From: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Date: Mon, 30 Jan 2012 15:30:05 +0000 (-0500)
Subject: clock: read bootid as clock monotonic ID
X-Git-Tag: v2.0-pre12~7
X-Git-Url: http://git.lttng.org/?p=lttng-modules.git;a=commitdiff_plain;h=a82c63f10514ca43282498ea4fdee3908576528a

clock: read bootid as clock monotonic ID

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
---

diff --git a/Makefile b/Makefile
index ad2ff5a7..2cfc6901 100644
--- a/Makefile
+++ b/Makefile
@@ -19,7 +19,8 @@ lttng-tracer-objs :=  lttng-events.o lttng-abi.o \
 			lttng-context-prio.o lttng-context-nice.o \
 			lttng-context-vpid.o lttng-context-tid.o \
 			lttng-context-vtid.o lttng-context-ppid.o \
-			lttng-context-vppid.o lttng-calibrate.o
+			lttng-context-vppid.o lttng-calibrate.o \
+			wrapper/random.o
 
 ifneq ($(CONFIG_HAVE_SYSCALL_TRACEPOINTS),)
 lttng-tracer-objs += lttng-syscalls.o
diff --git a/lttng-events.c b/lttng-events.c
index 6dd3ba4e..c25d4449 100644
--- a/lttng-events.c
+++ b/lttng-events.c
@@ -16,6 +16,7 @@
 #include <linux/jiffies.h>
 #include "wrapper/uuid.h"
 #include "wrapper/vmalloc.h"	/* for wrapper_vmalloc_sync_all() */
+#include "wrapper/random.h"
 #include "lttng-events.h"
 #include "lttng-tracer.h"
 
@@ -881,7 +882,7 @@ static
 int _lttng_session_metadata_statedump(struct lttng_session *session)
 {
 	unsigned char *uuid_c = session->uuid.b;
-	unsigned char uuid_s[37];
+	unsigned char uuid_s[37], clock_uuid_s[BOOT_ID_LEN];
 	struct lttng_channel *chan;
 	struct lttng_event *event;
 	int ret = 0;
@@ -939,15 +940,27 @@ int _lttng_session_metadata_statedump(struct lttng_session *session)
 
 	ret = lttng_metadata_printf(session,
 		"clock {\n"
-		"	name = %s;\n"
-		"	uuid = %s;\n"
+		"	name = %s;\n",
+		"monotonic"
+		);
+	if (ret)
+		goto end;
+
+	if (!trace_clock_uuid(clock_uuid_s)) {
+		ret = lttng_metadata_printf(session,
+			"	uuid = %s;\n",
+			clock_uuid_s
+			);
+		if (ret)
+			goto end;
+	}
+
+	ret = lttng_metadata_printf(session,
 		"	description = \"Monotonic Clock\";\n"
 		"	freq = %llu; /* Frequency, in Hz */\n"
 		"	/* clock value offset from Epoch is: offset * (1/freq) */\n"
 		"	offset = %llu;\n"
 		"};\n\n",
-		"monotonic",
-		trace_clock_uuid(),
 		(unsigned long long) trace_clock_freq(),
 		(unsigned long long) measure_clock_offset()
 		);
diff --git a/wrapper/random.c b/wrapper/random.c
new file mode 100644
index 00000000..da8cb176
--- /dev/null
+++ b/wrapper/random.c
@@ -0,0 +1,63 @@
+/*
+ * Copyright (C) 2011 Mathieu Desnoyers (mathieu.desnoyers@efficios.com)
+ *
+ * wrapper around bootid read. Using KALLSYMS to get its address when
+ * available, else we need to have a kernel that exports this function to GPL
+ * modules.
+ *
+ * Dual LGPL v2.1/GPL v2 license.
+ */
+
+/* boot_id depends on sysctl */
+#if defined(CONFIG_SYSCTL)
+
+#include <linux/fs.h>
+#include <linux/file.h>
+#include <linux/sched.h>
+#include <linux/uaccess.h>
+#include "random.h"
+
+/*
+ * Returns string boot id.
+ */
+int wrapper_get_bootid(char *bootid)
+{
+	struct file *file;
+	int ret;
+	ssize_t len;
+	mm_segment_t old_fs;
+
+	file = filp_open("/proc/sys/kernel/random/boot_id", O_RDONLY, 0);
+	if (IS_ERR(file))
+		return PTR_ERR(file);
+
+	old_fs = get_fs();
+	set_fs(KERNEL_DS);
+
+	if (!file->f_op || !file->f_op->read) {
+		ret = -EINVAL;
+		goto end;
+	}
+
+	len = file->f_op->read(file, bootid, BOOT_ID_LEN - 1, &file->f_pos);
+	if (len != BOOT_ID_LEN - 1) {
+		ret = -EINVAL;
+		goto end;
+	}
+	
+	bootid[BOOT_ID_LEN - 1] = '\0';
+	ret = 0;
+end:
+	set_fs(old_fs);
+	filp_close(file, current->files);
+	return ret;
+}
+
+#else
+
+int wrapper_get_bootid(char *bootid)
+{
+	return -ENOSYS;
+}
+
+#endif
diff --git a/wrapper/random.h b/wrapper/random.h
new file mode 100644
index 00000000..30a14d18
--- /dev/null
+++ b/wrapper/random.h
@@ -0,0 +1,18 @@
+#ifndef _LTTNG_WRAPPER_RANDOM_H
+#define _LTTNG_WRAPPER_RANDOM_H
+
+/*
+ * Copyright (C) 2011 Mathieu Desnoyers (mathieu.desnoyers@efficios.com)
+ *
+ * wrapper around bootid read. Using KALLSYMS to get its address when
+ * available, else we need to have a kernel that exports this function to GPL
+ * modules.
+ *
+ * Dual LGPL v2.1/GPL v2 license.
+ */
+
+#define BOOT_ID_LEN	37
+
+int wrapper_get_bootid(char *bootid);
+
+#endif /* _LTTNG_WRAPPER_RANDOM_H */
diff --git a/wrapper/trace-clock.h b/wrapper/trace-clock.h
index 1140b94b..801e640e 100644
--- a/wrapper/trace-clock.h
+++ b/wrapper/trace-clock.h
@@ -18,6 +18,7 @@
 #include <linux/ktime.h>
 #include <linux/time.h>
 #include <linux/hrtimer.h>
+#include "random.h"
 
 static inline u64 trace_clock_monotonic_wrapper(void)
 {
@@ -49,9 +50,9 @@ static inline u64 trace_clock_freq(void)
 	return (u64) NSEC_PER_SEC;
 }
 
-static inline const char *trace_clock_uuid(void)
+static inline int trace_clock_uuid(char *uuid)
 {
-	return "CLOCK_MONOTONIC";
+	return wrapper_get_bootid(uuid);
 }
 
 static inline int get_trace_clock(void)