[ltt-dev] [PATCH] LTTng: Make mark-control work in debugfs
Gui Jianfeng
guijianfeng at cn.fujitsu.com
Wed Feb 4 20:20:52 EST 2009
Mathieu Desnoyers wrote:
>
> Hrm, I'm playing a bit with the interface, and I think I should wait
> before I merge it. There are a few things to fix.
>
> First, when enabling a marker with the old ltt-marker-control.ko, if we
> rmmod the module containing this marker and after modprobe the module
> again, the marker stays enabled. With this debugfs interface, it seems
> to become disabled.
Hi Mathieu,
When enabling a marker with either way(old proc or debugfs), if this marker
belongs a module, I'm afraid this module can't be unloaded any more.
For example:
#modprobe fs_trace
#echo "connect fs close default" > /proc/ltt
#rmmod fs_trace
We'll get:
ERROR: Module fs_trace is in use
I tested under lttng-0.91, do i miss something?
>
> Also, when I connect to a marker, there is some module refcounting
> involved to make sure the marked modules stays loaded. For some reason
> I've been able to unload a module with armed markers.. this should
> probably be looked at.
Do you mean even if the marker is enabled(by using debugfs or proc interface),
the module which includes this marker are still able to be unloaded?
>
> Thirdly, when I do
>
> cd /mnt/debugfs/ltt/markers
> for a in */*/enable; do echo $a; echo 1 > $a; done
>
> I get :
> metadata/core_marker_format
> -su: echo: write error: File exists
> metadata/core_marker_id
> -su: echo: write error: File exists
>
> Which is expected, because those marker are activated within the kernel
> and should not have their state modified by the user-visible API.
>
> Then I do :
> for a in */*/enable; do echo $a; echo 0 > $a; done
>
> And do the first command again :
> for a in */*/enable; do echo $a; echo 1 > $a; done
>
> This shows that userspace is able to alter the state of builtin "core"
> markers, which I disallow in ltt-marker-control.ko. The same would be
> good in the debugfs interface.
I tried on lttng-0.91
#echo "disconnect metadata core_marker_format" > /proc/ltt
#cat /proc/ltt | grep core_marker_format
i got the following:
channel: metadata marker: core_marker_format format: "channel %s name %s format %s" state: 0 event_id: 1 call: 0xc0460b7c probe single : 0xc045f904
It seems core_marker_format has been disabled by old interface. Do i miss something again?
ltt-armall do the restriction, consider the follwing piece of code
MARKERS=`cat /proc/ltt|grep -v %k|awk '{print $2 " " $4}'|sort -u|grep -v ^metadata
| grep -v ^locking|grep -v ^lockdep`
Actually, this block of code do the restriction from userspace.
>
> 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
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