On Mon, 12 Apr 2021 18:20:06 +0300
"Yordan Karadzhov (VMware)" <y.karadz@xxxxxxxxx> wrote:
> @@ -364,19 +384,34 @@ static int write_file(const char *file, const char *str)
> int tracefs_instance_file_write(struct tracefs_instance *instance,
> const char *file, const char *str)
> {
> - struct stat st;
> - char *path;
> - int ret;
> + return instance_file_write(instance, file, str, O_WRONLY | O_TRUNC);
> +}
>
> - path = tracefs_instance_get_file(instance, file);
> - if (!path)
> - return -1;
> - ret = stat(path, &st);
> - if (ret == 0)
> - ret = write_file(path, str);
> - tracefs_put_tracing_file(path);
> +/**
> + * tracefs_instance_file_write - Append to a trace file of specific instance.
I think you meant "tracefs_instance_file_append - "
> + * @instance: ftrace instance, can be NULL for the top instance
> + * @file: name of the file
> + * @str: nul terminated string, that will be appended to the file.
> + *
> + * Returns the number of appended bytes, or -1 in case of an error.
> + */
> +int tracefs_instance_file_append(struct tracefs_instance *instance,
> + const char *file, const char *str)
> +{
> + return instance_file_write(instance, file, str, O_WRONLY);
> +}
>
> - return ret;
> +/**
> + * tracefs_instance_file_write - Clear a trace file of specific instance.
And "tracefs_instance_file_clear - "
> + * @instance: ftrace instance, can be NULL for the top instance
> + * @file: name of the file
"of the file to clear"
More comments should be in the body.
"Used to clear the file. Note, it only opens with O_TRUNC and closes the
file. If the file has content that does not get cleared in this way, this
will not have any effect. For example, set_ftrace_filter can have probes
that are not cleared by O_TRUNC:
echo "schedule:stacktrace" > set_ftrace_filter
This function will not clear the above "set_ftrace_filter" after that
command."
> + *
> + * Returns 0 on success, or -1 in case of an error.
> + */
> +int tracefs_instance_file_clear(struct tracefs_instance *instance,
> + const char *file)
> +{
> + return instance_file_write(instance, file, NULL, O_WRONLY | O_TRUNC);
> }
>
> /**
Other than that, it looks good.
-- Steve
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