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bh=mGA6rsT/KoVVUbrj1wwe4PQ9R01YvHM/Rme9TDGvRzQ=; b=njaHQq9Y+lgf1H5/DcxzBWpLkfVTU7qmpse278jUM/5LwMiqUc5PKH6ICae3A8R1lt iyhbJPKGPlphGTKCgt3INBgYg90e/RA6C0UTwyp/JKQu145lb7/qAML4MvQ5tZH7YfmC 4goyi4uYmiJdDHB/rj45Bmh6DuZhKuKlpPJOZcLAsbkCHtmVM1woW02PLgWtcO6uE761 naFJc2vDaLJxaxGPDAWHD1JL9Lq/HckHflcy5CYdnK7DYaV2cG6aTyYeReCYBLgHLhmb 8a/lMxkc1iN2i7sk7qq0lkpHxY2lF4FlkpNGH1tt2P4DZpZZ08y/xbvz12mfeNYDeb3Q Pn7Q== X-Gm-Message-State: AOAM531JjHzmQ+jnR4Pi0r3HYCXJIbDI67OSjr2k2WDI6YGLxG3cX/he tWIOOEwsc3ZIIIVj6qsEGgMJFUMy73BfzA== X-Google-Smtp-Source: ABdhPJwUw8oJUl46wp1g7fh1hZm0qEKBNQPe4dzWukLS6ULZ7hcoE84UHYW9d0AY+5OVWuVRwVEwSQ== X-Received: by 2002:a17:903:31cc:b029:e4:bd48:c8e3 with SMTP id v12-20020a17090331ccb02900e4bd48c8e3mr4994589ple.40.1615994997952; Wed, 17 Mar 2021 08:29:57 -0700 (PDT) Received: from localhost.localdomain ([115.98.13.163]) by smtp.gmail.com with ESMTPSA id b22sm21605618pff.173.2021.03.17.08.29.55 (version=TLS1_2 cipher=ECDHE-ECDSA-AES128-GCM-SHA256 bits=128/128); Wed, 17 Mar 2021 08:29:57 -0700 (PDT) From: Sameeruddin shaik To: rostedt@goodmis.org Cc: linux-trace-devel@vger.kernel.org, Sameeruddin shaik Subject: [PATCH v2] libtracefs: An API to set the filtering of functions Date: Thu, 18 Mar 2021 21:00:17 +0530 Message-Id: <1616081417-4107-1-git-send-email-sameeruddin.shaik8@gmail.com> X-Mailer: git-send-email 2.7.4 Precedence: bulk List-ID: X-Mailing-List: linux-trace-devel@vger.kernel.org This new API will write the function filters into the set_ftrace_filter file. tracefs_function_filter() https://bugzilla.kernel.org/show_bug.cgi?id=210643 Signed-off-by: Sameeruddin shaik --- Error handling is addressed as per the comments if filters[i] is not NULL, then only we are going inside for loop, at the asprintf i think it won't be necessary to check the filters[i] is NULL or not again, when it throws error, if i am wrong please correct me. diff --git a/include/tracefs.h b/include/tracefs.h index f3eec62..c1f07b0 100644 --- a/include/tracefs.h +++ b/include/tracefs.h @@ -145,5 +145,6 @@ bool tracefs_option_is_enabled(struct tracefs_instance *instance, enum tracefs_o int tracefs_option_enable(struct tracefs_instance *instance, enum tracefs_option_id id); int tracefs_option_diasble(struct tracefs_instance *instance, enum tracefs_option_id id); const char *tracefs_option_name(enum tracefs_option_id id); - +int tracefs_function_filter(struct tracefs_instance *instance, const char **filters, + const char *module, bool reset, const char ***errs); #endif /* _TRACE_FS_H */ diff --git a/src/tracefs-tools.c b/src/tracefs-tools.c index e2dfc7b..ca6077b 100644 --- a/src/tracefs-tools.c +++ b/src/tracefs-tools.c @@ -18,6 +18,7 @@ #include "tracefs-local.h" #define TRACE_CTRL "tracing_on" +#define TRACE_FILTER "set_ftrace_filter" static const char * const options_map[] = { "unknown", @@ -387,3 +388,108 @@ void tracefs_option_clear(struct tracefs_options_mask *options, enum tracefs_opt if (options && id > TRACEFS_OPTION_INVALID) options->mask &= ~(1ULL << (id - 1)); } + +static int controlled_write(const char *filter_path, const char **filters, + const char *module, bool reset, const char ***errs) +{ + int flags = reset ? O_TRUNC : O_APPEND; + const char **e = NULL; + char *each_str = NULL; + int write_size = 0; + int size = 0; + int fd = -1; + int ret = 0; + int j = 0; + int i; + + fd = open(filter_path, O_WRONLY | flags); + if (fd < 0) + return 1; + + for (i = 0; filters[i]; i++) { + if (module) + write_size = asprintf(&each_str, "%s:mod:%s ", filters[i], module); + else + write_size = asprintf(&each_str, "%s ", filters[i]); + if (write_size < 0) { + ret = 1; + goto error; + } + size = write(fd, each_str, write_size); + /* compare written bytes*/ + if (size < write_size) { + if (errs) { + e = realloc(e, (j + 1) * (sizeof(char *))); + if (!e) { + ret = 1; + goto error; + } + e[j++] = filters[i]; + ret -= 1; + } + } + free(each_str); + each_str = NULL; + } + if (errs) { + e = realloc(e, (j + 1) * (sizeof(char *))); + if (!e) { + free(e); + ret = 1; + goto error; + } + e[j] = NULL; + *errs = e; + } + error: + if (each_str) + free(each_str); + close(fd); + return ret; +} + +/** + * tracefs_function_filter - write to set_ftrace_filter file to trace + * particular functions + * @instance: ftrace instance, can be NULL for top tracing instance + * @filters: An array of function names ending with a NULL pointer + * @module: Module to be traced + * @reset: set to true to reset the file before applying the filter + * @errs: A pointer to array of constant strings that will be allocated + * on negative return of this function, pointing to the filters that + * failed.May be NULL, in which case this field will be ignored. + * + * The @filters is an array of strings, where each string will be used + * to set a function or functions to be traced. + * + * If @reset is true, then all functions in the filter are cleared + * before adding functions from @filters. Otherwise, the functions set + * by @filters will be appended to the filter file + * + * returns -x on filter errors (where x is number of failed filter + * srtings) and if @errs is not NULL will be an allocated string array + * pointing to the strings in @filters that failed and must be freed + * with free(). + * + * returns 1 on general errors not realted to setting the filter. + * @errs is not set even if supplied. + * + * return 0 on success and @errs is not set. + */ +int tracefs_function_filter(struct tracefs_instance *instance, const char **filters, + const char *module, bool reset, const char ***errs) +{ + char *ftrace_filter_path; + int ret = 0; + + if (!filters) + return 1; + + ftrace_filter_path = tracefs_instance_get_file(instance, TRACE_FILTER); + if (!ftrace_filter_path) + return 1; + + ret = controlled_write(ftrace_filter_path, filters, module, reset, errs); + tracefs_put_tracing_file(ftrace_filter_path); + return ret; +} -- 2.7.4