Adding 2 new functions -
1) trace_array_lookup : Look up and return a trace array, given its
name.
2) trace_array_set_clr_event : Enable/disable event recording to the
given trace array.
NOTE: trace_array_lookup returns a trace array and also increments the
reference counter associated with the returned trace array. Make sure to
call trace_array_put() once the use is done so that the instance can be
removed at a later time.
Example use:
tr = trace_array_lookup("foo-bar");
if (!tr)
tr = trace_array_create("foo-bar");
// Log to tr
// Enable/disable events to tr
trace_array_set_clr_event(tr, _THIS_IP,"system","event",1);
// Done using tr
trace_array_put(tr);
..
Also, use trace_array_set_clr_event to enable/disable events to a trace array.
So now we no longer need to have ftrace_set_clr_event as an exported
API.
Signed-off-by: Divya Indi <[email protected]>
---
include/linux/trace.h | 2 ++
include/linux/trace_events.h | 3 ++-
kernel/trace/trace.c | 28 ++++++++++++++++++++++++++++
kernel/trace/trace_events.c | 23 ++++++++++++++++++++++-
4 files changed, 54 insertions(+), 2 deletions(-)
diff --git a/include/linux/trace.h b/include/linux/trace.h
index 2c782d5..05164bb 100644
--- a/include/linux/trace.h
+++ b/include/linux/trace.h
@@ -32,6 +32,8 @@ int trace_array_printk(struct trace_array *tr, unsigned long ip,
struct trace_array *trace_array_create(const char *name);
int trace_array_destroy(struct trace_array *tr);
void trace_array_put(struct trace_array *tr);
+struct trace_array *trace_array_lookup(const char *name);
+
#endif /* CONFIG_TRACING */
#endif /* _LINUX_TRACE_H */
diff --git a/include/linux/trace_events.h b/include/linux/trace_events.h
index 8a62731..05a7514 100644
--- a/include/linux/trace_events.h
+++ b/include/linux/trace_events.h
@@ -540,7 +540,8 @@ extern int trace_define_field(struct trace_event_call *call, const char *type,
#define is_signed_type(type) (((type)(-1)) < (type)1)
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, int set);
/*
* 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
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 7b6a37a..e394d55 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -8514,6 +8514,34 @@ static int instance_rmdir(const char *name)
return ret;
}
+/**
+ * trace_array_lookup - Lookup the trace array, given its name.
+ * @name: The name of the trace array to be looked up.
+ *
+ * Lookup and return the trace array associated with @name.
+ *
+ * NOTE: The reference counter associated with the returned trace array is
+ * incremented to ensure it is not freed when in use. Make sure to call
+ * "trace_array_put" for this trace array when its use is done.
+ */
+struct trace_array *trace_array_lookup(const char *name)
+{
+ struct trace_array *tr;
+
+ mutex_lock(&trace_types_lock);
+
+ list_for_each_entry(tr, &ftrace_trace_arrays, list) {
+ if (tr->name && strcmp(tr->name, name) == 0) {
+ tr->ref++;
+ mutex_unlock(&trace_types_lock);
+ return tr;
+ }
+ }
+ mutex_unlock(&trace_types_lock);
+ return NULL;
+}
+EXPORT_SYMBOL_GPL(trace_array_lookup);
+
static __init void create_trace_instances(struct dentry *d_tracer)
{
trace_instance_dir = tracefs_create_instance_dir("instances", d_tracer,
diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c
index 2621995..96dd997 100644
--- a/kernel/trace/trace_events.c
+++ b/kernel/trace/trace_events.c
@@ -834,7 +834,6 @@ static 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
@@ -859,6 +858,28 @@ 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
+ * @system: system name to match (NULL for any system)
+ * @event: event name to match (NULL for all events, within system)
+ * @set: 1 to enable, 0 to disable
+ *
+ * This is a way for other parts of the kernel to enable or disable
+ * event recording to instances.
+ *
+ * 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, int set)
+{
+ if (!tr)
+ return -ENOENT;
+
+ 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
--
1.8.3.1
On Wed, 14 Aug 2019 10:55:27 -0700
Divya Indi <[email protected]> wrote:
> Adding 2 new functions -
> 1) trace_array_lookup : Look up and return a trace array, given its
> name.
> 2) trace_array_set_clr_event : Enable/disable event recording to the
> given trace array.
>
> NOTE: trace_array_lookup returns a trace array and also increments the
> reference counter associated with the returned trace array. Make sure to
> call trace_array_put() once the use is done so that the instance can be
> removed at a later time.
>
> Example use:
>
> tr = trace_array_lookup("foo-bar");
Should probably be renamed to: trace_array_get_by_name("foo-bar")
As the name should show that it adds a ref count.
But if we make the change I suggested before, where we do not need to
do the put before calling the destroy, we should have:
> if (!tr)
{
> tr = trace_array_create("foo-bar");
trace_array_get(tr);
}
> // Log to tr
> // Enable/disable events to tr
> trace_array_set_clr_event(tr, _THIS_IP,"system","event",1);
What's with the __THIS_IP?
>
> // Done using tr
> trace_array_put(tr);
> ..
>
> Also, use trace_array_set_clr_event to enable/disable events to a trace array.
> So now we no longer need to have ftrace_set_clr_event as an exported
> API.
>
> Signed-off-by: Divya Indi <[email protected]>
> ---
> include/linux/trace.h | 2 ++
> include/linux/trace_events.h | 3 ++-
> kernel/trace/trace.c | 28 ++++++++++++++++++++++++++++
> kernel/trace/trace_events.c | 23 ++++++++++++++++++++++-
> 4 files changed, 54 insertions(+), 2 deletions(-)
>
> diff --git a/include/linux/trace.h b/include/linux/trace.h
> index 2c782d5..05164bb 100644
> --- a/include/linux/trace.h
> +++ b/include/linux/trace.h
> @@ -32,6 +32,8 @@ int trace_array_printk(struct trace_array *tr, unsigned long ip,
> struct trace_array *trace_array_create(const char *name);
> int trace_array_destroy(struct trace_array *tr);
> void trace_array_put(struct trace_array *tr);
> +struct trace_array *trace_array_lookup(const char *name);
> +
> #endif /* CONFIG_TRACING */
>
> #endif /* _LINUX_TRACE_H */
> diff --git a/include/linux/trace_events.h b/include/linux/trace_events.h
> index 8a62731..05a7514 100644
> --- a/include/linux/trace_events.h
> +++ b/include/linux/trace_events.h
> @@ -540,7 +540,8 @@ extern int trace_define_field(struct trace_event_call *call, const char *type,
> #define is_signed_type(type) (((type)(-1)) < (type)1)
>
> 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, int set);
> /*
> * 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
> diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
> index 7b6a37a..e394d55 100644
> --- a/kernel/trace/trace.c
> +++ b/kernel/trace/trace.c
> @@ -8514,6 +8514,34 @@ static int instance_rmdir(const char *name)
> return ret;
> }
>
> +/**
> + * trace_array_lookup - Lookup the trace array, given its name.
> + * @name: The name of the trace array to be looked up.
> + *
> + * Lookup and return the trace array associated with @name.
> + *
> + * NOTE: The reference counter associated with the returned trace array is
> + * incremented to ensure it is not freed when in use. Make sure to call
> + * "trace_array_put" for this trace array when its use is done.
> + */
> +struct trace_array *trace_array_lookup(const char *name)
> +{
> + struct trace_array *tr;
> +
> + mutex_lock(&trace_types_lock);
> +
> + list_for_each_entry(tr, &ftrace_trace_arrays, list) {
> + if (tr->name && strcmp(tr->name, name) == 0) {
> + tr->ref++;
> + mutex_unlock(&trace_types_lock);
> + return tr;
> + }
> + }
> + mutex_unlock(&trace_types_lock);
> + return NULL;
> +}
> +EXPORT_SYMBOL_GPL(trace_array_lookup);
> +
> static __init void create_trace_instances(struct dentry *d_tracer)
> {
> trace_instance_dir = tracefs_create_instance_dir("instances", d_tracer,
> diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c
> index 2621995..96dd997 100644
> --- a/kernel/trace/trace_events.c
> +++ b/kernel/trace/trace_events.c
> @@ -834,7 +834,6 @@ static 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
> @@ -859,6 +858,28 @@ 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
> + * @system: system name to match (NULL for any system)
> + * @event: event name to match (NULL for all events, within system)
> + * @set: 1 to enable, 0 to disable
We probably should make this a boolean.
-- Steve
> + *
> + * This is a way for other parts of the kernel to enable or disable
> + * event recording to instances.
> + *
> + * 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, int set)
> +{
> + if (!tr)
> + return -ENOENT;
> +
> + 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
>
Hi Steven,
Please find my comments inline -
On 10/15/19 4:19 PM, Steven Rostedt wrote:
> On Wed, 14 Aug 2019 10:55:27 -0700
> Divya Indi <[email protected]> wrote:
>
>> Adding 2 new functions -
>> 1) trace_array_lookup : Look up and return a trace array, given its
>> name.
>> 2) trace_array_set_clr_event : Enable/disable event recording to the
>> given trace array.
>>
>> NOTE: trace_array_lookup returns a trace array and also increments the
>> reference counter associated with the returned trace array. Make sure to
>> call trace_array_put() once the use is done so that the instance can be
>> removed at a later time.
>>
>> Example use:
>>
>> tr = trace_array_lookup("foo-bar");
> Should probably be renamed to: trace_array_get_by_name("foo-bar")
>
> As the name should show that it adds a ref count.
Makes sense! Will make this change.
>
> But if we make the change I suggested before, where we do not need to
> do the put before calling the destroy, we should have:
>
>
>> if (!tr)
> {
>> tr = trace_array_create("foo-bar");
> trace_array_get(tr);
This would need a corresponding trace_array_put(?).
Additionally, this would again traverse the list of instances, So I
went with incrementing the ref ctr inside the function.
> }
>
>
>> // Log to tr
>> // Enable/disable events to tr
>> trace_array_set_clr_event(tr, _THIS_IP,"system","event",1);
> What's with the __THIS_IP?
My bad! Maybe remnants from a trace_array_printk copy-paste.
Will correct this.
>
>
>> // Done using tr
>> trace_array_put(tr);
>> ..
>>
>> Also, use trace_array_set_clr_event to enable/disable events to a trace array.
>> So now we no longer need to have ftrace_set_clr_event as an exported
>> API.
>>
>> Signed-off-by: Divya Indi <[email protected]>
>> ---
>> include/linux/trace.h | 2 ++
>> include/linux/trace_events.h | 3 ++-
>> kernel/trace/trace.c | 28 ++++++++++++++++++++++++++++
>> kernel/trace/trace_events.c | 23 ++++++++++++++++++++++-
>> 4 files changed, 54 insertions(+), 2 deletions(-)
>>
>> diff --git a/include/linux/trace.h b/include/linux/trace.h
>> index 2c782d5..05164bb 100644
>> --- a/include/linux/trace.h
>> +++ b/include/linux/trace.h
>> @@ -32,6 +32,8 @@ int trace_array_printk(struct trace_array *tr, unsigned long ip,
>> struct trace_array *trace_array_create(const char *name);
>> int trace_array_destroy(struct trace_array *tr);
>> void trace_array_put(struct trace_array *tr);
>> +struct trace_array *trace_array_lookup(const char *name);
>> +
>> #endif /* CONFIG_TRACING */
>>
>> #endif /* _LINUX_TRACE_H */
>> diff --git a/include/linux/trace_events.h b/include/linux/trace_events.h
>> index 8a62731..05a7514 100644
>> --- a/include/linux/trace_events.h
>> +++ b/include/linux/trace_events.h
>> @@ -540,7 +540,8 @@ extern int trace_define_field(struct trace_event_call *call, const char *type,
>> #define is_signed_type(type) (((type)(-1)) < (type)1)
>>
>> 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, int set);
>> /*
>> * 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
>> diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
>> index 7b6a37a..e394d55 100644
>> --- a/kernel/trace/trace.c
>> +++ b/kernel/trace/trace.c
>> @@ -8514,6 +8514,34 @@ static int instance_rmdir(const char *name)
>> return ret;
>> }
>>
>> +/**
>> + * trace_array_lookup - Lookup the trace array, given its name.
>> + * @name: The name of the trace array to be looked up.
>> + *
>> + * Lookup and return the trace array associated with @name.
>> + *
>> + * NOTE: The reference counter associated with the returned trace array is
>> + * incremented to ensure it is not freed when in use. Make sure to call
>> + * "trace_array_put" for this trace array when its use is done.
>> + */
>> +struct trace_array *trace_array_lookup(const char *name)
>> +{
>> + struct trace_array *tr;
>> +
>> + mutex_lock(&trace_types_lock);
>> +
>> + list_for_each_entry(tr, &ftrace_trace_arrays, list) {
>> + if (tr->name && strcmp(tr->name, name) == 0) {
>> + tr->ref++;
>> + mutex_unlock(&trace_types_lock);
>> + return tr;
>> + }
>> + }
>> + mutex_unlock(&trace_types_lock);
>> + return NULL;
>> +}
>> +EXPORT_SYMBOL_GPL(trace_array_lookup);
>> +
>> static __init void create_trace_instances(struct dentry *d_tracer)
>> {
>> trace_instance_dir = tracefs_create_instance_dir("instances", d_tracer,
>> diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c
>> index 2621995..96dd997 100644
>> --- a/kernel/trace/trace_events.c
>> +++ b/kernel/trace/trace_events.c
>> @@ -834,7 +834,6 @@ static 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
>> @@ -859,6 +858,28 @@ 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
>> + * @system: system name to match (NULL for any system)
>> + * @event: event name to match (NULL for all events, within system)
>> + * @set: 1 to enable, 0 to disable
> We probably should make this a boolean.
This would internally call ftrace_set_clr_event which would expect 0/1.
But I agree making it boolean would be more intuitive.
Thanks,
Divya
>
> -- Steve
>
>> + *
>> + * This is a way for other parts of the kernel to enable or disable
>> + * event recording to instances.
>> + *
>> + * 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, int set)
>> +{
>> + if (!tr)
>> + return -ENOENT;
>> +
>> + 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
>>