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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 | // SPDX-License-Identifier: GPL-2.0-only /* * Copyright (C) 2021 Ahmad Fatoum, Pengutronix * Copyright (C) 2025 Linaro Limited * * An implementation of cooperative multi-tasking inspired from barebox threads * https://github.com/barebox/barebox/blob/master/common/bthread.c */ #include <compiler.h> #include <linux/errno.h> #include <linux/kernel.h> #include <linux/list.h> #include <malloc.h> #include <setjmp.h> #include <stdint.h> #include <uthread.h> static struct uthread main_thread = { .list = LIST_HEAD_INIT(main_thread.list), }; static struct uthread *current = &main_thread; /** * uthread_trampoline() - Call the current thread's entry point then resume the * main thread. * * This is a helper function which is used as the @func argument to the * initjmp() function, and ultimately invoked via setjmp(). It does not return * but instead longjmp()'s back to the main thread. */ static void __noreturn uthread_trampoline(void) { struct uthread *curr = current; curr->fn(curr->arg); curr->done = true; current = &main_thread; longjmp(current->ctx, 1); /* Not reached */ while (true) ; } /** * uthread_free() - Free memory used by a uthread object. */ static void uthread_free(struct uthread *uthread) { if (!uthread) return; free(uthread->stack); free(uthread); } int uthread_create(struct uthread *uthr, void (*fn)(void *), void *arg, size_t stack_sz, unsigned int grp_id) { bool user_allocated = false; if (!stack_sz) stack_sz = CONFIG_UTHREAD_STACK_SIZE; if (uthr) { user_allocated = true; } else { uthr = calloc(1, sizeof(*uthr)); if (!uthr) return -1; } uthr->stack = memalign(16, stack_sz); if (!uthr->stack) goto err; uthr->fn = fn; uthr->arg = arg; uthr->grp_id = grp_id; list_add_tail(&uthr->list, ¤t->list); initjmp(uthr->ctx, uthread_trampoline, uthr->stack, stack_sz); return 0; err: if (!user_allocated) free(uthr); return -1; } /** * uthread_resume() - switch execution to a given thread * * @uthread: the thread object that should be resumed */ static void uthread_resume(struct uthread *uthread) { if (!setjmp(current->ctx)) { current = uthread; longjmp(uthread->ctx, 1); } } bool uthread_schedule(void) { struct uthread *next; struct uthread *tmp; list_for_each_entry_safe(next, tmp, ¤t->list, list) { if (!next->done) { uthread_resume(next); return true; } /* Found a 'done' thread, free its resources */ list_del(&next->list); uthread_free(next); } return false; } unsigned int uthread_grp_new_id(void) { static unsigned int id; return ++id; } bool uthread_grp_done(unsigned int grp_id) { struct uthread *next; list_for_each_entry(next, &main_thread.list, list) { if (next->grp_id == grp_id && !next->done) return false; } return true; } int uthread_mutex_lock(struct uthread_mutex *mutex) { while (mutex->state == UTHREAD_MUTEX_LOCKED) uthread_schedule(); mutex->state = UTHREAD_MUTEX_LOCKED; return 0; } int uthread_mutex_trylock(struct uthread_mutex *mutex) { if (mutex->state == UTHREAD_MUTEX_UNLOCKED) { mutex->state = UTHREAD_MUTEX_LOCKED; return 0; } return -EBUSY; } int uthread_mutex_unlock(struct uthread_mutex *mutex) { mutex->state = UTHREAD_MUTEX_UNLOCKED; return 0; } |