[ltt-dev] PATCH] Make lttcrl/lttd show error when channel not exist

[Mathieu Desnoyers]

* Zhaolei (zhaolei at cn.fujitsu.com) wrote:
> Hello, Mathieu
> 
> When run lttctl with a no-exist debugfs's channel dir,
> it don't report error:
>   # lttctl -n channel1 -d -l /no_exist -t /tmp/channel1
>   Linux Trace Toolkit Trace Control 0.54-10102008
>   
>   Controlling trace : channel1
>   
>   Linux Trace Toolkit Trace Daemon 0.54-10102008
>   
>   Reading from debugfs directory : /no_exist/channel1
>   Writing to trace directory : /tmp/channel1
> 
>   #
> 
> It is because lttd don't return error in daemon mode:
>   # lttd -d -t /tmp/channel1 -c /no_exist
>   Linux Trace Toolkit Trace Daemon 0.54-10102008
>   
>   Reading from debugfs directory : /no_exist
>   Writing to trace directory : /tmp/channel1
>   
>   # echo $?
>   0
>   #
> 
> I moved daemon() after channels_init() and make it seems fixed.
> I tested patched program and haven't found problem:
>   # lttctl -n channel1 -d -l /no_exist -t /tmp/channel1
>   Linux Trace Toolkit Trace Control 0.54-10102008
> 
>   Controlling trace : channel1
> 
>   Linux Trace Toolkit Trace Daemon 0.54-10102008
> 
>   Reading from debugfs directory : /no_exist/channel1
>   Writing to trace directory : /tmp/channel1
> 
>   /no_exist/channel1: No such file or directory
>   Trace start error
>   #
>   #
>   # lttd -d -t /tmp/channel1 -c /no_exist
>   Linux Trace Toolkit Trace Daemon 0.54-10102008
> 
>   Reading from debugfs directory : /no_exist
>   Writing to trace directory : /tmp/channel1
>   
>   /no_exist: No such file or directory
>   #
>   #
>   # lttctl -n channel1 -d -l /mnt/debugfs/ltt/ -t /tmp/channel1
>   Linux Trace Toolkit Trace Control 0.54-10102008
> 
>   Controlling trace : channel1
> 
>   Linux Trace Toolkit Trace Daemon 0.54-10102008
> 
>   Reading from debugfs directory : /mnt/debugfs/ltt//channel1
>   Writing to trace directory : /tmp/channel1
> 
>   Creating trace subdirectory /tmp/channel1
>   Adding inotify for channel /mnt/debugfs/ltt//channel1/
>   Added inotify for channel /mnt/debugfs/ltt//channel1/, wd 1
>   Channel file : /mnt/debugfs/ltt//channel1/cpu_0
>   Opening file.
>   Channel file : /mnt/debugfs/ltt//channel1/control
>   Entering channel subdirectory...
>   Creating trace subdirectory /tmp/channel1/control
>   Adding inotify for channel /mnt/debugfs/ltt//channel1/control/
>   Added inotify for channel /mnt/debugfs/ltt//channel1/control/, wd 2
>   Channel file : /mnt/debugfs/ltt//channel1/control/network_0
>   Opening file.
>   Channel file : /mnt/debugfs/ltt//channel1/control/modules_0
>   Opening file.
>   Channel file : /mnt/debugfs/ltt//channel1/control/processes_0
>   Opening file.
>   Channel file : /mnt/debugfs/ltt//channel1/control/interrupts_0
>   Opening file.
>   Channel file : /mnt/debugfs/ltt//channel1/control/metadata_0
>   Opening file.
>   #
> 
> Cound you review it?
> 
> Btw, this patch will make lttctl and lttv show more detail message, is it necessary to cut them?
> 

Good idea. I think it would be good to add a "-v" (verbose) option to
lttd. Could you resubmit a patch that includes this change ?

Thanks,

Mathieu

> Signed-off-by: Zhao Lei <zhaolei at cn.fujitsu.com>
> ---
> diff -Nur ltt-control-0.54-10102008.org/lttd/lttd.c ltt-control-0.54-10102008/lttd/lttd.c
> --- ltt-control-0.54-10102008.org/lttd/lttd.c	2008-10-15 15:29:54.000000000 +0800
> +++ ltt-control-0.54-10102008/lttd/lttd.c	2008-10-21 13:15:06.000000000 +0800
> @@ -911,15 +911,6 @@
>  
>  	show_info();
>  
> -	if(daemon_mode) {
> -		ret = daemon(0, 0);
> -		
> -		if(ret == -1) {
> -			perror("An error occured while daemonizing.");
> -			exit(-1);
> -		}
> -	}
> -
>  	/* Connect the signal handlers */
>  	act.sa_handler = handler;
>  	act.sa_flags = 0;
> @@ -934,6 +925,15 @@
>  	if(ret = channels_init())
>  		return ret;
>  
> +	if(daemon_mode) {
> +		ret = daemon(0, 0);
> +
> +		if(ret == -1) {
> +			perror("An error occured while daemonizing.");
> +			exit(-1);
> +		}
> +	}
> +
>  	tids = malloc(sizeof(pthread_t) * num_threads);
>  	for(i=0; i<num_threads; i++) {
>  
> 
> 
> 
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-- 
Mathieu Desnoyers
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