From a1998897f66858ec7d2d184e98f2be1e46ae2d78 Mon Sep 17 00:00:00 2001 From: Matt Caswell Date: Wed, 19 Jun 2019 10:31:39 +0100 Subject: [PATCH] Add some internal documentation for some thread related functions Reviewed-by: Richard Levitte (Merged from https://github.com/openssl/openssl/pull/9186) --- .../man3/ossl_init_thread_deregister.pod | 64 +++++++++++++++++++ 1 file changed, 64 insertions(+) create mode 100644 doc/internal/man3/ossl_init_thread_deregister.pod diff --git a/doc/internal/man3/ossl_init_thread_deregister.pod b/doc/internal/man3/ossl_init_thread_deregister.pod new file mode 100644 index 0000000000..4481d0c2e2 --- /dev/null +++ b/doc/internal/man3/ossl_init_thread_deregister.pod @@ -0,0 +1,64 @@ +=pod + +=head1 NAME +OSSL_thread_stop_handler_fn, +ossl_init_thread_start, +ossl_init_thread_deregister +- internal thread routines +=head1 SYNOPSIS + + #include "internal/cryptlib_int.h" + #include + + typedef void (*OSSL_thread_stop_handler_fn)(void *arg); + + int ossl_init_thread_start(const void *index, void *arg, + OSSL_thread_stop_handler_fn handfn); + int ossl_init_thread_deregister(void *index); + +=head1 DESCRIPTION + +Thread aware code may be informed about when a thread is stopping, typically to +perform some cleanup operation. +Thread stop events may be detected by OpenSSL either automatically (using the +capabilities of the underlying threading library) where possible or explicitly +by the application calling OPENSSL_thread_stop() or OPENSSL_thread_stop_ex(). + +Thread aware code registers a "stop handler" for each new thread that it uses. +Typically, when a new thread is being used, code will add a new value to some +thread local variable and then register a stop handler. When the thread is +stopping the stop handler is called (while on that thread) and the code can +clean up the value stored in the thread local variable. + +A new stop handler is registerd using the function ossl_init_thread_start(). +The B parameter should be a unique value that can be used to identify a +set of common stop handlers and is passed in a later call to +ossl_init_thread_deregister. If no later call to ossl_init_thread_deregister is +made then NULL can be passed for this parameter. The B parameter is passed +back as an argument to the stop handler when it is later invoked. Finally the +B is a function pointer to the stop handler itself. + +In the event that previously registered stop handlers need to be deregistered +then this can be done using the function ossl_init_thread_deregister(). +This will deregister all stop handlers (no matter which thread they were +registered for) which the same B value. + +=head1 RETURN VALUES + +ossl_init_thread_start() and ossl_init_thread_deregister() return 1 for success +or 0 on error. + +=head1 HISTORY + +The functions described here were all added in OpenSSL 3.0. + +=head1 COPYRIGHT + +Copyright 2019 The OpenSSL Project Authors. All Rights Reserved. + +Licensed under the Apache License 2.0 (the "License"). You may not use +this file except in compliance with the License. You can obtain a copy +in the file LICENSE in the source distribution or at +L. + +=cut -- 2.25.1