[ltt-dev] [PATCH] LTTng: Make mark-control work in debugfs

Gui Jianfeng guijianfeng at cn.fujitsu.com
Wed Feb 11 04:27:27 EST 2009


Mathieu Desnoyers wrote:
> I think I have an idea we could implement to support arming markers
> which are not loaded in the kernel yet. The use-case is :
> 
> We have a marker in a given module, which is not loaded. We are
> interested in tracing events in this module happening soon after module
> load. Therefore, we cannot use the /mnt/debugfs/ltt/markers/**/* files,
> because the marker is not present yet.
> 
> We could implement mkdir operations to support this. This is out of
> ltt-armall scope, and people would have to use it manually and *know*
> what channel and marker names they want to enable, but I think it's ok.
> 
> So basically, we would have :
> 
> cd /mnt/debugfs/ltt
> mkdir channel_name
> cd channel_name
> mkdir marker_name
> 
> The marker_name subdirectory would be populated with standard
> information and enable files.

  Do you mean if we do "mkdir channel_name" and "mkdir marker_name"
  kernel will automatically insert the probe module, but in debugfs, 
  it doesn't show all of the markers this module have, but just the 
  requested one?

> 
> Do you think it could be added easily to ltt-trace-control ?
> 
> Mathieu
> 
> 
>> Thanks,
>>
>> Mathieu
>>
>>>> I'm providing the patch modified to fit with checkpatch below.
>>>>
>>>> Thanks,
>>>>
>>>> Mathieu
>>>>
>>>>
>>>> lttng-make-mark-control-work-in-debugfs
>>>>
>>>> This patch makes mark-control work in debugfs
>>>> Control files are organized as following.
>>>> ltt/
>>>> |-- markers
>>>> |   |-- fs
>>>> |   |   |-- buffer_wait_end
>>>> |   |   |   |-- enable
>>>> |   |   |   `-- info
>>>> |   |   |-- buffer_wait_start
>>>> |   |   |   |-- enable
>>>> |   |   |   `-- info
>>>> |   |   |-- close
>>>> |   |   |   |-- enable
>>>> |   |   |   `-- info
>>>> |   |   |-- exec
>>>> |   |   |   |-- enable
>>>> |   |   |   `-- info
>>>> ...
>>>>
>>>> One can enable or disable a marker by using the following command
>>>> # echo 1 > ltt/markers/fs/close/enable
>>>> # echo 0 > ltt/markers/fs/close/enable
>>>>
>>>> Show the marker information as following 
>>>> # cat ltt/markers/fs/close/info
>>>> format: "fd %u"
>>>> state: 1
>>>> event_id: 2
>>>> call: 0xc0459118
>>>> probe single : 0xc04f7b08
>>>>
>>>> Mathieu :
>>>>
>>>> enabled -> enable to follow the semantic of the rest of the debugfs API.
>>>> checkpatch.pl cleanup.
>>>>
>>>> Signed-off-by: Gui Jianfeng <guijianfeng at cn.fujitsu.com>
>>>> Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers at polymtl.ca>
>>>> ---
>>>>  ltt/ltt-trace-control.c |  298 +++++++++++++++++++++++++++++++++++++++++++++++-
>>>>  1 file changed, 294 insertions(+), 4 deletions(-)
>>>>
>>>> Index: linux-2.6-lttng/ltt/ltt-trace-control.c
>>>> ===================================================================
>>>> --- linux-2.6-lttng.orig/ltt/ltt-trace-control.c	2009-02-04 00:56:05.000000000 -0500
>>>> +++ linux-2.6-lttng/ltt/ltt-trace-control.c	2009-02-04 01:01:46.000000000 -0500
>>>> @@ -1,8 +1,10 @@
>>>>  /*
>>>>   * LTT trace control module over debugfs.
>>>>   *
>>>> - * Copyright 2008 -
>>>> - *	Zhaolei <zhaolei at cn.fujitsu.com>
>>>> + * Copyright 2008 - Zhaolei <zhaolei at cn.fujitsu.com>
>>>> + *
>>>> + * Copyright 2009 - Gui Jianfeng <guijianfeng at cn.fujitsu.com>
>>>> + *                  Make mark-control work in debugfs
>>>>   */
>>>>  
>>>>  /*
>>>> @@ -16,14 +18,17 @@
>>>>  #include <linux/uaccess.h>
>>>>  #include <linux/debugfs.h>
>>>>  #include <linux/ltt-tracer.h>
>>>> +#include <linux/notifier.h>
>>>>  
>>>>  #define LTT_CONTROL_DIR "control"
>>>> +#define MARKERS_CONTROL_DIR "markers"
>>>>  #define LTT_SETUP_TRACE_FILE "setup_trace"
>>>>  #define LTT_DESTROY_TRACE_FILE "destroy_trace"
>>>>  
>>>>  #define LTT_WRITE_MAXLEN	(128)
>>>>  
>>>> -struct dentry *ltt_control_dir, *ltt_setup_trace_file, *ltt_destroy_trace_file;
>>>> +struct dentry *ltt_control_dir, *ltt_setup_trace_file, *ltt_destroy_trace_file,
>>>> +	*markers_control_dir;
>>>>  
>>>>  /*
>>>>   * the traces_lock nests inside control_lock.
>>>> @@ -692,6 +697,270 @@ static struct file_operations ltt_destro
>>>>  	.write = destroy_trace_write,
>>>>  };
>>>>  
>>>> +static int marker_enable_open(struct inode *inode, struct file *filp)
>>>> +{
>>>> +	filp->private_data = inode->i_private;
>>>> +	return 0;
>>>> +}
>>>> +
>>>> +static ssize_t marker_enable_read(struct file *filp, char __user *ubuf,
>>>> +			    size_t cnt, loff_t *ppos)
>>>> +{
>>>> +	struct marker *marker;
>>>> +	char *buf;
>>>> +	int len;
>>>> +
>>>> +	marker = (struct marker *)filp->private_data;
>>>> +	buf = kmalloc(1024, GFP_KERNEL);
>>>> +
>>>> +	len = sprintf(buf, "%d\n", _imv_read(marker->state));
>>>> +
>>>> +	len = simple_read_from_buffer(ubuf, cnt, ppos, buf, len);
>>>> +	kfree(buf);
>>>> +
>>>> +	return len;
>>>> +}
>>>> +
>>>> +static ssize_t marker_enable_write(struct file *filp, const char __user *ubuf,
>>>> +				size_t cnt, loff_t *ppos)
>>>> +{
>>>> +	char buf[NAME_MAX];
>>>> +	int buf_size;
>>>> +	int err = 0;
>>>> +	struct marker *marker;
>>>> +
>>>> +	marker = (struct marker *)filp->private_data;
>>>> +	buf_size = min(cnt, sizeof(buf) - 1);
>>>> +	err = copy_from_user(buf, ubuf, buf_size);
>>>> +	if (err)
>>>> +		return err;
>>>> +
>>>> +	buf[buf_size] = 0;
>>>> +
>>>> +	switch (buf[0]) {
>>>> +	case 'Y':
>>>> +	case 'y':
>>>> +	case '1':
>>>> +		err = ltt_marker_connect(marker->channel, marker->name,
>>>> +					 "default");
>>>> +		if (err)
>>>> +			return err;
>>>> +		break;
>>>> +	case 'N':
>>>> +	case 'n':
>>>> +	case '0':
>>>> +		err = ltt_marker_disconnect(marker->channel, marker->name,
>>>> +					    "default");
>>>> +		if (err)
>>>> +			return err;
>>>> +		break;
>>>> +	default:
>>>> +		return -EPERM;
>>>> +	}
>>>> +
>>>> +	return cnt;
>>>> +}
>>>> +
>>>> +static const struct file_operations enable_fops = {
>>>> +	.open = marker_enable_open,
>>>> +	.read = marker_enable_read,
>>>> +	.write = marker_enable_write,
>>>> +};
>>>> +
>>>> +static int marker_info_open(struct inode *inode, struct file *filp)
>>>> +{
>>>> +	filp->private_data = inode->i_private;
>>>> +	return 0;
>>>> +}
>>>> +
>>>> +static ssize_t marker_info_read(struct file *filp, char __user *ubuf,
>>>> +			    size_t cnt, loff_t *ppos)
>>>> +{
>>>> +	struct marker *marker;
>>>> +	char *buf;
>>>> +	int len;
>>>> +
>>>> +	marker = (struct marker *)filp->private_data;
>>>> +	buf = kmalloc(1024, GFP_KERNEL);
>>>> +
>>>> +	len = sprintf(buf, "format: \"%s\"\nstate: %d\n"
>>>> +		      "event_id: %hu\n"
>>>> +		      "call: 0x%p\n"
>>>> +		      "probe %s : 0x%p\n",
>>>> +		      marker->format, _imv_read(marker->state),
>>>> +		      marker->event_id, marker->call, marker->ptype ?
>>>> +		      "multi" : "single", marker->ptype ?
>>>> +		      (void *)marker->multi : (void *)marker->single.func);
>>>> +
>>>> +	len = simple_read_from_buffer(ubuf, cnt, ppos, buf, len);
>>>> +	kfree(buf);
>>>> +
>>>> +	return len;
>>>> +}
>>>> +
>>>> +static const struct file_operations info_fops = {
>>>> +	.open = marker_info_open,
>>>> +	.read = marker_info_read,
>>>> +};
>>>> +
>>>> +static int build_marker_file(struct marker *marker)
>>>> +{
>>>> +	struct dentry *channel_d, *marker_d, *enable_d, *info_d;
>>>> +	int err;
>>>> +
>>>> +	channel_d = dir_lookup(markers_control_dir, marker->channel);
>>>> +	if (!channel_d) {
>>>> +		channel_d = debugfs_create_dir(marker->channel,
>>>> +					       markers_control_dir);
>>>> +		if (IS_ERR(channel_d) || !channel_d) {
>>>> +			printk(KERN_ERR
>>>> +			       "%s: build channel dir of %s failed\n",
>>>> +			       __func__, marker->channel);
>>>> +			err = -ENOMEM;
>>>> +			goto err_build_fail;
>>>> +		}
>>>> +	}
>>>> +
>>>> +	marker_d  = dir_lookup(channel_d, marker->name);
>>>> +	if (!marker_d) {
>>>> +		marker_d = debugfs_create_dir(marker->name, channel_d);
>>>> +		if (IS_ERR(marker_d) || !marker_d) {
>>>> +			printk(KERN_ERR
>>>> +			       "%s: marker dir of %s failed\n",
>>>> +			       __func__, marker->name);
>>>> +			err = -ENOMEM;
>>>> +			goto err_build_fail;
>>>> +		}
>>>> +	}
>>>> +
>>>> +	enable_d = dir_lookup(marker_d, "enable");
>>>> +	if (!enable_d) {
>>>> +		enable_d = debugfs_create_file("enable", 0644, marker_d,
>>>> +						marker, &enable_fops);
>>>> +		if (IS_ERR(enable_d) || !enable_d) {
>>>> +			printk(KERN_ERR
>>>> +			       "%s: create file of %s failed\n",
>>>> +			       __func__, "enable");
>>>> +			err = -ENOMEM;
>>>> +			goto err_build_fail;
>>>> +		}
>>>> +	}
>>>> +
>>>> +	info_d = dir_lookup(marker_d, "info");
>>>> +	if (!info_d) {
>>>> +		info_d = debugfs_create_file("info", 0444, marker_d,
>>>> +						marker, &info_fops);
>>>> +		if (IS_ERR(info_d) || !info_d) {
>>>> +			printk(KERN_ERR
>>>> +			       "%s: create file of %s failed\n",
>>>> +			       __func__, "enable");
>>>> +			err = -ENOMEM;
>>>> +			goto err_build_fail;
>>>> +		}
>>>> +	}
>>>> +
>>>> +	return 0;
>>>> +
>>>> +err_build_fail:
>>>> +	return err;
>>>> +}
>>>> +
>>>> +static int build_marker_control_files(void)
>>>> +{
>>>> +	struct marker_iter iter;
>>>> +	int err;
>>>> +
>>>> +	err = 0;
>>>> +	if (!markers_control_dir)
>>>> +		return -EEXIST;
>>>> +
>>>> +	marker_iter_reset(&iter);
>>>> +	marker_iter_start(&iter);
>>>> +	for (; iter.marker != NULL; marker_iter_next(&iter)) {
>>>> +		err = build_marker_file(iter.marker);
>>>> +		if (err)
>>>> +			goto err_build_fail;
>>>> +	}
>>>> +	marker_iter_stop(&iter);
>>>> +	return 0;
>>>> +
>>>> +err_build_fail:
>>>> +	return err;
>>>> +}
>>>> +
>>>> +static int remove_marker_control_dir(struct marker *marker)
>>>> +{
>>>> +	struct dentry *channel_d, *marker_d;
>>>> +
>>>> +	channel_d = dir_lookup(markers_control_dir, marker->channel);
>>>> +	if (!channel_d)
>>>> +		return -ENOENT;
>>>> +
>>>> +	marker_d = dir_lookup(channel_d, marker->name);
>>>> +	if (!marker_d)
>>>> +		return -ENOENT;
>>>> +
>>>> +	debugfs_remove_recursive(marker_d);
>>>> +	if (list_empty(&channel_d->d_subdirs))
>>>> +		debugfs_remove(channel_d);
>>>> +
>>>> +	return 0;
>>>> +}
>>>> +
>>>> +static void cleanup_control_dir(struct marker *begin, struct marker *end)
>>>> +{
>>>> +	struct marker *iter;
>>>> +
>>>> +	if (!markers_control_dir)
>>>> +		return;
>>>> +
>>>> +	for (iter = begin; iter < end; iter++)
>>>> +		remove_marker_control_dir(iter);
>>>> +
>>>> +	return;
>>>> +}
>>>> +
>>>> +static void build_control_dir(struct marker *begin, struct marker *end)
>>>> +{
>>>> +	struct marker *iter;
>>>> +	int err;
>>>> +
>>>> +	err = 0;
>>>> +	if (!markers_control_dir)
>>>> +		return;
>>>> +
>>>> +	for (iter = begin; iter < end; iter++) {
>>>> +		err = build_marker_file(iter);
>>>> +		if (err)
>>>> +			goto err_build_fail;
>>>> +	}
>>>> +
>>>> +	return;
>>>> +err_build_fail:
>>>> +	cleanup_control_dir(begin, end);
>>>> +}
>>>> +
>>>> +static int module_notify(struct notifier_block *self,
>>>> +		  unsigned long val, void *data)
>>>> +{
>>>> +	struct module *mod = data;
>>>> +
>>>> +	switch (val) {
>>>> +	case MODULE_STATE_COMING:
>>>> +		build_control_dir(mod->markers,
>>>> +				  mod->markers + mod->num_markers);
>>>> +		break;
>>>> +	case MODULE_STATE_GOING:
>>>> +		cleanup_control_dir(mod->markers,
>>>> +				    mod->markers + mod->num_markers);
>>>> +		break;
>>>> +	}
>>>> +	return NOTIFY_DONE;
>>>> +}
>>>> +
>>>> +static struct notifier_block module_nb = {
>>>> +	.notifier_call = module_notify,
>>>> +};
>>>>  
>>>>  static int __init ltt_trace_control_init(void)
>>>>  {
>>>> @@ -733,8 +1002,27 @@ static int __init ltt_trace_control_init
>>>>  		goto err_create_destroy_trace_file;
>>>>  	}
>>>>  
>>>> -	return 0;
>>>> +	markers_control_dir = debugfs_create_dir(MARKERS_CONTROL_DIR,
>>>> +						 ltt_root_dentry);
>>>> +	if (IS_ERR(markers_control_dir) || !markers_control_dir) {
>>>> +		printk(KERN_ERR
>>>> +			"ltt_channel_control_init: create dir of %s failed\n",
>>>> +			MARKERS_CONTROL_DIR);
>>>> +		err = -ENOMEM;
>>>> +		goto err_create_marker_control_dir;
>>>> +	}
>>>>  
>>>> +	if (build_marker_control_files())
>>>> +		goto err_build_fail;
>>>> +
>>>> +	if (!register_module_notifier(&module_nb))
>>>> +		return 0;
>>>> +
>>>> +err_build_fail:
>>>> +	debugfs_remove_recursive(markers_control_dir);
>>>> +	markers_control_dir = NULL;
>>>> +err_create_marker_control_dir:
>>>> +	debugfs_remove(ltt_destroy_trace_file);
>>>>  err_create_destroy_trace_file:
>>>>  	debugfs_remove(ltt_setup_trace_file);
>>>>  err_create_setup_trace_file:
>>>> @@ -759,6 +1047,8 @@ static void __exit ltt_trace_control_exi
>>>>  	debugfs_remove(ltt_setup_trace_file);
>>>>  	debugfs_remove(ltt_destroy_trace_file);
>>>>  	debugfs_remove_recursive(ltt_control_dir);
>>>> +	debugfs_remove_recursive(markers_control_dir);
>>>> +	unregister_module_notifier(&module_nb);
>>>>  }
>>>>  
>>>>  module_init(ltt_trace_control_init);
>>>>
>>>>
>>> -- 
>>> Regards
>>> Gui Jianfeng
>>>
>>>
>>>
>>> _______________________________________________
>>> ltt-dev mailing list
>>> ltt-dev at lists.casi.polymtl.ca
>>> http://lists.casi.polymtl.ca/cgi-bin/mailman/listinfo/ltt-dev
>>>
>> -- 
>> Mathieu Desnoyers
>> OpenPGP key fingerprint: 8CD5 52C3 8E3C 4140 715F  BA06 3F25 A8FE 3BAE 9A68
> 

-- 
Regards
Gui Jianfeng




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