From patchwork Tue Nov 27 15:42:24 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Tzvetomir Stoyanov X-Patchwork-Id: 10759915 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 S1729862AbeK1Ckw (ORCPT ); Tue, 27 Nov 2018 21:40:52 -0500 From: Tzvetomir Stoyanov To: "rostedt@goodmis.org" CC: "linux-trace-devel@vger.kernel.org" Subject: [PATCH v3 14/46] tools/lib/traceevent: Man pages for tep_register_event_handler() and tep_unregister_event_handler() Date: Tue, 27 Nov 2018 15:42:24 +0000 Message-ID: <20181127154153.11315-15-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: 5711 Create man pages for tep_register_event_handler() and tep_unregister_event_handler() as part of the libtraceevent APIs. Signed-off-by: Tzvetomir Stoyanov --- .../libtraceevent-reg_event_handler.txt | 129 ++++++++++++++++++ 1 file changed, 129 insertions(+) create mode 100644 tools/lib/traceevent/Documentation/libtraceevent-reg_event_handler.txt diff --git a/tools/lib/traceevent/Documentation/libtraceevent-reg_event_handler.txt b/tools/lib/traceevent/Documentation/libtraceevent-reg_event_handler.txt new file mode 100644 index 000000000000..ee9aa3a4151b --- /dev/null +++ b/tools/lib/traceevent/Documentation/libtraceevent-reg_event_handler.txt @@ -0,0 +1,129 @@ +libtraceevent(3) +================ + +NAME +---- +tep_register_event_handler,tep_unregister_event_handler - Register / unregisters +a callback function to parse an event information. + +SYNOPSIS +-------- +[verse] +-- +*#include * + +enum *tep_reg_handler* { + _TEP_REGISTER_SUCCESS_, + _TEP_REGISTER_SUCCESS_OVERWRITE_, +}; + +int *tep_register_event_handler*(struct tep_handle pass:[*]_tep_, int _id_, const char pass:[*]_sys_name_, const char pass:[*]_event_name_, tep_event_handler_func _func_, void pass:[*]_context_); +int *tep_unregister_event_handler*(struct tep_handle pass:[*]tep, int id, const char pass:[*]sys_name, const char pass:[*]event_name, tep_event_handler_func func, void pass:[*]_context_); + +typedef int (*pass:[*]tep_event_handler_func*)(struct trace_seq pass:[*]s, struct tep_record pass:[*]record, struct tep_event pass:[*]event, void pass:[*]context); +-- + +DESCRIPTION +----------- +The _tep_register_event_handler()_ function registers a handler function, +which is going to be called to parse the information for a given event. +The _tep_ argument is the trace event parser context. The _id_ argument is +the id of the event. The _sys_name_ argument is the name of the system, +the event belongs to. The _event_name_ argument is the name of the event. +If _id_ is >= 0, it is used to find the event, otherwise _sys_name_ and +_event_name_ are used. The _func_ is a pointer to the function, which is going +to be called to parse the event information. The _context_ argument is a pointer +to the context data, which will be passed to the _func_. If a handler function +for the same event is already registered, it will be overridden with the new +one. This mechanism allows a developer to override the parsing of a given event. +If for some reason the default print format is not sufficient, the developer +can register a function for an event to be used to parse the data instead. + +The _tep_unregister_event_handler()_ function unregisters the handler function, +previously registered with _tep_register_event_handler()_. The _tep_ argument +is the trace event parser context. The _id_, _sys_name_, _event_name_, _func_, +and _context_ are the same arguments, as when the callback function _func_ was +registered. + +The _tep_event_handler_func_ is the type of the custom event handler +function. The _s_ argument is the trace sequence, it can be used to create a +custom string, describing the event. A _record_ to get the event from is passed +as input parameter and also the _event_ - the handle to the record's event. The +_context_ is custom context, set when the custom event handler is registered. + +RETURN VALUE +------------ +The _tep_register_event_handler()_ function returns _TEP_REGISTER_SUCCESS_ +if the new handler is registered successfully or _TEP_REGISTER_SUCCESS_OVERWRITE_ if +an existing handler is overwritten. If there is not enough memory to complete +the registration, TEP_ERRNO__MEM_ALLOC_FAILED is returned. + +The _tep_unregister_event_handler()_ function returns 0 if _func_ was removed +successful or, -1 if the event was not found. + +The _tep_event_handler_func_ should return -1 in case of an error, or 0 otherwise. + +EXAMPLE +------- +[source,c] +-- +#include +#include +... +struct tep_handle *tep = tep_alloc(); +... +int custom_event_handler(struct trace_seq *s, struct tep_record *record, + struct tep_event *event, void *context) +{ + trace_seq_printf(s, "kvm_exit event"); + return 0; +} +... + if (tep_register_event_handler(tep, -1, "kvm", "kvm_exit", + custom_event_handler, NULL)) { + /* Failed to register the handler for event "kvm_exit" from "kvm" system */ + } +... + if (tep_unregister_event_handler(pevent, -1, "kvm", "kvm_exit", + custom_event_handler, NULL) != ) { + /* Failed to unregister the handler for event "kvm_exit" from "kvm" system */ + } + +-- + +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