From patchwork Tue Nov 27 15:42:27 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Tzvetomir Stoyanov X-Patchwork-Id: 10759917 Return-Path: Received: from mail-eopbgr730068.outbound.protection.outlook.com ([40.107.73.68]:47354 "EHLO NAM05-DM3-obe.outbound.protection.outlook.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1729913AbeK1Ckx (ORCPT ); Tue, 27 Nov 2018 21:40:53 -0500 From: Tzvetomir Stoyanov To: "rostedt@goodmis.org" CC: "linux-trace-devel@vger.kernel.org" Subject: [PATCH v3 16/46] tools/lib/traceevent: Man pages for tep_register_print_function() and tep_unregister_print_function() Date: Tue, 27 Nov 2018 15:42:27 +0000 Message-ID: <20181127154153.11315-17-tstoyanov@vmware.com> References: <20181127154153.11315-1-tstoyanov@vmware.com> In-Reply-To: <20181127154153.11315-1-tstoyanov@vmware.com> Content-Language: en-US MIME-Version: 1.0 Sender: linux-trace-devel-owner@vger.kernel.org List-ID: Content-Length: 4804 Create man pages for tep_register_print_function() and tep_unregister_print_function() as part of the libtraceevent APIs. Signed-off-by: Tzvetomir Stoyanov --- .../libtraceevent-reg_print_func.txt | 128 ++++++++++++++++++ 1 file changed, 128 insertions(+) create mode 100644 tools/lib/traceevent/Documentation/libtraceevent-reg_print_func.txt diff --git a/tools/lib/traceevent/Documentation/libtraceevent-reg_print_func.txt b/tools/lib/traceevent/Documentation/libtraceevent-reg_print_func.txt new file mode 100644 index 000000000000..fbb2f973f3b0 --- /dev/null +++ b/tools/lib/traceevent/Documentation/libtraceevent-reg_print_func.txt @@ -0,0 +1,128 @@ +libtraceevent(3) +================ + +NAME +---- +tep_register_print_function,tep_unregister_print_function - Registers / Unregisters +a helper function. + +SYNOPSIS +-------- +[verse] +-- +*#include * + +enum *tep_func_arg_type* { + TEP_FUNC_ARG_VOID, + TEP_FUNC_ARG_INT, + TEP_FUNC_ARG_LONG, + TEP_FUNC_ARG_STRING, + TEP_FUNC_ARG_PTR, + TEP_FUNC_ARG_MAX_TYPES +}; + +typedef unsigned long long (*pass:[*]tep_func_handler*)(struct trace_seq pass:[*]s, unsigned long long pass:[*]args); + +int *tep_register_print_function*(struct tep_handle pass:[*]_tep_, tep_func_handler _func_, enum tep_func_arg_type _ret_type_, char pass:[*]_name_, _..._); +int *tep_unregister_print_function*(struct tep_handle pass:[*]_tep_, tep_func_handler _func_, char pass:[*]_name_); +-- + +DESCRIPTION +----------- +Some events may have helper functions in the print format arguments. This allows +a plugin to dynamically create a way to process one of these functions. + +The _tep_register_print_function()_ registers such helper function. The _tep_ +argument is the trace event parser context. The _func_ argument is the address +of the helper function. The _ret_type_ argument is the return type of the +helper function, value from the _tep_func_arg_type_ enum. The _name_ is the name +of the helper function, as seen in the print format arguments. The _..._ is a +variable list of _tep_func_arg_type_ enums, the _func_ function arguments. +This list must end with _TEP_FUNC_ARG_VOID_. + +The _tep_unregister_print_function()_ unregisters a helper function, previously +registered with _tep_register_print_function()_. The _tep_ argument is the +trace event parser context. The _func_ and _name_ arguments are the same, used +when the helper function was registered. + +The _tep_func_handler_ is the type of the helper function. The _s_ argument is +the trace sequence, it can be used to create a custom string. +The _args_ is a list of arguments, defined when the helper function was +registered. + +RETURN VALUE +------------ +The _tep_register_print_function()_ function returns 0 in case of success. +In case of an error, TEP_ERRNO_... code is returned. + +The _tep_unregister_print_function()_ returns 0 in case of success, or -1 in +case of an error. + +EXAMPLE +------- +[source,c] +-- +#include +#include +... +struct tep_handle *tep = tep_alloc(); +... +static long long +process_custom_helper(struct trace_seq *s, unsigned long long *args) +{ + unsigned long long param = args[0]; + trace_seq_printf(s, "the helper was called, with argument %lld", param); + return 0; +} +... + if ( tep_register_print_function(tep, + process_custom_helper, + TEP_FUNC_ARG_STRING, + "custom_helper", + TEP_FUNC_ARG_LONG, + TEP_FUNC_ARG_VOID) != 0) { + /* Failed to register my process_custom_helper function */ + } +... + if (tep_unregister_print_function(tep, process_custom_helper, + "custom_helper") != 0) { + /* Failed to unregister my process_custom_helper function */ + } +-- + +FILES +----- +[verse] +-- +*event-parse.h* + Header file to include in order to have access to the library APIs. +*trace-seq.h* + Header file to include in order to have access to trace sequences related APIs. + Trace sequences are used to allow a function to call several other functions + to create a string of data to use. +*-ltraceevent* + Linker switch to add when building a program that uses the library. +-- + +SEE ALSO +-------- +_libtraceevent(3)_, _trace-cmd(1)_ + +AUTHOR +------ +[verse] +-- +*Steven Rostedt* , author of *libtraceevent*. +*Tzvetomir Stoyanov* , author of this man page. +-- +REPORTING BUGS +-------------- +Report bugs to + +LICENSE +------- +libtraceevent is Free Software licensed under the GNU LGPL 2.1 + +RESOURCES +--------- +https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git