/* The tunable framework. See the README to know how to use the tunable in a glibc module. Copyright (C) 2016-2023 Free Software Foundation, Inc. This file is part of the GNU C Library. The GNU C Library is free software; you can redistribute it and/or modify it under the terms of the GNU Lesser General Public License as published by the Free Software Foundation; either version 2.1 of the License, or (at your option) any later version. The GNU C Library is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more details. You should have received a copy of the GNU Lesser General Public License along with the GNU C Library; if not, see . */ #ifndef _TUNABLES_H_ #define _TUNABLES_H_ #include #include #include typedef intmax_t tunable_num_t; typedef union { tunable_num_t numval; const char *strval; } tunable_val_t; typedef void (*tunable_callback_t) (tunable_val_t *); /* Full name for a tunable is top_ns.tunable_ns.id. */ #define TUNABLE_NAME_S(top,ns,id) #top "." #ns "." #id #define TUNABLE_ENUM_NAME(__top,__ns,__id) TUNABLE_ENUM_NAME1 (__top,__ns,__id) #define TUNABLE_ENUM_NAME1(__top,__ns,__id) __top ## _ ## __ns ## _ ## __id #include "dl-tunable-list.h" extern void __tunables_init (char **); extern void __tunables_print (void); extern bool __tunable_is_initialized (tunable_id_t); extern void __tunable_get_val (tunable_id_t, void *, tunable_callback_t); extern void __tunable_set_val (tunable_id_t, tunable_val_t *, tunable_num_t *, tunable_num_t *); extern void __tunable_get_default (tunable_id_t id, void *valp); rtld_hidden_proto (__tunables_init) rtld_hidden_proto (__tunables_print) rtld_hidden_proto (__tunable_is_initialized) rtld_hidden_proto (__tunable_get_val) rtld_hidden_proto (__tunable_set_val) rtld_hidden_proto (__tunable_get_default) /* Define TUNABLE_GET and TUNABLE_SET in short form if TOP_NAMESPACE and TUNABLE_NAMESPACE are defined. This is useful shorthand to get and set tunables within a module. */ #if defined TOP_NAMESPACE && defined TUNABLE_NAMESPACE # define TUNABLE_IS_INITIALIZED(__id) \ TUNABLE_IS_INITIALIZED_FULL(TOP_NAMESPACE, TUNABLE_NAMESPACE, __id) # define TUNABLE_GET_DEFAULT(__id, __type) \ TUNABLE_GET_DEFAULT_FULL(TOP_NAMESPACE, TUNABLE_NAMESPACE,__id, __type) # define TUNABLE_GET(__id, __type, __cb) \ TUNABLE_GET_FULL (TOP_NAMESPACE, TUNABLE_NAMESPACE, __id, __type, __cb) # define TUNABLE_SET(__id, __val) \ TUNABLE_SET_FULL (TOP_NAMESPACE, TUNABLE_NAMESPACE, __id, __val) # define TUNABLE_SET_WITH_BOUNDS(__id, __val, __min, __max) \ TUNABLE_SET_WITH_BOUNDS_FULL (TOP_NAMESPACE, TUNABLE_NAMESPACE, __id, \ __val, __min, __max) #else # define TUNABLE_IS_INITIALIZED(__top, __ns, __id) \ TUNABLE_IS_INITIALIZED_FULL(__top, __ns, __id) # define TUNABLE_GET_DEFAULT(__top, __ns, __type) \ TUNABLE_GET_DEFAULT_FULL(__top, __ns, __id, __type) # define TUNABLE_GET(__top, __ns, __id, __type, __cb) \ TUNABLE_GET_FULL (__top, __ns, __id, __type, __cb) # define TUNABLE_SET(__top, __ns, __id, __val) \ TUNABLE_SET_FULL (__top, __ns, __id, __val) # define TUNABLE_SET_WITH_BOUNDS(__top, __ns, __id, __val, __min, __max) \ TUNABLE_SET_WITH_BOUNDS_FULL (__top, __ns, __id, __val, __min, __max) #endif /* Return whether the tunable was initialized by the environment variable. */ #define TUNABLE_IS_INITIALIZED_FULL(__top, __ns, __id) \ ({ \ tunable_id_t id = TUNABLE_ENUM_NAME (__top, __ns, __id); \ __tunable_is_initialized (id); \ }) /* Return the default value of the tunable. */ #define TUNABLE_GET_DEFAULT_FULL(__top, __ns, __id, __type) \ ({ \ tunable_id_t id = TUNABLE_ENUM_NAME (__top, __ns, __id); \ __type __ret; \ __tunable_get_default (id, &__ret); \ __ret; \ }) /* Get and return a tunable value. If the tunable was set externally and __CB is defined then call __CB before returning the value. */ #define TUNABLE_GET_FULL(__top, __ns, __id, __type, __cb) \ ({ \ tunable_id_t id = TUNABLE_ENUM_NAME (__top, __ns, __id); \ __type ret; \ __tunable_get_val (id, &ret, __cb); \ ret; \ }) /* Set a tunable value. */ #define TUNABLE_SET_FULL(__top, __ns, __id, __val) \ ({ \ __tunable_set_val (TUNABLE_ENUM_NAME (__top, __ns, __id), \ & (tunable_val_t) {.numval = __val}, NULL, NULL); \ }) /* Set a tunable value together with min/max values. */ #define TUNABLE_SET_WITH_BOUNDS_FULL(__top, __ns, __id,__val, __min, __max) \ ({ \ __tunable_set_val (TUNABLE_ENUM_NAME (__top, __ns, __id), \ & (tunable_val_t) {.numval = __val}, \ & (tunable_num_t) {__min}, \ & (tunable_num_t) {__max}); \ }) /* Namespace sanity for callback functions. Use this macro to keep the namespace of the modules clean. */ #define TUNABLE_CALLBACK(__name) _dl_tunable_ ## __name static __always_inline bool tunable_val_lt (tunable_num_t lhs, tunable_num_t rhs, bool unsigned_cmp) { if (unsigned_cmp) return (uintmax_t) lhs < (uintmax_t) rhs; else return lhs < rhs; } static __always_inline bool tunable_val_gt (tunable_num_t lhs, tunable_num_t rhs, bool unsigned_cmp) { if (unsigned_cmp) return (uintmax_t) lhs > (uintmax_t) rhs; else return lhs > rhs; } /* Compare two name strings, bounded by the name hardcoded in glibc. */ static __always_inline bool tunable_is_name (const char *orig, const char *envname) { for (;*orig != '\0' && *envname != '\0'; envname++, orig++) if (*orig != *envname) break; /* The ENVNAME is immediately followed by a value. */ if (*orig == '\0' && *envname == '=') return true; else return false; } #endif