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-rw-r--r--kernel/trace/trace.h1
-rw-r--r--kernel/trace/trace_events.c86
-rw-r--r--kernel/trace/trace_events_filter.c6
3 files changed, 82 insertions, 11 deletions
diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index 229f859..f807407 100644
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -677,6 +677,7 @@ struct event_subsystem {
struct dentry *entry;
struct event_filter *filter;
int nr_events;
+ int ref_count;
};
#define FILTER_PRED_INVALID ((unsigned short)-1)
diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c
index 686ec39..ffc5b28 100644
--- a/kernel/trace/trace_events.c
+++ b/kernel/trace/trace_events.c
@@ -244,6 +244,35 @@ static void ftrace_clear_events(void)
mutex_unlock(&event_mutex);
}
+static void __put_system(struct event_subsystem *system)
+{
+ struct event_filter *filter = system->filter;
+
+ WARN_ON_ONCE(system->ref_count == 0);
+ if (--system->ref_count)
+ return;
+
+ if (filter) {
+ kfree(filter->filter_string);
+ kfree(filter);
+ }
+ kfree(system->name);
+ kfree(system);
+}
+
+static void __get_system(struct event_subsystem *system)
+{
+ WARN_ON_ONCE(system->ref_count == 0);
+ system->ref_count++;
+}
+
+static void put_system(struct event_subsystem *system)
+{
+ mutex_lock(&event_mutex);
+ __put_system(system);
+ mutex_unlock(&event_mutex);
+}
+
/*
* __ftrace_set_clr_event(NULL, NULL, NULL, set) will set/unset all events.
*/
@@ -826,6 +855,47 @@ event_filter_write(struct file *filp, const char __user *ubuf, size_t cnt,
return cnt;
}
+static LIST_HEAD(event_subsystems);
+
+static int subsystem_open(struct inode *inode, struct file *filp)
+{
+ struct event_subsystem *system = NULL;
+ int ret;
+
+ /* Make sure the system still exists */
+ mutex_lock(&event_mutex);
+ list_for_each_entry(system, &event_subsystems, list) {
+ if (system == inode->i_private) {
+ /* Don't open systems with no events */
+ if (!system->nr_events) {
+ system = NULL;
+ break;
+ }
+ __get_system(system);
+ break;
+ }
+ }
+ mutex_unlock(&event_mutex);
+
+ if (system != inode->i_private)
+ return -ENODEV;
+
+ ret = tracing_open_generic(inode, filp);
+ if (ret < 0)
+ put_system(system);
+
+ return ret;
+}
+
+static int subsystem_release(struct inode *inode, struct file *file)
+{
+ struct event_subsystem *system = inode->i_private;
+
+ put_system(system);
+
+ return 0;
+}
+
static ssize_t
subsystem_filter_read(struct file *filp, char __user *ubuf, size_t cnt,
loff_t *ppos)
@@ -963,10 +1033,11 @@ static const struct file_operations ftrace_event_filter_fops = {
};
static const struct file_operations ftrace_subsystem_filter_fops = {
- .open = tracing_open_generic,
+ .open = subsystem_open,
.read = subsystem_filter_read,
.write = subsystem_filter_write,
.llseek = default_llseek,
+ .release = subsystem_release,
};
static const struct file_operations ftrace_system_enable_fops = {
@@ -1002,8 +1073,6 @@ static struct dentry *event_trace_events_dir(void)
return d_events;
}
-static LIST_HEAD(event_subsystems);
-
static struct dentry *
event_subsystem_dir(const char *name, struct dentry *d_events)
{
@@ -1013,6 +1082,7 @@ event_subsystem_dir(const char *name, struct dentry *d_events)
/* First see if we did not already create this dir */
list_for_each_entry(system, &event_subsystems, list) {
if (strcmp(system->name, name) == 0) {
+ __get_system(system);
system->nr_events++;
return system->entry;
}
@@ -1035,6 +1105,7 @@ event_subsystem_dir(const char *name, struct dentry *d_events)
}
system->nr_events = 1;
+ system->ref_count = 1;
system->name = kstrdup(name, GFP_KERNEL);
if (!system->name) {
debugfs_remove(system->entry);
@@ -1184,16 +1255,9 @@ static void remove_subsystem_dir(const char *name)
list_for_each_entry(system, &event_subsystems, list) {
if (strcmp(system->name, name) == 0) {
if (!--system->nr_events) {
- struct event_filter *filter = system->filter;
-
debugfs_remove_recursive(system->entry);
list_del(&system->list);
- if (filter) {
- kfree(filter->filter_string);
- kfree(filter);
- }
- kfree(system->name);
- kfree(system);
+ __put_system(system);
}
break;
}
diff --git a/kernel/trace/trace_events_filter.c b/kernel/trace/trace_events_filter.c
index 8008ddc..256764e 100644
--- a/kernel/trace/trace_events_filter.c
+++ b/kernel/trace/trace_events_filter.c
@@ -1886,6 +1886,12 @@ int apply_subsystem_event_filter(struct event_subsystem *system,
mutex_lock(&event_mutex);
+ /* Make sure the system still has events */
+ if (!system->nr_events) {
+ err = -ENODEV;
+ goto out_unlock;
+ }
+
if (!strcmp(strstrip(filter_string), "0")) {
filter_free_subsystem_preds(system);
remove_filter_string(system->filter);