[ltt-dev] [PATCH] make lttctl select channel_root in debugfs automatically

[ltt-dev] [PATCH] make lttctl select channel_root in debugfs automatically

[Zhaolei]

Hi Mathieu,

this patch make lttctl select channel_root in debugfs automatically
 when no specify.
Applies on top of ltt-control-0.54-10102008.

Signed-off-by: Zhaolei <zhaolei at cn.fujitsu.com>
---
diff -Nur ltt-control-0.54-10102008.org/lttctl/lttctl.c ltt-control-0.54-10102008/lttctl/lttctl.c
--- ltt-control-0.54-10102008.org/lttctl/lttctl.c	2008-10-15 15:29:54.000000000 +0800
+++ ltt-control-0.54-10102008/lttctl/lttctl.c	2008-10-16 11:53:49.000000000 +0800
@@ -22,6 +22,7 @@
 #include <signal.h>
 #include <dirent.h>
 #include <string.h>
+#include <limits.h>
 #include <sys/stat.h>
 
 /* Buffer for file copy : 4k seems optimal. */
@@ -52,6 +53,7 @@
 static enum trace_mode mode = LTT_TRACE_NORMAL;
 static enum trace_ctl_op op = CTL_OP_NONE;
 static char *channel_root = NULL;
+static char channel_root_default[PATH_MAX];
 static char *trace_root = NULL;
 static char *num_threads = "1";
 
@@ -92,6 +94,26 @@
 	printf("\n");
 }
 
+int getdebugfsmntdir(char *mntdir)
+{
+	char mnt_dir[PATH_MAX];
+	char mnt_type[PATH_MAX];
+
+	FILE *fp = fopen("/proc/mounts", "r");
+	if (!fp) {
+		return EINVAL;
+	}
+
+	while (1) {
+		if (fscanf(fp, "%*s %s %s %*s %*s %*s", mnt_dir, mnt_type) <= 0) {
+			return ENOENT;
+		}
+		if (!strcmp(mnt_type, "debugfs")) {
+			strcpy(mntdir, mnt_dir);
+			return 0;
+		}
+	}
+}
 
 /* parse_arguments
  *
@@ -304,9 +326,16 @@
 			ret = EINVAL;
 		}
 		if(channel_root == NULL) {
-			printf("Please specify -l ltt_root_path with the -d option.\n");
-			printf("\n");
-			ret = EINVAL;
+			if (getdebugfsmntdir(channel_root_default) == 0) {
+				strcat(channel_root_default, "/ltt");
+				printf("No -l ltt_root_path with the -d option, using default: %s\n", channel_root_default);
+				printf("\n");
+				channel_root=channel_root_default;
+			} else {
+				printf("Please specify -l ltt_root_path with the -d option.\n");
+				printf("\n");
+				ret = EINVAL;
+			}
 		}
 	}
 

[ltt-dev] [PATCH] Make ltt_trace_start return error when trace_name not exist

[Zhaolei]

Hi Mathieu,

I find ltt_trace_start don't return error when trace_name is not exist.
So, when we use lttctl -s to start no-exist channel, it will not print
 any errormsg:
  # ls /mnt/debugfs/ltt/
  # lttctl -n zltest -s
  Linux Trace Toolkit Trace Control 0.54-10102008
  
  Controlling trace : zltest
  
  # ls /mnt/debugfs/ltt/
  #

It can be fixed by following patch, I tested patched kernel with following command:
  # ls /mnt/debugfs/ltt/
  # lttctl -n zltest -s
  Linux Trace Toolkit Trace Control 0.54-10102008
  
  Controlling trace : zltest
  
  Start Trace Error: No such file or directory
  #

Signed-off-by: Zhaolei <zhaolei at cn.fujitsu.com>
---
 ltt/ltt-tracer.c |    5 +++--
 1 files changed, 3 insertions(+), 2 deletions(-)

diff --git a/ltt/ltt-tracer.c b/ltt/ltt-tracer.c
index 0d0423d..bc8251b 100644
--- a/ltt/ltt-tracer.c
+++ b/ltt/ltt-tracer.c
@@ -641,9 +641,10 @@ static int ltt_trace_start(char *trace_name)
 	ltt_lock_traces();
 
 	trace = _ltt_trace_find(trace_name);
-	if (trace == NULL)
-		goto no_trace;
 	err = _ltt_trace_start(trace);
+	if (err) {
+		goto no_trace;
+	}
 
 	ltt_unlock_traces();
 
-- 
1.5.5.3