On Thu, Apr 8, 2021 at 1:02 AM Steven Rostedt <rostedt@xxxxxxxxxxx> wrote:
>
> From: "Steven Rostedt (VMware)" <rostedt@xxxxxxxxxxx>
>
> Add the API of tracefs_function_notrace() that is identical to how
> tracefs_function_filter() works, but will work with the set_ftrace_notrace
> filter file.
>
> Signed-off-by: Steven Rostedt (VMware) <rostedt@xxxxxxxxxxx>
> ---
> Documentation/libtracefs-function-filter.txt | 19 ++++++++---
> include/tracefs-local.h | 1 +
> include/tracefs.h | 3 ++
> src/tracefs-instance.c | 1 +
> src/tracefs-tools.c | 33 ++++++++++++++++++++
> 5 files changed, 53 insertions(+), 4 deletions(-)
>
> diff --git a/Documentation/libtracefs-function-filter.txt b/Documentation/libtracefs-function-filter.txt
> index ccf20e9..746be37 100644
> --- a/Documentation/libtracefs-function-filter.txt
> +++ b/Documentation/libtracefs-function-filter.txt
> @@ -4,6 +4,7 @@ libtracefs(3)
> NAME
> ----
> tracefs_function_filter - Function to limit kernel functions that are traced
> +tracefs_function_notrace - Function to filter kernel functions that not to be traced
>
> SYNOPSIS
> --------
> @@ -12,15 +13,18 @@ SYNOPSIS
> *#include <tracefs.h>*
>
> int *tracefs_function_filter*(struct tracefs_instance pass:[*]_instance_, const char pass:[*]_filter_, const char pass:[*]_module_, int _flags_);
> +int *tracefs_function_notrace*(struct tracefs_instance pass:[*]_instance_, const char pass:[*]_filter_, const char pass:[*]_module_, int _flags_);
> --
>
> DESCRIPTION
> -----------
> -This function can be used to limit the Linux kernel functions that would be
> -traced by the function and function-graph tracers
> +*tracefs_function_filter* and *tracefs_function_notrace* can be used to limit the
> +Linux kernel functions that would be traced by the function and function-graph tracers.
> +The *tracefs_function_filter* defines a list of functions that can be traced.
> +The *tracefs_function_notrace* defines a list of functions that will not be traced.
> +If a function is in both lists, it will not be traced.
>
> -It will take an
> -_instance_ , that can be NULL for the top level tracing,
> +They take an _instance_ , that can be NULL for the top level tracing,
> _filter_, a string that represents a filter that should
> be applied to define what functions are to be traced,
> _module_, to limit the filtering on a specific module (or NULL to filter on all functions),
> @@ -125,6 +129,13 @@ int main(int argc, char *argv[])
> /* Error creating new trace instance */
> }
>
> + /* Do not trace any function with the word "lock" in it */
> + ret = tracefs_function_notrace(inst, "*lock*", NULL, TRACEFS_FL_RESET);
> + if (ret) {
> + printf("Failed to set the notrace filter\n");
> + goto out;
> + }
> +
> /* First reset the filter */
> ret = tracefs_function_filter(inst, NULL, NULL,
> TRACEFS_FL_RESET | TRACEFS_FL_CONTINUE);
> diff --git a/include/tracefs-local.h b/include/tracefs-local.h
> index 73ec113..060de7e 100644
> --- a/include/tracefs-local.h
> +++ b/include/tracefs-local.h
> @@ -19,6 +19,7 @@ struct tracefs_instance {
> char *name;
> int flags;
> int ftrace_filter_fd;
> + int ftrace_notrace_fd;
> };
>
> /* Can be overridden */
> diff --git a/include/tracefs.h b/include/tracefs.h
> index befcc48..70b7ebe 100644
> --- a/include/tracefs.h
> +++ b/include/tracefs.h
> @@ -160,4 +160,7 @@ enum {
>
> int tracefs_function_filter(struct tracefs_instance *instance, const char *filter,
> const char *module, unsigned int flags);
> +int tracefs_function_notrace(struct tracefs_instance *instance, const char *filter,
> + const char *module, unsigned int flags);
> +
> #endif /* _TRACE_FS_H */
> diff --git a/src/tracefs-instance.c b/src/tracefs-instance.c
> index bf2fabf..9f45624 100644
> --- a/src/tracefs-instance.c
> +++ b/src/tracefs-instance.c
> @@ -44,6 +44,7 @@ static struct tracefs_instance *instance_alloc(const char *trace_dir, const char
> }
>
> instance->ftrace_filter_fd = -1;
> + instance->ftrace_notrace_fd = -1;
These descriptors should be closed in tracefs_instance_free(), as part
of the instance cleanup.
>
> return instance;
>
> diff --git a/src/tracefs-tools.c b/src/tracefs-tools.c
> index 21a9bd3..b41806b 100644
> --- a/src/tracefs-tools.c
> +++ b/src/tracefs-tools.c
> @@ -21,10 +21,12 @@
>
> #define TRACE_CTRL "tracing_on"
> #define TRACE_FILTER "set_ftrace_filter"
> +#define TRACE_NOTRACE "set_ftrace_notrace"
> #define TRACE_FILTER_LIST "available_filter_functions"
>
> /* File descriptor for Top level set_ftrace_filter */
> static int ftrace_filter_fd = -1;
> +static int ftrace_notrace_fd = -1;
> static pthread_mutex_t filter_lock = PTHREAD_MUTEX_INITIALIZER;
I'm wondering if we should free these global resources somehow. A
cleanup API for the whole library can be implemented using
__attribute__((destructor)), or some other way ?
>
> static const char * const options_map[] = {
> @@ -898,3 +900,34 @@ int tracefs_function_filter(struct tracefs_instance *instance, const char *filte
> tracefs_put_tracing_file(filter_path);
> return ret;
> }
> +
> +/**
> + * tracefs_function_notrace - filter the functions that are not to be traced
> + * @instance: ftrace instance, can be NULL for top tracing instance.
> + * @filter: The filter to filter what functions are not to be traced
> + * @module: Module to be traced or NULL if all functions are to be examined.
> + * @flags: flags on modifying the filter file
> + *
> + * See tracefs_function_filter, as this has the same functionality but
> + * for adding to the "notrace" filter.
> + */
> +int tracefs_function_notrace(struct tracefs_instance *instance, const char *filter,
> + const char *module, unsigned int flags)
> +{
> + char *filter_path;
> + int *fd;
> + int ret;
> +
> + filter_path = tracefs_instance_get_file(instance, TRACE_NOTRACE);
> + if (!filter_path)
> + return -1;
> +
> + if (instance)
> + fd = &instance->ftrace_notrace_fd;
> + else
> + fd = &ftrace_notrace_fd;
> +
> + ret = update_filter(filter_path, fd, instance, filter, module, flags);
> + tracefs_put_tracing_file(filter_path);
> + return ret;
> +}
> --
> 2.29.2
>
--
Tzvetomir (Ceco) Stoyanov
VMware Open Source Technology Center
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