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.
Newly added functions trace_array_lookup and trace_array_create also
need to increment the reference counter associated with the trace array
they return. This is to ensure the trace array does not get freed
while in use by the newly introduced APIs.
The reference ctr is decremented in the trace_array_destroy.
Signed-off-by: Divya Indi <[email protected]>
---
include/linux/trace_events.h | 3 +++
kernel/trace/trace.c | 30 +++++++++++++++++++++++++++++-
kernel/trace/trace_events.c | 22 ++++++++++++++++++++++
3 files changed, 54 insertions(+), 1 deletion(-)
diff --git a/include/linux/trace_events.h b/include/linux/trace_events.h
index d7b7d85..0cc99a8 100644
--- a/include/linux/trace_events.h
+++ b/include/linux/trace_events.h
@@ -545,7 +545,10 @@ 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);
int ftrace_set_clr_event(struct trace_array *tr, char *buf, int set);
+struct trace_array *trace_array_lookup(const char *name);
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
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index a60dc13..fb70ccc 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -8364,6 +8364,8 @@ struct trace_array *trace_array_create(const char *name)
list_add(&tr->list, &ftrace_trace_arrays);
+ tr->ref++;
+
mutex_unlock(&trace_types_lock);
mutex_unlock(&event_mutex);
@@ -8385,7 +8387,14 @@ struct trace_array *trace_array_create(const char *name)
static int instance_mkdir(const char *name)
{
- return PTR_ERR_OR_ZERO(trace_array_create(name));
+ struct trace_array *tr;
+
+ tr = trace_array_create(name);
+ if (IS_ERR(tr))
+ return PTR_ERR(tr);
+ trace_array_put(tr);
+
+ return 0;
}
static int __remove_instance(struct trace_array *tr)
@@ -8434,6 +8443,7 @@ int trace_array_destroy(struct trace_array *tr)
mutex_lock(&event_mutex);
mutex_lock(&trace_types_lock);
+ tr->ref--;
ret = __remove_instance(tr);
mutex_unlock(&trace_types_lock);
@@ -8465,6 +8475,24 @@ static int instance_rmdir(const char *name)
return ret;
}
+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 445b059..c126d2c 100644
--- a/kernel/trace/trace_events.c
+++ b/kernel/trace/trace_events.c
@@ -859,6 +859,28 @@ 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 -ENODEV;
+
+ 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, 12 Jun 2019 09:34:19 -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.
>
> Newly added functions trace_array_lookup and trace_array_create also
> need to increment the reference counter associated with the trace array
> they return. This is to ensure the trace array does not get freed
> while in use by the newly introduced APIs.
> The reference ctr is decremented in the trace_array_destroy.
>
> Signed-off-by: Divya Indi <[email protected]>
> ---
> include/linux/trace_events.h | 3 +++
> kernel/trace/trace.c | 30 +++++++++++++++++++++++++++++-
> kernel/trace/trace_events.c | 22 ++++++++++++++++++++++
> 3 files changed, 54 insertions(+), 1 deletion(-)
>
> diff --git a/include/linux/trace_events.h b/include/linux/trace_events.h
> index d7b7d85..0cc99a8 100644
> --- a/include/linux/trace_events.h
> +++ b/include/linux/trace_events.h
> @@ -545,7 +545,10 @@ 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);
> int ftrace_set_clr_event(struct trace_array *tr, char *buf, int set);
> +struct trace_array *trace_array_lookup(const char *name);
> 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
> diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
> index a60dc13..fb70ccc 100644
> --- a/kernel/trace/trace.c
> +++ b/kernel/trace/trace.c
> @@ -8364,6 +8364,8 @@ struct trace_array *trace_array_create(const char *name)
>
> list_add(&tr->list, &ftrace_trace_arrays);
>
> + tr->ref++;
> +
Needs a comment for why the ref is incremented.
> mutex_unlock(&trace_types_lock);
> mutex_unlock(&event_mutex);
>
> @@ -8385,7 +8387,14 @@ struct trace_array *trace_array_create(const char *name)
>
> static int instance_mkdir(const char *name)
> {
> - return PTR_ERR_OR_ZERO(trace_array_create(name));
> + struct trace_array *tr;
> +
> + tr = trace_array_create(name);
> + if (IS_ERR(tr))
> + return PTR_ERR(tr);
> + trace_array_put(tr);
Need a comment to why we need to do a put here.
> +
> + return 0;
> }
>
> static int __remove_instance(struct trace_array *tr)
> @@ -8434,6 +8443,7 @@ int trace_array_destroy(struct trace_array *tr)
> mutex_lock(&event_mutex);
> mutex_lock(&trace_types_lock);
>
> + tr->ref--;
> ret = __remove_instance(tr);
>
> mutex_unlock(&trace_types_lock);
> @@ -8465,6 +8475,24 @@ static int instance_rmdir(const char *name)
> return ret;
> }
>
Need a kerneldoc heading here, that also states that if a trace_array
is returned, it requires a call to trace_array_put().
> +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 445b059..c126d2c 100644
> --- a/kernel/trace/trace_events.c
> +++ b/kernel/trace/trace_events.c
> @@ -859,6 +859,28 @@ 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 -ENODEV;
If we have this, should we get rid of the external use of
ftrace_set_clr_event()?
-- Steve
> +
> + 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,
Thanks for reviewing the patch. I have made a note of all the suggested
changes, comment requirements.
Will send them out soon as v2.
(comments inline)
On 6/17/19 4:45 PM, Steven Rostedt wrote:
> On Wed, 12 Jun 2019 09:34:19 -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.
>>
>> Newly added functions trace_array_lookup and trace_array_create also
>> need to increment the reference counter associated with the trace array
>> they return. This is to ensure the trace array does not get freed
>> while in use by the newly introduced APIs.
>> The reference ctr is decremented in the trace_array_destroy.
>>
>> Signed-off-by: Divya Indi <[email protected]>
>> ---
>> include/linux/trace_events.h | 3 +++
>> kernel/trace/trace.c | 30 +++++++++++++++++++++++++++++-
>> kernel/trace/trace_events.c | 22 ++++++++++++++++++++++
>> 3 files changed, 54 insertions(+), 1 deletion(-)
>>
>> diff --git a/include/linux/trace_events.h b/include/linux/trace_events.h
>> index d7b7d85..0cc99a8 100644
>> --- a/include/linux/trace_events.h
>> +++ b/include/linux/trace_events.h
>> @@ -545,7 +545,10 @@ 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);
>> int ftrace_set_clr_event(struct trace_array *tr, char *buf, int set);
>> +struct trace_array *trace_array_lookup(const char *name);
>> 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
>> diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
>> index a60dc13..fb70ccc 100644
>> --- a/kernel/trace/trace.c
>> +++ b/kernel/trace/trace.c
>> @@ -8364,6 +8364,8 @@ struct trace_array *trace_array_create(const char *name)
>>
>> list_add(&tr->list, &ftrace_trace_arrays);
>>
>> + tr->ref++;
>> +
> Needs a comment for why the ref is incremented.
>
>
>> mutex_unlock(&trace_types_lock);
>> mutex_unlock(&event_mutex);
>>
>> @@ -8385,7 +8387,14 @@ struct trace_array *trace_array_create(const char *name)
>>
>> static int instance_mkdir(const char *name)
>> {
>> - return PTR_ERR_OR_ZERO(trace_array_create(name));
>> + struct trace_array *tr;
>> +
>> + tr = trace_array_create(name);
>> + if (IS_ERR(tr))
>> + return PTR_ERR(tr);
>> + trace_array_put(tr);
> Need a comment to why we need to do a put here.
>
>> +
>> + return 0;
>> }
>>
>> static int __remove_instance(struct trace_array *tr)
>> @@ -8434,6 +8443,7 @@ int trace_array_destroy(struct trace_array *tr)
>> mutex_lock(&event_mutex);
>> mutex_lock(&trace_types_lock);
>>
>> + tr->ref--;
>> ret = __remove_instance(tr);
>>
>> mutex_unlock(&trace_types_lock);
>> @@ -8465,6 +8475,24 @@ static int instance_rmdir(const char *name)
>> return ret;
>> }
>>
> Need a kerneldoc heading here, that also states that if a trace_array
> is returned, it requires a call to trace_array_put().
>
>
>> +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 445b059..c126d2c 100644
>> --- a/kernel/trace/trace_events.c
>> +++ b/kernel/trace/trace_events.c
>> @@ -859,6 +859,28 @@ 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 -ENODEV;
> If we have this, should we get rid of the external use of
> ftrace_set_clr_event()?
I think so too. External use of trace_array_set_clr_event is more
convenient and intuitive. Will make the change.
Thanks,
Divya
>
> -- Steve
>
>> +
>> + 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
>>