[ltt-dev] [PATCH] LTTng: Make mark-control work in debugfs
Mathieu Desnoyers
compudj at krystal.dyndns.org
Wed Feb 4 02:12:55 EST 2009
* Gui Jianfeng (guijianfeng at cn.fujitsu.com) wrote:
> Mathieu Desnoyers wrote:
> > * Gui Jianfeng (guijianfeng at cn.fujitsu.com) wrote:
> >> Hi Mathieu,
> >>
> >> This patch makes mark-control work in debugfs
> >> Control files are organized as following.
> >> ltt/
> >> |-- markers
> >> | |-- fs
> >> | | |-- buffer_wait_end
> >> | | | |-- enabled
> >> | | | `-- info
> >> | | |-- buffer_wait_start
> >> | | | |-- enabled
> >> | | | `-- info
> >> | | |-- close
> >> | | | |-- enabled
> >> | | | `-- info
> >> | | |-- exec
> >> | | | |-- enabled
> >> | | | `-- info
> >> ...
> >>
> >> One can enable or disable a marker by using the following command
> >> # echo 1 > ltt/markers/fs/close/enabled
> >> # echo 0 > ltt/markers/fs/close/enabled
> >>
> >> 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
> >>
> >
> > Thanks a lot Gui, this is a very good patch. I'll make the cosmetic
> > changes requested by scripts/checkpatch.pl myself and merge it. (please
>
> I see, thanks for pointing this out. :)
>
> BTW, I'll post a patch to modify user tools accordingly as soon as this patch
> has been merged into the new version of LTTng.
>
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.
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.
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'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);
--
Mathieu Desnoyers
OpenPGP key fingerprint: 8CD5 52C3 8E3C 4140 715F BA06 3F25 A8FE 3BAE 9A68
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