Commit 28879787 authored by Divya Indi's avatar Divya Indi Committed by Steven Rostedt (VMware)

tracing: Adding new functions for kernel access to Ftrace instances

Adding 2 new functions -
1) struct trace_array *trace_array_get_by_name(const char *name);

Return pointer to a trace array with given name. If it does not exist,
create and return pointer to the new trace array.

2) int trace_array_set_clr_event(struct trace_array *tr,
const char *system ,const char *event, bool enable);

Enable/Disable events to this trace array.

Additionally,
- To handle reference counters, export trace_array_put()
- Due to introduction of the above 2 new functions, we no longer need to
  export - ftrace_set_clr_event & trace_array_create APIs.

Link: http://lkml.kernel.org/r/1574276919-11119-2-git-send-email-divya.indi@oracle.comSigned-off-by: default avatarDivya Indi <divya.indi@oracle.com>
Reviewed-by: default avatarAruna Ramakrishna <aruna.ramakrishna@oracle.com>
Signed-off-by: default avatarSteven Rostedt (VMware) <rostedt@goodmis.org>
parent fc809bc5
......@@ -29,7 +29,8 @@ struct trace_array;
void trace_printk_init_buffers(void);
int trace_array_printk(struct trace_array *tr, unsigned long ip,
const char *fmt, ...);
struct trace_array *trace_array_create(const char *name);
void trace_array_put(struct trace_array *tr);
struct trace_array *trace_array_get_by_name(const char *name);
int trace_array_destroy(struct trace_array *tr);
#endif /* CONFIG_TRACING */
......
......@@ -555,7 +555,8 @@ extern int trace_event_get_offsets(struct trace_event_call *call);
int ftrace_set_clr_event(struct trace_array *tr, char *buf, int set);
int trace_set_clr_event(const char *system, const char *event, int set);
int trace_array_set_clr_event(struct trace_array *tr, const char *system,
const char *event, bool enable);
/*
* The double __builtin_constant_p is because gcc will give us an error
* if we try to allocate the static variable to fmt if it is not a
......
......@@ -301,12 +301,24 @@ static void __trace_array_put(struct trace_array *this_tr)
this_tr->ref--;
}
/**
* trace_array_put - Decrement the reference counter for this trace array.
*
* NOTE: Use this when we no longer need the trace array returned by
* trace_array_get_by_name(). This ensures the trace array can be later
* destroyed.
*
*/
void trace_array_put(struct trace_array *this_tr)
{
if (!this_tr)
return;
mutex_lock(&trace_types_lock);
__trace_array_put(this_tr);
mutex_unlock(&trace_types_lock);
}
EXPORT_SYMBOL_GPL(trace_array_put);
int tracing_check_open_get_tr(struct trace_array *tr)
{
......@@ -8437,24 +8449,15 @@ static void update_tracer_options(struct trace_array *tr)
mutex_unlock(&trace_types_lock);
}
struct trace_array *trace_array_create(const char *name)
static struct trace_array *trace_array_create(const char *name)
{
struct trace_array *tr;
int ret;
mutex_lock(&event_mutex);
mutex_lock(&trace_types_lock);
ret = -EEXIST;
list_for_each_entry(tr, &ftrace_trace_arrays, list) {
if (tr->name && strcmp(tr->name, name) == 0)
goto out_unlock;
}
ret = -ENOMEM;
tr = kzalloc(sizeof(*tr), GFP_KERNEL);
if (!tr)
goto out_unlock;
return ERR_PTR(ret);
tr->name = kstrdup(name, GFP_KERNEL);
if (!tr->name)
......@@ -8499,8 +8502,8 @@ struct trace_array *trace_array_create(const char *name)
list_add(&tr->list, &ftrace_trace_arrays);
mutex_unlock(&trace_types_lock);
mutex_unlock(&event_mutex);
tr->ref++;
return tr;
......@@ -8510,24 +8513,77 @@ struct trace_array *trace_array_create(const char *name)
kfree(tr->name);
kfree(tr);
out_unlock:
mutex_unlock(&trace_types_lock);
mutex_unlock(&event_mutex);
return ERR_PTR(ret);
}
EXPORT_SYMBOL_GPL(trace_array_create);
static int instance_mkdir(const char *name)
{
return PTR_ERR_OR_ZERO(trace_array_create(name));
struct trace_array *tr;
int ret;
mutex_lock(&event_mutex);
mutex_lock(&trace_types_lock);
ret = -EEXIST;
list_for_each_entry(tr, &ftrace_trace_arrays, list) {
if (tr->name && strcmp(tr->name, name) == 0)
goto out_unlock;
}
tr = trace_array_create(name);
ret = PTR_ERR_OR_ZERO(tr);
out_unlock:
mutex_unlock(&trace_types_lock);
mutex_unlock(&event_mutex);
return ret;
}
/**
* trace_array_get_by_name - Create/Lookup a trace array, given its name.
* @name: The name of the trace array to be looked up/created.
*
* Returns pointer to trace array with given name.
* NULL, if it cannot be created.
*
* NOTE: This function increments the reference counter associated with the
* trace array returned. This makes sure it cannot be freed while in use.
* Use trace_array_put() once the trace array is no longer needed.
*
*/
struct trace_array *trace_array_get_by_name(const char *name)
{
struct trace_array *tr;
mutex_lock(&event_mutex);
mutex_lock(&trace_types_lock);
list_for_each_entry(tr, &ftrace_trace_arrays, list) {
if (tr->name && strcmp(tr->name, name) == 0)
goto out_unlock;
}
tr = trace_array_create(name);
if (IS_ERR(tr))
tr = NULL;
out_unlock:
if (tr)
tr->ref++;
mutex_unlock(&trace_types_lock);
mutex_unlock(&event_mutex);
return tr;
}
EXPORT_SYMBOL_GPL(trace_array_get_by_name);
static int __remove_instance(struct trace_array *tr)
{
int i;
if (tr->ref || (tr->current_trace && tr->current_trace->ref))
/* Reference counter for a newly created trace array = 1. */
if (tr->ref > 1 || (tr->current_trace && tr->current_trace->ref))
return -EBUSY;
list_del(&tr->list);
......
......@@ -345,7 +345,6 @@ extern struct list_head ftrace_trace_arrays;
extern struct mutex trace_types_lock;
extern int trace_array_get(struct trace_array *tr);
extern void trace_array_put(struct trace_array *tr);
extern int tracing_check_open_get_tr(struct trace_array *tr);
extern int tracing_set_time_stamp_abs(struct trace_array *tr, bool abs);
......
......@@ -827,7 +827,6 @@ int ftrace_set_clr_event(struct trace_array *tr, char *buf, int set)
return ret;
}
EXPORT_SYMBOL_GPL(ftrace_set_clr_event);
/**
* trace_set_clr_event - enable or disable an event
......@@ -852,6 +851,32 @@ int trace_set_clr_event(const char *system, const char *event, int set)
}
EXPORT_SYMBOL_GPL(trace_set_clr_event);
/**
* trace_array_set_clr_event - enable or disable an event for a trace array.
* @tr: concerned trace array.
* @system: system name to match (NULL for any system)
* @event: event name to match (NULL for all events, within system)
* @enable: true to enable, false to disable
*
* This is a way for other parts of the kernel to enable or disable
* event recording.
*
* Returns 0 on success, -EINVAL if the parameters do not match any
* registered events.
*/
int trace_array_set_clr_event(struct trace_array *tr, const char *system,
const char *event, bool enable)
{
int set;
if (!tr)
return -ENOENT;
set = (enable == true) ? 1 : 0;
return __ftrace_set_clr_event(tr, NULL, system, event, set);
}
EXPORT_SYMBOL_GPL(trace_array_set_clr_event);
/* 128 should be much more than enough */
#define EVENT_BUF_SIZE 127
......
Markdown is supported
0%
or
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment