {
> +               rc = -ENOMEM;
> +               goto err_jevent;

Also minor, but the label should probably be called err_free or
something since you goto it before jevent needs to be freed.

> +       }
> +       jnode->jobj = jevent;
> +
> +       fields = tep_event_fields(event);
> +       if (!fields) {
> +               rc = -ENOENT;
> +               goto err;
> +       }
> +
> +       jobj = json_object_new_string(event->system);
> +       if (!jobj) {
> +               rc = -ENOMEM;
> +               goto err;
> +       }
> +       json_object_object_add(jevent, "system", jobj);
> +
> +       jobj = json_object_new_string(event->name);
> +       if (!jobj) {
> +               rc = -ENOMEM;
> +               goto err;
> +       }
> +       json_object_object_add(jevent, "event", jobj);
> +
> +       jobj = json_object_new_uint64(record->ts);
> +       if (!jobj) {
> +               rc = -ENOMEM;
> +               goto err;
> +       }
> +       json_object_object_add(jevent, "timestamp", jobj);
> +
> +       for (i = 0; fields[i]; i++) {
> +               struct tep_format_field *f = fields[i];
> +               int len;
> +
> +               if (f->flags & TEP_FIELD_IS_STRING) {
> +                       char *str;
> +
> +                       str = tep_get_field_raw(NULL, event, f->name, record, &len, 0);
> +                       if (!str)
> +                               continue;
> +
> +                       jobj = json_object_new_string(str);
> +                       if (!jobj) {
> +                               rc = -ENOMEM;
> +                               goto err;
> +                       }
> +
> +                       json_object_object_add(jevent, f->name, jobj);
> +               } else if (f->flags & TEP_FIELD_IS_ARRAY) {
> +                       unsigned char *data;
> +                       int chunks;
> +
> +                       data = tep_get_field_raw(NULL, event, f->name, record, &len, 0);
> +                       if (!data)
> +                               continue;
> +
> +                       jarray = json_object_new_array();
> +                       if (!jarray) {
> +                               rc = -ENOMEM;
> +                               goto err;
> +                       }
> +
> +                       chunks = f->size / f->elementsize;
> +                       for (j = 0; j < chunks; j++) {
> +                               jobj = num_to_json(data, f->elementsize, f->flags);
> +                               if (!jobj) {
> +                                       json_object_put(jarray);
> +                                       return -ENOMEM;
> +                               }
> +                               json_object_array_add(jarray, jobj);
> +                               data += f->elementsize;
> +                       }
> +
> +                       json_object_object_add(jevent, f->name, jarray);
> +               } else { /* single number */
> +                       unsigned char *data;
> +                       char *tmp;
> +
> +                       data = tep_get_field_raw(NULL, event, f->name, record, &len, 0);
> +                       if (!data)
> +                               continue;
> +
> +                       /* check to see if we have a UUID */
> +                       tmp = strcasestr(f->type, "uuid_t");
> +                       if (tmp) {
> +                               char uuid[SYSFS_ATTR_SIZE];

Does this need to be SYSFS_ATTR_SIZE? Looks like historically we've
just created such UUID buffers to be buf[40]. I think the sysfs size is
4096.

> +
> +                               uuid_unparse(data, uuid);
> +                               jobj = json_object_new_string(uuid);
> +                               if (!jobj) {
> +                                       rc = -ENOMEM;
> +                                       goto err;
> +                               }
> +
> +                               json_object_object_add(jevent, f->name, jobj);
> +                               continue;
> +                       }
> +
> +                       jobj = num_to_json(data, f->elementsize, f->flags);
> +                       if (!jobj) {
> +                               rc = -ENOMEM;
> +                               goto err;
> +                       }
> +
> +                       json_object_object_add(jevent, f->name, jobj);
> +               }
> +       }
> +
> +       list_add_tail(jlist_head, &jnode->list);
> +       return 0;
> +
> +err:
> +       json_object_put(jevent);
> +err_jevent:
> +       free(jnode);
> +       return rc;
> +}
> diff --git a/cxl/event_trace.h b/cxl/event_trace.h
> new file mode 100644
> index 000000000000..00975a0b5680
> --- /dev/null
> +++ b/cxl/event_trace.h
> @@ -0,0 +1,14 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +/* Copyright (C) 2022 Intel Corporation. All rights reserved. */
> +#ifndef __CXL_EVENT_TRACE_H__
> +#define __CXL_EVENT_TRACE_H__
> +
> +#include <json-c/json.h>
> +#include <ccan/list/list.h>
> +
> +struct jlist_node {
> +       struct json_object *jobj;
> +       struct list_node list;
> +};
> +
> +#endif
> diff --git a/cxl/meson.build b/cxl/meson.build
> index f2474aaa6e2e..8c7733431613 100644
> --- a/cxl/meson.build
> +++ b/cxl/meson.build
> @@ -7,6 +7,7 @@ cxl_src = [
>    'memdev.c',
>    'json.c',
>    'filter.c',
> +  'event_trace.c',
>  ]
>  
>  cxl_tool = executable('cxl',
> @@ -19,6 +20,7 @@ cxl_tool = executable('cxl',
>      kmod,
>      json,
>      versiondep,
> +    traceevent,
>    ],
>    install : true,
>    install_dir : rootbindir,
> diff --git a/meson.build b/meson.build
> index 20a646d135c7..f611e0bdd7f3 100644
> --- a/meson.build
> +++ b/meson.build
> @@ -142,6 +142,7 @@ kmod = dependency('libkmod')
>  libudev = dependency('libudev')
>  uuid = dependency('uuid')
>  json = dependency('json-c')
> +traceevent = dependency('libtraceevent')
>  if get_option('docs').enabled()
>    if get_option('asciidoctor').enabled()
>      asciidoc = find_program('asciidoctor', required : true)
> 
> 

Re: [PATCH v4 02/10] cxl: add helper to parse through all current events

[Verma, Vishal L]

On Tue, 2022-11-08 at 11:29 -0700, Dave Jiang wrote:
> Add common function to iterate through and extract the events in the
> current trace buffer. The function uses tracefs_iterate_raw_events() from
> libtracefs to go through all the events loaded into a tep_handle. A
> callback is provided to the API call in order to parse the event. For cxl
> monitor, an array of interested "systems" is provided in order to filter

I couldn't tell what a 'system' means here - maybe clarify that?

> for the interested events.

s/interested events/events of interest/ ?

> 
> Tested-by: Alison Schofield <alison.schofield@intel.com>
> Signed-off-by: Dave Jiang <dave.jiang@intel.com>
> ---
>  cxl/event_trace.c |   36 ++++++++++++++++++++++++++++++++++++
>  cxl/event_trace.h |   10 ++++++++++
>  cxl/meson.build   |    1 +
>  meson.build       |    2 ++
>  4 files changed, 49 insertions(+)
> 
> diff --git a/cxl/event_trace.c b/cxl/event_trace.c
> index 1b1b037e48bf..4667044e4a66 100644
> --- a/cxl/event_trace.c
> +++ b/cxl/event_trace.c
> @@ -16,6 +16,7 @@
>  #include <libcxl.h>
>  #include <uuid/uuid.h>
>  #include <traceevent/event-parse.h>
> +#include <tracefs/tracefs.h>
>  #include "json.h"
>  #include "event_trace.h"
>  
> @@ -199,3 +200,38 @@ err_jevent:
>         free(jnode);
>         return rc;
>  }
> +
> +static int cxl_event_parse_cb(struct tep_event *event, struct tep_record *record,
> +               int cpu, void *ctx)

What does the _cb mean? I couldn't tell from what it's parsing what it
stands for - might be better to expand it?

> +{
> +       struct event_ctx *event_ctx = (struct event_ctx *)ctx;
> +
> +       /* Filter out all the events that the caller isn't interested in. */
> +       if (strcmp(event->system, event_ctx->system) != 0)
> +               return 0;
> +
> +       if (event_ctx->event_name) {
> +               if (strcmp(event->name, event_ctx->event_name) != 0)
> +                       return 0;
> +       }
> +
> +       if (event_ctx->parse_event)
> +               return event_ctx->parse_event(event, record, &event_ctx->jlist_head);
> +
> +       return cxl_event_to_json_callback(event, record, &event_ctx->jlist_head);
> +}
> +
> +int cxl_parse_events(struct tracefs_instance *inst, struct event_ctx *ectx)
> +{
> +       struct tep_handle *tep;
> +       int rc;
> +
> +       tep = tracefs_local_events(NULL);
> +       if (!tep)
> +               return -ENOMEM;
> +
> +       rc = tracefs_iterate_raw_events(tep, inst, NULL, 0,
> +                       cxl_event_parse_cb, ectx);
> +       tep_free(tep);
> +       return rc;
> +}
> diff --git a/cxl/event_trace.h b/cxl/event_trace.h
> index 00975a0b5680..582882c1eb35 100644
> --- a/cxl/event_trace.h
> +++ b/cxl/event_trace.h
> @@ -11,4 +11,14 @@ struct jlist_node {
>         struct list_node list;
>  };
>  
> +struct event_ctx {
> +       const char *system;
> +       struct list_head jlist_head;
> +       const char *event_name;                                 /* optional */
> +       int (*parse_event)(struct tep_event *event, struct tep_record *record,
> +                          struct list_head *jlist_head);       /* optional */
> +};
> +
> +int cxl_parse_events(struct tracefs_instance *inst, struct event_ctx *ectx);
> +
>  #endif
> diff --git a/cxl/meson.build b/cxl/meson.build
> index 8c7733431613..c59876262e76 100644
> --- a/cxl/meson.build
> +++ b/cxl/meson.build
> @@ -21,6 +21,7 @@ cxl_tool = executable('cxl',
>      json,
>      versiondep,
>      traceevent,
> +    tracefs,
>    ],
>    install : true,
>    install_dir : rootbindir,
> diff --git a/meson.build b/meson.build
> index f611e0bdd7f3..c204c8ac52de 100644
> --- a/meson.build
> +++ b/meson.build
> @@ -143,6 +143,8 @@ libudev = dependency('libudev')
>  uuid = dependency('uuid')
>  json = dependency('json-c')
>  traceevent = dependency('libtraceevent')
> +tracefs = dependency('libtracefs')
> +
>  if get_option('docs').enabled()
>    if get_option('asciidoctor').enabled()
>      asciidoc = find_program('asciidoctor', required : true)
> 
> 

Re: [PATCH v4 04/10] cxl: add common function to disable event trace

[Verma, Vishal L]

On Tue, 2022-11-08 at 11:30 -0700, Dave Jiang wrote:
> Add a common function for cxl command that disables the event trace for the
> instance created.
> 
> Signed-off-by: Dave Jiang <dave.jiang@intel.com>
> ---
>  cxl/event_trace.c |    5 +++++
>  cxl/event_trace.h |    1 +
>  2 files changed, 6 insertions(+)

This and the previous patch are very siomilar pre-requisite enabling -
I think they can be squashed into a single patch.

> 
> diff --git a/cxl/event_trace.c b/cxl/event_trace.c
> index 95b0ce071166..490c30e1dbfc 100644
> --- a/cxl/event_trace.c
> +++ b/cxl/event_trace.c
> @@ -251,3 +251,8 @@ int cxl_event_tracing_enable(struct tracefs_instance *inst, const char *system,
>         tracefs_trace_on(inst);
>         return 0;
>  }
> +
> +int cxl_event_tracing_disable(struct tracefs_instance *inst)
> +{
> +       return tracefs_trace_off(inst);
> +}
> diff --git a/cxl/event_trace.h b/cxl/event_trace.h
> index aecf9aa96187..89e98cafb320 100644
> --- a/cxl/event_trace.h
> +++ b/cxl/event_trace.h
> @@ -22,5 +22,6 @@ struct event_ctx {
>  int cxl_parse_events(struct tracefs_instance *inst, struct event_ctx *ectx);
>  int cxl_event_tracing_enable(struct tracefs_instance *inst, const char *system,
>                 const char *event);
> +int cxl_event_tracing_disable(struct tracefs_instance *inst);
>  
>  #endif
> 
> 

Re: [PATCH v4 06/10] cxl: add logging functions for monitor

[Verma, Vishal L]

On Tue, 2022-11-08 at 11:30 -0700, Dave Jiang wrote:
> Duplicate log functions from ndctl/monitor to use for stdout and file
> logging.
> 
> Signed-off-by: Dave Jiang <dave.jiang@gmail.com>
> ---
>  cxl/monitor.c |   25 +++++++++++++++++++++++++
>  1 file changed, 25 insertions(+)

Hm we already have util/log.{c,h}. Lets move these and any other
relevant infra there, and then include those in ndctl/monitor and
cxl/monitor.

> 
> diff --git a/cxl/monitor.c b/cxl/monitor.c
> index c3f7e3639ec0..518d8142e40d 100644
> --- a/cxl/monitor.c
> +++ b/cxl/monitor.c
> @@ -39,6 +39,31 @@ static struct monitor {
>         bool human;
>  } monitor;
>  
> +static void log_standard(struct log_ctx *ctx, int priority, const char *file,
> +               int line, const char *fn, const char *format, va_list args)
> +{
> +       if (priority == 6)
> +               vfprintf(stdout, format, args);
> +       else
> +               vfprintf(stderr, format, args);
> +}
> +
> +static void log_file(struct log_ctx *ctx, int priority, const char *file,
> +               int line, const char *fn, const char *format, va_list args)
> +{
> +       FILE *f = monitor.log_file;
> +
> +       if (priority != LOG_NOTICE) {
> +               struct timespec ts;
> +
> +               clock_gettime(CLOCK_REALTIME, &ts);
> +               fprintf(f, "[%10ld.%09ld] [%d] ", ts.tv_sec, ts.tv_nsec, getpid());
> +       }
> +
> +       vfprintf(f, format, args);
> +       fflush(f);
> +}
> +
>  static int monitor_event(struct cxl_ctx *ctx)
>  {
>         int fd, epollfd, rc = 0, timeout = -1;
> 
> 

Re: [PATCH v4 07/10] cxl: add monitor command to cxl

[Verma, Vishal L]

On Tue, 2022-11-08 at 11:30 -0700, Dave Jiang wrote:
> Connect the monitoring functionality to the cxl monitor command. Add basic
> functionality to the cxl monitor command where it can be launched as a daemon
> and logging can be designated to stdout or a file.
> 
> Signed-off-by: Dave Jiang <dave.jiang@intel.com>
> ---
>  cxl/builtin.h |    1 +
>  cxl/cxl.c     |    1 +
>  cxl/monitor.c |   75 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++
>  3 files changed, 77 insertions(+)

Feels likee this patch should be squashed with patch 5. Unless there's
an underlying reason for the split I'm missing, the standalone addition
of the monitor_event() function doesn't do anything, and doesn't feel
like a clean break even for reviewability.

> 
> diff --git a/cxl/builtin.h b/cxl/builtin.h
> index b28c2213993b..34c5cfb49051 100644
> --- a/cxl/builtin.h
> +++ b/cxl/builtin.h
> @@ -22,4 +22,5 @@ int cmd_create_region(int argc, const char **argv, struct cxl_ctx *ctx);
>  int cmd_enable_region(int argc, const char **argv, struct cxl_ctx *ctx);
>  int cmd_disable_region(int argc, const char **argv, struct cxl_ctx *ctx);
>  int cmd_destroy_region(int argc, const char **argv, struct cxl_ctx *ctx);
> +int cmd_monitor(int argc, const char **argv, struct cxl_ctx *ctx);
>  #endif /* _CXL_BUILTIN_H_ */
> diff --git a/cxl/cxl.c b/cxl/cxl.c
> index dd1be7a054a1..3be7026f43d3 100644
> --- a/cxl/cxl.c
> +++ b/cxl/cxl.c
> @@ -76,6 +76,7 @@ static struct cmd_struct commands[] = {
>         { "enable-region", .c_fn = cmd_enable_region },
>         { "disable-region", .c_fn = cmd_disable_region },
>         { "destroy-region", .c_fn = cmd_destroy_region },
> +       { "monitor", .c_fn = cmd_monitor },
>  };
>  
>  int main(int argc, const char **argv)
> diff --git a/cxl/monitor.c b/cxl/monitor.c
> index 518d8142e40d..d8e498392ed7 100644
> --- a/cxl/monitor.c
> +++ b/cxl/monitor.c
> @@ -32,11 +32,15 @@
>  #include "event_trace.h"
>  
>  static const char *cxl_system = "cxl";
> +const char *default_log = "/var/log/cxl-monitor.log";
>  
>  static struct monitor {
> +       const char *log;
>         struct log_ctx ctx;
>         FILE *log_file;
>         bool human;
> +       bool verbose;
> +       bool daemon;
>  } monitor;
>  
>  static void log_standard(struct log_ctx *ctx, int priority, const char *file,
> @@ -163,3 +167,74 @@ epoll_err:
>         free(events);
>         return rc;
>  }
> +
> +int cmd_monitor(int argc, const char **argv, struct cxl_ctx *ctx)
> +{
> +       const struct option options[] = {
> +               OPT_FILENAME('l', "log", &monitor.log,
> +                               "<file> | standard",
> +                               "where to output the monitor's notification"),
> +               OPT_BOOLEAN('\0', "daemon", &monitor.daemon,
> +                               "run cxl monitor as a daemon"),
> +               OPT_BOOLEAN('u', "human", &monitor.human,
> +                               "use human friendly output formats"),
> +               OPT_BOOLEAN('v', "verbose", &monitor.verbose,
> +                               "emit extra debug messages to log"),
> +               OPT_END(),
> +       };
> +       const char * const u[] = {
> +               "cxl monitor [<options>]",
> +               NULL
> +       };
> +       const char *prefix ="./";
> +       int rc = 0, i;
> +
> +       argc = parse_options_prefix(argc, argv, prefix, options, u, 0);
> +       for (i = 0; i < argc; i++)
> +               error("unknown parameter \"%s\"\n", argv[i]);
> +       if (argc)
> +               usage_with_options(u, options);
> +
> +       log_init(&monitor.ctx, "cxl/monitor", "CXL_MONITOR_LOG");
> +       monitor.ctx.log_fn = log_standard;
> +
> +       if (monitor.verbose)
> +               monitor.ctx.log_priority = LOG_DEBUG;
> +       else
> +               monitor.ctx.log_priority = LOG_INFO;
> +
> +       if (monitor.log) {
> +               if (strncmp(monitor.log, "./", 2) != 0)
> +                       fix_filename(prefix, (const char **)&monitor.log);
> +               if (strncmp(monitor.log, "./standard", 10) == 0 && !monitor.daemon) {
> +                       monitor.ctx.log_fn = log_standard;
> +               } else {
> +                       const char *log = monitor.log;
> +
> +                       if (!monitor.log)
> +                               log = default_log;
> +                       monitor.log_file = fopen(log, "a+");
> +                       if (!monitor.log_file) {
> +                               rc = -errno;
> +                               error("open %s failed: %d\n", monitor.log, rc);
> +                               goto out;
> +                       }
> +                       monitor.ctx.log_fn = log_file;
> +               }
> +       }
> +
> +       if (monitor.daemon) {
> +               if (daemon(0, 0) != 0) {
> +                       err(&monitor, "daemon start failed\n");
> +                       goto out;
> +               }
> +               info(&monitor, "cxl monitor daemon started.\n");
> +       }
> +
> +       rc = monitor_event(ctx);
> +
> +out:
> +       if (monitor.log_file)
> +               fclose(monitor.log_file);
> +       return rc;
> +}
> 
> 

Re: [PATCH v4 08/10] cxl: add an optional pid check to event parsing

[Verma, Vishal L]

On Tue, 2022-11-08 at 11:30 -0700, Dave Jiang wrote:
> From: Alison Schofield <alison.schofield@intel.com>
> 
> When parsing CXL events, callers may only be interested in events
> that originate from the current process. Introduce an optional
> argument to the event trace context: event_pid. When event_pid is
> present, only include events with a matching pid in the returned
> JSON list. It is not a failure to see other, non matching results.
> Simply skip those.
> 
> The initial use case for this is the listing of media errors,
> where only the media-errors requested by this process are wanted.
> 
> Signed-off-by: Alison Schofield <alison.schofield@intel.com>
> Signed-off-by: Dave Jiang <dave.jiang@intel.com>
> ---
>  cxl/event_trace.c |    5 +++++
>  cxl/event_trace.h |    1 +
>  2 files changed, 6 insertions(+)

I might be missing something - but this patch is added at then end,
without subsequently using the event_pid in cxl-monitor? So why not
leave this to be part of the media errors patches?

> 
> diff --git a/cxl/event_trace.c b/cxl/event_trace.c
> index 490c30e1dbfc..89c9c2db26a3 100644
> --- a/cxl/event_trace.c
> +++ b/cxl/event_trace.c
> @@ -215,6 +215,11 @@ static int cxl_event_parse_cb(struct tep_event *event, struct tep_record *record
>                         return 0;
>         }
>  
> +       if (event_ctx->event_pid) {
> +               if (event_ctx->event_pid != tep_data_pid(event->tep, record))
> +                       return 0;
> +       }
> +
>         if (event_ctx->parse_event)
>                 return event_ctx->parse_event(event, record, &event_ctx->jlist_head);
>  
> diff --git a/cxl/event_trace.h b/cxl/event_trace.h
> index 89e98cafb320..e72b4347175e 100644
> --- a/cxl/event_trace.h
> +++ b/cxl/event_trace.h
> @@ -15,6 +15,7 @@ struct event_ctx {
>         const char *system;
>         struct list_head jlist_head;
>         const char *event_name;                                 /* optional */
> +       int event_pid;                                          /* optional */
>         int (*parse_event)(struct tep_event *event, struct tep_record *record,
>                            struct list_head *jlist_head);       /* optional */
>  };
> 
> 

Re: [PATCH v4 09/10] cxl: add systemd service for monitor

[Verma, Vishal L]

On Tue, 2022-11-08 at 11:30 -0700, Dave Jiang wrote:
> Add a systemd service file for cxl monitor to start the monitoring service
> on boot initialization. Add the installation setup for the service file.
> 
> Signed-off-by: Dave Jiang <dave.jiang@intel.com>
> ---
>  cxl/cxl-monitor.service |    9 +++++++++
>  cxl/meson.build         |    4 ++++
>  ndctl.spec.in           |    1 +
>  3 files changed, 14 insertions(+)
>  create mode 100644 cxl/cxl-monitor.service
> 
> diff --git a/cxl/cxl-monitor.service b/cxl/cxl-monitor.service
> new file mode 100644
> index 000000000000..87c842b6f595
> --- /dev/null
> +++ b/cxl/cxl-monitor.service
> @@ -0,0 +1,9 @@
> +[Unit]
> +Description=Cxl Monitor Daemon

s/Cxl/CXL/

> +
> +[Service]
> +Type=simple
> +ExecStart=/usr/bin/cxl monitor
> +
> +[Install]
> +WantedBy=multi-user.target
> diff --git a/cxl/meson.build b/cxl/meson.build
> index eb8b2b1070ed..fc2e946707a8 100644
> --- a/cxl/meson.build
> +++ b/cxl/meson.build
> @@ -11,6 +11,10 @@ cxl_src = [
>    'monitor.c',
>  ]
>  
> +if get_option('systemd').enabled()
> +  install_data('cxl-monitor.service', install_dir : systemdunitdir)
> +endif
> +
>  cxl_tool = executable('cxl',
>    cxl_src,
>    include_directories : root_inc,
> diff --git a/ndctl.spec.in b/ndctl.spec.in
> index cfcafa2ba816..c883317c5ce7 100644
> --- a/ndctl.spec.in
> +++ b/ndctl.spec.in
> @@ -194,6 +194,7 @@ fi
>  %{_bindir}/cxl
>  %{_mandir}/man1/cxl*
>  %{bashcompdir}/cxl
> +%{_unitdir}/cxl-monitor.service
>  
>  %files -n LNAME
>  %defattr(-,root,root)
> 
> 

Re: [PATCH v4 10/10] cxl: add man page documentation for monitor

[Verma, Vishal L]

On Tue, 2022-11-08 at 11:30 -0700, Dave Jiang wrote:
> Add man page documentation to explain the usage of cxl monitor.
> 
> Signed-off-by: Dave Jiang <dave.jiang@intel.com>
> ---
>  Documentation/cxl/cxl-monitor.txt |   77 +++++++++++++++++++++++++++++++++++++

Is this missing an update to a meson.build in Documentation/cxl?

>  1 file changed, 77 insertions(+)
>  create mode 100644 Documentation/cxl/cxl-monitor.txt
> 
> diff --git a/Documentation/cxl/cxl-monitor.txt b/Documentation/cxl/cxl-monitor.txt
> new file mode 100644
> index 000000000000..43c2ece72220
> --- /dev/null
> +++ b/Documentation/cxl/cxl-monitor.txt
> @@ -0,0 +1,77 @@
> +// SPDX-License-Identifier: GPL-2.0
> +
> +cxl-monitor(1)
> +================

Unaligned '===' line

> +
> +NAME
> +----
> +cxl-monitor - Monitor the CXL kernel trace events

Probably drop 'kernel' here.

> +
> +SYNOPSIS
> +--------
> +[verse]
> +'cxl monitor' [<options>]
> +
> +DESCRIPTION
> +-----------
> +Cxl monitor is used for monitoring the CXL trace events emitted by

s/Cxl/CXL/ or s/Cxl monitor/cxl-monitor/ I think.

> +the kernel and convert them to json objects and dumping the json format
> +notifications to standard output or a logfile.
> +
> +Both, the values in configuration file and in options will work. If

s/file/file,/

Also is config file support actually present yet?

> +there is a conflict, the values in options will override the values in
> +the configuration file. Any updated values in the configuration file will
> +take effect only after the monitor process is restarted.
> +
> +EXAMPLES
> +--------
> +
> +Run a monitor as a daemon to monitor events and output to a log file.
> +[verse]
> +cxl monitor --daemon --log=/var/log/cxl-monitor.log
> +
> +Run a monitor as a one-shot command and output the notifications to stdio.
> +[verse]
> +cxl monitor
> +
> +Run a monitor daemon as a system service
> +[verse]
> +systemctl start cxl-monitor.service
> +
> +OPTIONS
> +-------
> +-l::
> +--log=::
> +       Send log messages to the specified destination.
> +       - "<file>":
> +         Send log messages to specified <file>. When fopen() is not able
> +         to open <file>, log messages will be forwarded to syslog.
> +       - "standard":
> +         Send messages to standard output.
> +
> +The default log destination is '/var/log/cxl-monitor.log' if "--daemon" is specified,
> +otherwise 'standard'. Note that standard and relative path for <file>
> +will not work if "--daemon" is specified.
> +
> +--daemon::
> +       Run a monitor as a daemon.
> +
> +-u::
> +--human::
> +       Output monitor notification as human friendly json format instead
> +       of the default machine friendly json format.
> +
> +-v::
> +--verbose::
> +       Emit extra debug messages to log.
> +
> +COPYRIGHT
> +---------
> +Copyright (c) 2022, Intel Corp. License GPLv2: GNU GPL version 2
> +<http://gnu.org/licenses/gpl.html>. This is free software: you are
> +free to change and redistribute it. There is NO WARRANTY, to the
> +extent permitted by law.

I think there is an include for the copyright under Documentation/cxl,
as well as for human and verbose options.

> +
> +SEE ALSO
> +--------
> +linkcxl:cxl-list[1]
> 
> 

Re: [PATCH v4 01/10] cxl: add helper function to parse trace event to json object

[Dave Jiang]

On 11/8/2022 3:02 PM, Verma, Vishal L wrote:
> On Tue, 2022-11-08 at 11:29 -0700, Dave Jiang wrote:
>> Add the helper function that parses a trace event captured by
>> libtraceevent in a tep handle. All the parsed fields are added to a json
>> object. The json object is added to the provided list in the input parameter.
>>
>> Tested-by: Alison Schofield <alison.schofield@intel.com>
>> Signed-off-by: Dave Jiang <dave.jiang@intel.com>
>> ---
>>   cxl/event_trace.c |  201 +++++++++++++++++++++++++++++++++++++++++++++++++++++
>>   cxl/event_trace.h |   14 ++++
>>   cxl/meson.build   |    2 +
>>   meson.build       |    1
>>   4 files changed, 218 insertions(+)
>>   create mode 100644 cxl/event_trace.c
>>   create mode 100644 cxl/event_trace.h
>>
>> diff --git a/cxl/event_trace.c b/cxl/event_trace.c
>> new file mode 100644
>> index 000000000000..1b1b037e48bf
>> --- /dev/null
>> +++ b/cxl/event_trace.c
>> @@ -0,0 +1,201 @@
>> +// SPDX-License-Identifier: GPL-2.0
>> +// Copyright (C) 2022, Intel Corp. All rights reserved.
>> +#include <stdio.h>
>> +#include <json-c/json.h>
>> +#include <util/json.h>
>> +#include <util/util.h>
>> +#include <util/parse-options.h>
>> +#include <util/parse-configs.h>
> 
> The above two seem unnecessary.
> 
>> +#include <util/strbuf.h>
>> +#include <util/sysfs.h>
> 
> Same with this.
> 
>> +#include <ccan/list/list.h>
>> +#include <ndctl/ndctl.h>
>> +#include <ndctl/libndctl.h>
> 
> Are the ndctl includes needed for anything?
> 
>> +#include <sys/epoll.h>
>> +#include <sys/stat.h>
> 
> These two look unused too.
> 
>> +#include <libcxl.h>
> 
> This could be dropped too.

Will drop all the unnecessary headers. Copied them from ndctl monitor.

> 
>> +#include <uuid/uuid.h>
>> +#include <traceevent/event-parse.h>
>> +#include "json.h"
>> +#include "event_trace.h"
>> +
>> +#define _GNU_SOURCE
>> +#include <string.h>
>> +
>> +static struct json_object *num_to_json(void *num, int elem_size, unsigned long flags)
>> +{
>> +       bool sign = flags & TEP_FIELD_IS_SIGNED;
>> +       int64_t val = 0;
>> +
>> +       /* special case 64 bit as the call depends on sign */
>> +       if (elem_size == 8) {
>> +               if (sign)
>> +                       return json_object_new_int64(*(int64_t *)num);
>> +               else
>> +                       return json_object_new_uint64(*(uint64_t *)num);
>> +       }
>> +
>> +       /* All others fit in a signed 64 bit */
>> +       switch (elem_size) {
>> +       case 1:
>> +               if (sign)
>> +                       val = *(int8_t *)num;
>> +               else
>> +                       val = *(uint8_t *)num;
>> +               break;
>> +       case 2:
>> +               if (sign)
>> +                       val = *(int16_t *)num;
>> +               else
>> +                       val = *(uint16_t *)num;
>> +               break;
>> +       case 4:
>> +               if (sign)
>> +                       val = *(int32_t *)num;
>> +               else
>> +                       val = *(uint32_t *)num;
>> +               break;
>> +       default:
>> +               /*
>> +                * Odd sizes are converted in the kernel to one of the above.
>> +                * It is an error to see them here.
>> +                */
>> +               return NULL;
>> +       }
>> +
>> +       return json_object_new_int64(val);
>> +}
>> +
>> +static int cxl_event_to_json_callback(struct tep_event *event,
>> +               struct tep_record *record, struct list_head *jlist_head)
> 
> Instead of the old double-tab style continuations, we added a .clang-
> format to ndctl, which will format this slightly differently (matching
> the continuation to the first char after the opening parens).

Will fix.

> 
> Also, is 'callback' in the name useful? I'd consider dropping it -
> 'cxl_event_to_json' conveys just as much information about what it
> does.

ok

> 
>> +{
>> +       struct tep_format_field **fields;
>> +       struct json_object *jevent, *jobj, *jarray;
> 
> Minor/optional nit, but these look nice and clean in reverse-christmas
> tree used elsewhere :)
> 
>> +       struct jlist_node *jnode;
>> +       int i, j, rc = 0;
>> +
>> +       jnode = malloc(sizeof(*jnode));
>> +       if (!jnode)
>> +               return -ENOMEM;
>> +
>> +       jevent = json_object_new_object();
>> +       if (!jevent) {
>> +               rc = -ENOMEM;
>> +               goto err_jevent;
> 
> Also minor, but the label should probably be called err_free or
> something since you goto it before jevent needs to be freed.

Renaming first "err_jevent" to "err_jnode" and renaming "err" to 
"err_jevent".

> 
>> +       }
>> +       jnode->jobj = jevent;
>> +
>> +       fields = tep_event_fields(event);
>> +       if (!fields) {
>> +               rc = -ENOENT;
>> +               goto err;
>> +       }
>> +
>> +       jobj = json_object_new_string(event->system);
>> +       if (!jobj) {
>> +               rc = -ENOMEM;
>> +               goto err;
>> +       }
>> +       json_object_object_add(jevent, "system", jobj);
>> +
>> +       jobj = json_object_new_string(event->name);
>> +       if (!jobj) {
>> +               rc = -ENOMEM;
>> +               goto err;
>> +       }
>> +       json_object_object_add(jevent, "event", jobj);
>> +
>> +       jobj = json_object_new_uint64(record->ts);
>> +       if (!jobj) {
>> +               rc = -ENOMEM;
>> +               goto err;
>> +       }
>> +       json_object_object_add(jevent, "timestamp", jobj);
>> +
>> +       for (i = 0; fields[i]; i++) {
>> +               struct tep_format_field *f = fields[i];
>> +               int len;
>> +
>> +               if (f->flags & TEP_FIELD_IS_STRING) {
>> +                       char *str;
>> +
>> +                       str = tep_get_field_raw(NULL, event, f->name, record, &len, 0);
>> +                       if (!str)
>> +                               continue;
>> +
>> +                       jobj = json_object_new_string(str);
>> +                       if (!jobj) {
>> +                               rc = -ENOMEM;
>> +                               goto err;
>> +                       }
>> +
>> +                       json_object_object_add(jevent, f->name, jobj);
>> +               } else if (f->flags & TEP_FIELD_IS_ARRAY) {
>> +                       unsigned char *data;
>> +                       int chunks;
>> +
>> +                       data = tep_get_field_raw(NULL, event, f->name, record, &len, 0);
>> +                       if (!data)
>> +                               continue;
>> +
>> +                       jarray = json_object_new_array();
>> +                       if (!jarray) {
>> +                               rc = -ENOMEM;
>> +                               goto err;
>> +                       }
>> +
>> +                       chunks = f->size / f->elementsize;
>> +                       for (j = 0; j < chunks; j++) {
>> +                               jobj = num_to_json(data, f->elementsize, f->flags);
>> +                               if (!jobj) {
>> +                                       json_object_put(jarray);
>> +                                       return -ENOMEM;
>> +                               }
>> +                               json_object_array_add(jarray, jobj);
>> +                               data += f->elementsize;
>> +                       }
>> +
>> +                       json_object_object_add(jevent, f->name, jarray);
>> +               } else { /* single number */
>> +                       unsigned char *data;
>> +                       char *tmp;
>> +
>> +                       data = tep_get_field_raw(NULL, event, f->name, record, &len, 0);
>> +                       if (!data)
>> +                               continue;
>> +
>> +                       /* check to see if we have a UUID */
>> +                       tmp = strcasestr(f->type, "uuid_t");
>> +                       if (tmp) {
>> +                               char uuid[SYSFS_ATTR_SIZE];
> 
> Does this need to be SYSFS_ATTR_SIZE? Looks like historically we've
> just created such UUID buffers to be buf[40]. I think the sysfs size is
> 4096.
> 

Ok will change to 40.

>> +
>> +                               uuid_unparse(data, uuid);
>> +                               jobj = json_object_new_string(uuid);
>> +                               if (!jobj) {
>> +                                       rc = -ENOMEM;
>> +                                       goto err;
>> +                               }
>> +
>> +                               json_object_object_add(jevent, f->name, jobj);
>> +                               continue;
>> +                       }
>> +
>> +                       jobj = num_to_json(data, f->elementsize, f->flags);
>> +                       if (!jobj) {
>> +                               rc = -ENOMEM;
>> +                               goto err;
>> +                       }
>> +
>> +                       json_object_object_add(jevent, f->name, jobj);
>> +               }
>> +       }
>> +
>> +       list_add_tail(jlist_head, &jnode->list);
>> +       return 0;
>> +
>> +err:
>> +       json_object_put(jevent);
>> +err_jevent:
>> +       free(jnode);
>> +       return rc;
>> +}
>> diff --git a/cxl/event_trace.h b/cxl/event_trace.h
>> new file mode 100644
>> index 000000000000..00975a0b5680
>> --- /dev/null
>> +++ b/cxl/event_trace.h
>> @@ -0,0 +1,14 @@
>> +/* SPDX-License-Identifier: GPL-2.0 */
>> +/* Copyright (C) 2022 Intel Corporation. All rights reserved. */
>> +#ifndef __CXL_EVENT_TRACE_H__
>> +#define __CXL_EVENT_TRACE_H__
>> +
>> +#include <json-c/json.h>
>> +#include <ccan/list/list.h>
>> +
>> +struct jlist_node {
>> +       struct json_object *jobj;
>> +       struct list_node list;
>> +};
>> +
>> +#endif
>> diff --git a/cxl/meson.build b/cxl/meson.build
>> index f2474aaa6e2e..8c7733431613 100644
>> --- a/cxl/meson.build
>> +++ b/cxl/meson.build
>> @@ -7,6 +7,7 @@ cxl_src = [
>>     'memdev.c',
>>     'json.c',
>>     'filter.c',
>> +  'event_trace.c',
>>   ]
>>   
>>   cxl_tool = executable('cxl',
>> @@ -19,6 +20,7 @@ cxl_tool = executable('cxl',
>>       kmod,
>>       json,
>>       versiondep,
>> +    traceevent,
>>     ],
>>     install : true,
>>     install_dir : rootbindir,
>> diff --git a/meson.build b/meson.build
>> index 20a646d135c7..f611e0bdd7f3 100644
>> --- a/meson.build
>> +++ b/meson.build
>> @@ -142,6 +142,7 @@ kmod = dependency('libkmod')
>>   libudev = dependency('libudev')
>>   uuid = dependency('uuid')
>>   json = dependency('json-c')
>> +traceevent = dependency('libtraceevent')
>>   if get_option('docs').enabled()
>>     if get_option('asciidoctor').enabled()
>>       asciidoc = find_program('asciidoctor', required : true)
>>
>>
> 

Re: [PATCH v4 02/10] cxl: add helper to parse through all current events

[Dave Jiang]

On 11/8/2022 3:45 PM, Verma, Vishal L wrote:
> On Tue, 2022-11-08 at 11:29 -0700, Dave Jiang wrote:
>> Add common function to iterate through and extract the events in the
>> current trace buffer. The function uses tracefs_iterate_raw_events() from
>> libtracefs to go through all the events loaded into a tep_handle. A
>> callback is provided to the API call in order to parse the event. For cxl
>> monitor, an array of interested "systems" is provided in order to filter
> 
> I couldn't tell what a 'system' means here - maybe clarify that?

It's an trace event term. In this case, the system would be "cxl". I'll 
clarify. It's trace event's category.

> 
>> for the interested events.
> 
> s/interested events/events of interest/ ?
> 
>>
>> Tested-by: Alison Schofield <alison.schofield@intel.com>
>> Signed-off-by: Dave Jiang <dave.jiang@intel.com>
>> ---
>>   cxl/event_trace.c |   36 ++++++++++++++++++++++++++++++++++++
>>   cxl/event_trace.h |   10 ++++++++++
>>   cxl/meson.build   |    1 +
>>   meson.build       |    2 ++
>>   4 files changed, 49 insertions(+)
>>
>> diff --git a/cxl/event_trace.c b/cxl/event_trace.c
>> index 1b1b037e48bf..4667044e4a66 100644
>> --- a/cxl/event_trace.c
>> +++ b/cxl/event_trace.c
>> @@ -16,6 +16,7 @@
>>   #include <libcxl.h>
>>   #include <uuid/uuid.h>
>>   #include <traceevent/event-parse.h>
>> +#include <tracefs/tracefs.h>
>>   #include "json.h"
>>   #include "event_trace.h"
>>   
>> @@ -199,3 +200,38 @@ err_jevent:
>>          free(jnode);
>>          return rc;
>>   }
>> +
>> +static int cxl_event_parse_cb(struct tep_event *event, struct tep_record *record,
>> +               int cpu, void *ctx)
> 
> What does the _cb mean? I couldn't tell from what it's parsing what it
> stands for - might be better to expand it?

callback. I can just drop that.

> 
>> +{
>> +       struct event_ctx *event_ctx = (struct event_ctx *)ctx;
>> +
>> +       /* Filter out all the events that the caller isn't interested in. */
>> +       if (strcmp(event->system, event_ctx->system) != 0)
>> +               return 0;
>> +
>> +       if (event_ctx->event_name) {
>> +               if (strcmp(event->name, event_ctx->event_name) != 0)
>> +                       return 0;
>> +       }
>> +
>> +       if (event_ctx->parse_event)
>> +               return event_ctx->parse_event(event, record, &event_ctx->jlist_head);
>> +
>> +       return cxl_event_to_json_callback(event, record, &event_ctx->jlist_head);
>> +}
>> +
>> +int cxl_parse_events(struct tracefs_instance *inst, struct event_ctx *ectx)
>> +{
>> +       struct tep_handle *tep;
>> +       int rc;
>> +
>> +       tep = tracefs_local_events(NULL);
>> +       if (!tep)
>> +               return -ENOMEM;
>> +
>> +       rc = tracefs_iterate_raw_events(tep, inst, NULL, 0,
>> +                       cxl_event_parse_cb, ectx);
>> +       tep_free(tep);
>> +       return rc;
>> +}
>> diff --git a/cxl/event_trace.h b/cxl/event_trace.h
>> index 00975a0b5680..582882c1eb35 100644
>> --- a/cxl/event_trace.h
>> +++ b/cxl/event_trace.h
>> @@ -11,4 +11,14 @@ struct jlist_node {
>>          struct list_node list;
>>   };
>>   
>> +struct event_ctx {
>> +       const char *system;
>> +       struct list_head jlist_head;
>> +       const char *event_name;                                 /* optional */
>> +       int (*parse_event)(struct tep_event *event, struct tep_record *record,
>> +                          struct list_head *jlist_head);       /* optional */
>> +};
>> +
>> +int cxl_parse_events(struct tracefs_instance *inst, struct event_ctx *ectx);
>> +
>>   #endif
>> diff --git a/cxl/meson.build b/cxl/meson.build
>> index 8c7733431613..c59876262e76 100644
>> --- a/cxl/meson.build
>> +++ b/cxl/meson.build
>> @@ -21,6 +21,7 @@ cxl_tool = executable('cxl',
>>       json,
>>       versiondep,
>>       traceevent,
>> +    tracefs,
>>     ],
>>     install : true,
>>     install_dir : rootbindir,
>> diff --git a/meson.build b/meson.build
>> index f611e0bdd7f3..c204c8ac52de 100644
>> --- a/meson.build
>> +++ b/meson.build
>> @@ -143,6 +143,8 @@ libudev = dependency('libudev')
>>   uuid = dependency('uuid')
>>   json = dependency('json-c')
>>   traceevent = dependency('libtraceevent')
>> +tracefs = dependency('libtracefs')
>> +
>>   if get_option('docs').enabled()
>>     if get_option('asciidoctor').enabled()
>>       asciidoc = find_program('asciidoctor', required : true)
>>
>>
> 

Re: [PATCH v4 08/10] cxl: add an optional pid check to event parsing

[Dave Jiang]

On 11/8/2022 4:48 PM, Verma, Vishal L wrote:
> On Tue, 2022-11-08 at 11:30 -0700, Dave Jiang wrote:
>> From: Alison Schofield <alison.schofield@intel.com>
>>
>> When parsing CXL events, callers may only be interested in events
>> that originate from the current process. Introduce an optional
>> argument to the event trace context: event_pid. When event_pid is
>> present, only include events with a matching pid in the returned
>> JSON list. It is not a failure to see other, non matching results.
>> Simply skip those.
>>
>> The initial use case for this is the listing of media errors,
>> where only the media-errors requested by this process are wanted.
>>
>> Signed-off-by: Alison Schofield <alison.schofield@intel.com>
>> Signed-off-by: Dave Jiang <dave.jiang@intel.com>
>> ---
>>   cxl/event_trace.c |    5 +++++
>>   cxl/event_trace.h |    1 +
>>   2 files changed, 6 insertions(+)
> 
> I might be missing something - but this patch is added at then end,
> without subsequently using the event_pid in cxl-monitor? So why not
> leave this to be part of the media errors patches?

Alison, you want to move this to your series?

> 
>>
>> diff --git a/cxl/event_trace.c b/cxl/event_trace.c
>> index 490c30e1dbfc..89c9c2db26a3 100644
>> --- a/cxl/event_trace.c
>> +++ b/cxl/event_trace.c
>> @@ -215,6 +215,11 @@ static int cxl_event_parse_cb(struct tep_event *event, struct tep_record *record
>>                          return 0;
>>          }
>>   
>> +       if (event_ctx->event_pid) {
>> +               if (event_ctx->event_pid != tep_data_pid(event->tep, record))
>> +                       return 0;
>> +       }
>> +
>>          if (event_ctx->parse_event)
>>                  return event_ctx->parse_event(event, record, &event_ctx->jlist_head);
>>   
>> diff --git a/cxl/event_trace.h b/cxl/event_trace.h
>> index 89e98cafb320..e72b4347175e 100644
>> --- a/cxl/event_trace.h
>> +++ b/cxl/event_trace.h
>> @@ -15,6 +15,7 @@ struct event_ctx {
>>          const char *system;
>>          struct list_head jlist_head;
>>          const char *event_name;                                 /* optional */
>> +       int event_pid;                                          /* optional */
>>          int (*parse_event)(struct tep_event *event, struct tep_record *record,
>>                             struct list_head *jlist_head);       /* optional */
>>   };
>>
>>
> 

Re: [PATCH v4 05/10] cxl: add monitor function for event trace events

[Steven Rostedt]

On Tue, 08 Nov 2022 11:30:16 -0700
Dave Jiang <dave.jiang@intel.com> wrote:

> Add function that creates an event trace instance and utilize the cxl event
> trace common functions to extract interested events from the trace buffer.
> The monitoring function will pend on an epoll fd and wait for new events
> to appear in the trace buffer.
> 
> Signed-off-by: Dave Jiang <dave.jiang@intel.com>
> ---
>  cxl/meson.build |    1 
>  cxl/monitor.c   |  140 +++++++++++++++++++++++++++++++++++++++++++++++++++++++
>  2 files changed, 141 insertions(+)
>  create mode 100644 cxl/monitor.c
> 
> diff --git a/cxl/meson.build b/cxl/meson.build
> index c59876262e76..eb8b2b1070ed 100644
> --- a/cxl/meson.build
> +++ b/cxl/meson.build
> @@ -8,6 +8,7 @@ cxl_src = [
>    'json.c',
>    'filter.c',
>    'event_trace.c',
> +  'monitor.c',
>  ]
>  
>  cxl_tool = executable('cxl',
> diff --git a/cxl/monitor.c b/cxl/monitor.c
> new file mode 100644
> index 000000000000..c3f7e3639ec0
> --- /dev/null
> +++ b/cxl/monitor.c
> @@ -0,0 +1,140 @@
> +// SPDX-License-Identifier: GPL-2.0
> +// Copyright (C) 2022, Intel Corp. All rights reserved.
> +/* Some bits copied from ndctl monitor code */
> +#include <stdio.h>
> +#include <unistd.h>
> +#include <errno.h>
> +#include <json-c/json.h>
> +#include <libgen.h>
> +#include <time.h>
> +#include <dirent.h>
> +#include <ccan/list/list.h>
> +#include <util/json.h>
> +#include <util/util.h>
> +#include <util/parse-options.h>
> +#include <util/parse-configs.h>
> +#include <util/strbuf.h>
> +#include <sys/epoll.h>
> +#include <sys/stat.h>
> +#include <traceevent/event-parse.h>
> +#include <tracefs/tracefs.h>
> +#include <cxl/libcxl.h>
> +
> +/* reuse the core log helpers for the monitor logger */
> +#ifndef ENABLE_LOGGING
> +#define ENABLE_LOGGING
> +#endif
> +#ifndef ENABLE_DEBUG
> +#define ENABLE_DEBUG
> +#endif
> +#include <util/log.h>
> +
> +#include "event_trace.h"
> +
> +static const char *cxl_system = "cxl";
> +
> +static struct monitor {
> +	struct log_ctx ctx;
> +	FILE *log_file;
> +	bool human;
> +} monitor;
> +
> +static int monitor_event(struct cxl_ctx *ctx)
> +{
> +	int fd, epollfd, rc = 0, timeout = -1;
> +	struct epoll_event ev, *events;
> +	struct tracefs_instance *inst;
> +	struct event_ctx ectx;
> +	int jflag;
> +
> +	events = calloc(1, sizeof(struct epoll_event));
> +	if (!events) {
> +		err(&monitor, "alloc for events error\n");
> +		return -ENOMEM;
> +	}
> +
> +	epollfd = epoll_create1(0);
> +	if (epollfd == -1) {
> +		rc = -errno;
> +		err(&monitor, "epoll_create1() error: %d\n", rc);
> +		goto epoll_err;
> +	}
> +
> +	inst = tracefs_instance_create("cxl_monitor");
> +	if (!inst) {
> +		rc = -errno;
> +		err(&monitor, "tracefs_instance_create( failed: %d\n", rc);
> +		goto inst_err;
> +	}
> +
> +	fd = tracefs_instance_file_open(inst, "trace_pipe", -1);

FYI, libtracefs now has an API to read the raw trace file directly.

  https://www.trace-cmd.org/Documentation/libtracefs-doc/libtracefs-cpu.html

as well iterate over the live stream:

  https://www.trace-cmd.org/Documentation/libtracefs-doc/libtracefs-iterator.html

-- Steve

> +	if (fd < 0) {
> +		rc = fd;
> +		err(&monitor, "tracefs_instance_file_open() err: %d\n", rc);
> +		goto inst_file_err;
> +	}
> +
> +	memset(&ev, 0, sizeof(ev));
> +	ev.events = EPOLLIN;
> +	ev.data.fd = fd;
> +
> +	if (epoll_ctl(epollfd, EPOLL_CTL_ADD, fd, &ev) != 0) {
> +		rc = -errno;
> +		err(&monitor, "epoll_ctl() error: %d\n", rc);
> +		goto epoll_ctl_err;
> +	}
> +
> +	rc = cxl_event_tracing_enable(inst, cxl_system, NULL);
> +	if (rc < 0) {
> +		err(&monitor, "cxl_trace_event_enable() failed: %d\n", rc);
> +		goto event_en_err;
> +	}
> +
> +	memset(&ectx, 0, sizeof(ectx));
> +	ectx.system = cxl_system;
> +	if (monitor.human)
> +		jflag = JSON_C_TO_STRING_PRETTY;
> +	else
> +		jflag = JSON_C_TO_STRING_PLAIN;
> +
> +	while (1) {
> +		struct jlist_node *jnode, *next;
> +
> +		rc = epoll_wait(epollfd, events, 1, timeout);
> +		if (rc < 0) {
> +			rc = -errno;
> +			if (errno != EINTR)
> +				err(&monitor, "epoll_wait error: %d\n", -errno);
> +			break;
> +		}
> +
> +		list_head_init(&ectx.jlist_head);
> +		rc = cxl_parse_events(inst, &ectx);
> +		if (rc < 0)
> +			goto parse_err;
> +
> +		if (list_empty(&ectx.jlist_head))
> +			continue;
> +
> +		list_for_each_safe(&ectx.jlist_head, jnode, next, list) {
> +			notice(&monitor, "%s\n",
> +				json_object_to_json_string_ext(jnode->jobj, jflag));
> +			list_del(&jnode->list);
> +			json_object_put(jnode->jobj);
> +			free(jnode);
> +		}
> +	}
> +
> +parse_err:
> +	rc = cxl_event_tracing_disable(inst);
> +event_en_err:
> +epoll_ctl_err:
> +	close(fd);
> +inst_file_err:
> +	tracefs_instance_free(inst);
> +inst_err:
> +	close(epollfd);
> +epoll_err:
> +	free(events);
> +	return rc;
> +}
> 

Re: [PATCH v4 05/10] cxl: add monitor function for event trace events

[Dave Jiang]

On 11/17/2022 11:37 AM, Steven Rostedt wrote:
> On Tue, 08 Nov 2022 11:30:16 -0700
> Dave Jiang <dave.jiang@intel.com> wrote:
> 
>> Add function that creates an event trace instance and utilize the cxl event
>> trace common functions to extract interested events from the trace buffer.
>> The monitoring function will pend on an epoll fd and wait for new events
>> to appear in the trace buffer.
>>
>> Signed-off-by: Dave Jiang <dave.jiang@intel.com>
>> ---
>>   cxl/meson.build |    1
>>   cxl/monitor.c   |  140 +++++++++++++++++++++++++++++++++++++++++++++++++++++++
>>   2 files changed, 141 insertions(+)
>>   create mode 100644 cxl/monitor.c
>>
>> diff --git a/cxl/meson.build b/cxl/meson.build
>> index c59876262e76..eb8b2b1070ed 100644
>> --- a/cxl/meson.build
>> +++ b/cxl/meson.build
>> @@ -8,6 +8,7 @@ cxl_src = [
>>     'json.c',
>>     'filter.c',
>>     'event_trace.c',
>> +  'monitor.c',
>>   ]
>>   
>>   cxl_tool = executable('cxl',
>> diff --git a/cxl/monitor.c b/cxl/monitor.c
>> new file mode 100644
>> index 000000000000..c3f7e3639ec0
>> --- /dev/null
>> +++ b/cxl/monitor.c
>> @@ -0,0 +1,140 @@
>> +// SPDX-License-Identifier: GPL-2.0
>> +// Copyright (C) 2022, Intel Corp. All rights reserved.
>> +/* Some bits copied from ndctl monitor code */
>> +#include <stdio.h>
>> +#include <unistd.h>
>> +#include <errno.h>
>> +#include <json-c/json.h>
>> +#include <libgen.h>
>> +#include <time.h>
>> +#include <dirent.h>
>> +#include <ccan/list/list.h>
>> +#include <util/json.h>
>> +#include <util/util.h>
>> +#include <util/parse-options.h>
>> +#include <util/parse-configs.h>
>> +#include <util/strbuf.h>
>> +#include <sys/epoll.h>
>> +#include <sys/stat.h>
>> +#include <traceevent/event-parse.h>
>> +#include <tracefs/tracefs.h>
>> +#include <cxl/libcxl.h>
>> +
>> +/* reuse the core log helpers for the monitor logger */
>> +#ifndef ENABLE_LOGGING
>> +#define ENABLE_LOGGING
>> +#endif
>> +#ifndef ENABLE_DEBUG
>> +#define ENABLE_DEBUG
>> +#endif
>> +#include <util/log.h>
>> +
>> +#include "event_trace.h"
>> +
>> +static const char *cxl_system = "cxl";
>> +
>> +static struct monitor {
>> +	struct log_ctx ctx;
>> +	FILE *log_file;
>> +	bool human;
>> +} monitor;
>> +
>> +static int monitor_event(struct cxl_ctx *ctx)
>> +{
>> +	int fd, epollfd, rc = 0, timeout = -1;
>> +	struct epoll_event ev, *events;
>> +	struct tracefs_instance *inst;
>> +	struct event_ctx ectx;
>> +	int jflag;
>> +
>> +	events = calloc(1, sizeof(struct epoll_event));
>> +	if (!events) {
>> +		err(&monitor, "alloc for events error\n");
>> +		return -ENOMEM;
>> +	}
>> +
>> +	epollfd = epoll_create1(0);
>> +	if (epollfd == -1) {
>> +		rc = -errno;
>> +		err(&monitor, "epoll_create1() error: %d\n", rc);
>> +		goto epoll_err;
>> +	}
>> +
>> +	inst = tracefs_instance_create("cxl_monitor");
>> +	if (!inst) {
>> +		rc = -errno;
>> +		err(&monitor, "tracefs_instance_create( failed: %d\n", rc);
>> +		goto inst_err;
>> +	}
>> +
>> +	fd = tracefs_instance_file_open(inst, "trace_pipe", -1);
> 
> FYI, libtracefs now has an API to read the raw trace file directly.
> 
>    https://www.trace-cmd.org/Documentation/libtracefs-doc/libtracefs-cpu.html
> 
> as well iterate over the live stream:
> 
>    https://www.trace-cmd.org/Documentation/libtracefs-doc/libtracefs-iterator.html

Hi Steve,
After looking those over, I'm uncertain how the new APIs would apply 
here. I'm only using fd to the trace_pipe for epoll notification of new 
events for the instance. Otherwise I'm using 
tracefs_iterate_raw_events() to retrieve and parse the events.

> 
> -- Steve
> 
>> +	if (fd < 0) {
>> +		rc = fd;
>> +		err(&monitor, "tracefs_instance_file_open() err: %d\n", rc);
>> +		goto inst_file_err;
>> +	}
>> +
>> +	memset(&ev, 0, sizeof(ev));
>> +	ev.events = EPOLLIN;
>> +	ev.data.fd = fd;
>> +
>> +	if (epoll_ctl(epollfd, EPOLL_CTL_ADD, fd, &ev) != 0) {
>> +		rc = -errno;
>> +		err(&monitor, "epoll_ctl() error: %d\n", rc);
>> +		goto epoll_ctl_err;
>> +	}
>> +
>> +	rc = cxl_event_tracing_enable(inst, cxl_system, NULL);
>> +	if (rc < 0) {
>> +		err(&monitor, "cxl_trace_event_enable() failed: %d\n", rc);
>> +		goto event_en_err;
>> +	}
>> +
>> +	memset(&ectx, 0, sizeof(ectx));
>> +	ectx.system = cxl_system;
>> +	if (monitor.human)
>> +		jflag = JSON_C_TO_STRING_PRETTY;
>> +	else
>> +		jflag = JSON_C_TO_STRING_PLAIN;
>> +
>> +	while (1) {
>> +		struct jlist_node *jnode, *next;
>> +
>> +		rc = epoll_wait(epollfd, events, 1, timeout);
>> +		if (rc < 0) {
>> +			rc = -errno;
>> +			if (errno != EINTR)
>> +				err(&monitor, "epoll_wait error: %d\n", -errno);
>> +			break;
>> +		}
>> +
>> +		list_head_init(&ectx.jlist_head);
>> +		rc = cxl_parse_events(inst, &ectx);
>> +		if (rc < 0)
>> +			goto parse_err;
>> +
>> +		if (list_empty(&ectx.jlist_head))
>> +			continue;
>> +
>> +		list_for_each_safe(&ectx.jlist_head, jnode, next, list) {
>> +			notice(&monitor, "%s\n",
>> +				json_object_to_json_string_ext(jnode->jobj, jflag));
>> +			list_del(&jnode->list);
>> +			json_object_put(jnode->jobj);
>> +			free(jnode);
>> +		}
>> +	}
>> +
>> +parse_err:
>> +	rc = cxl_event_tracing_disable(inst);
>> +event_en_err:
>> +epoll_ctl_err:
>> +	close(fd);
>> +inst_file_err:
>> +	tracefs_instance_free(inst);
>> +inst_err:
>> +	close(epollfd);
>> +epoll_err:
>> +	free(events);
>> +	return rc;
>> +}
>>
> 

Re: [PATCH v4 05/10] cxl: add monitor function for event trace events

[Steven Rostedt]

On Thu, 17 Nov 2022 13:29:42 -0700
Dave Jiang <dave.jiang@intel.com> wrote:

> > as well iterate over the live stream:
> > 
> >    https://www.trace-cmd.org/Documentation/libtracefs-doc/libtracefs-iterator.html  
> 
> Hi Steve,
> After looking those over, I'm uncertain how the new APIs would apply 
> here. I'm only using fd to the trace_pipe for epoll notification of new 
> events for the instance. Otherwise I'm using 
> tracefs_iterate_raw_events() to retrieve and parse the events.

Ah sorry, I didn't look farther to see how it was being used.

And I plan on adding a tracefs_wait(instance, percentage) function that
will do just that, but haven't implemented it yet.

-- Steve

Re: [PATCH v4 05/10] cxl: add monitor function for event trace events

[Dave Jiang]

On 11/17/2022 1:33 PM, Steven Rostedt wrote:
> On Thu, 17 Nov 2022 13:29:42 -0700
> Dave Jiang <dave.jiang@intel.com> wrote:
> 
>>> as well iterate over the live stream:
>>>
>>>     https://www.trace-cmd.org/Documentation/libtracefs-doc/libtracefs-iterator.html
>>
>> Hi Steve,
>> After looking those over, I'm uncertain how the new APIs would apply
>> here. I'm only using fd to the trace_pipe for epoll notification of new
>> events for the instance. Otherwise I'm using
>> tracefs_iterate_raw_events() to retrieve and parse the events.
> 
> Ah sorry, I didn't look farther to see how it was being used.
> 
> And I plan on adding a tracefs_wait(instance, percentage) function that
> will do just that, but haven't implemented it yet.

Ah great! Looking forward to convert the code to use that in the future.

> 
> -- Steve