coroutine: move into libqemuutil.a library

The coroutine files are currently referenced by the block-obj-y
variable. The coroutine functionality though is already used by
more than just the block code. eg migration code uses coroutine
yield. In the future the I/O channel code will also use the
coroutine yield functionality. Since the coroutine code is nicely
self-contained it can be easily built as part of the libqemuutil.a
library, making it widely available.

The headers are also moved into include/qemu, instead of the
include/block directory, since they are now part of the util
codebase, and the impl was never in the block/ directory
either.

Signed-off-by: Daniel P. Berrange <berrange@redhat.com>

1 files changed, 0 insertions, 293 deletions

diff --git a/coroutine-sigaltstack.c b/coroutine-sigaltstack.c
deleted file mode 100644
index 63519fffc7..0000000000
--- a/coroutine-sigaltstack.c
+++ /dev/null
@@ -1,293 +0,0 @@
-/*
- * sigaltstack coroutine initialization code
- *
- * Copyright (C) 2006  Anthony Liguori <anthony@codemonkey.ws>
- * Copyright (C) 2011  Kevin Wolf <kwolf@redhat.com>
- * Copyright (C) 2012  Alex Barcelo <abarcelo@ac.upc.edu>
-** This file is partly based on pth_mctx.c, from the GNU Portable Threads
-**  Copyright (c) 1999-2006 Ralf S. Engelschall <rse@engelschall.com>
- *
- * This 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.
- *
- * This 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 this library; if not, see <http://www.gnu.org/licenses/>.
- */
-
-/* XXX Is there a nicer way to disable glibc's stack check for longjmp? */
-#ifdef _FORTIFY_SOURCE
-#undef _FORTIFY_SOURCE
-#endif
-#include <stdlib.h>
-#include <setjmp.h>
-#include <stdint.h>
-#include <pthread.h>
-#include <signal.h>
-#include "qemu-common.h"
-#include "block/coroutine_int.h"
-
-typedef struct {
-    Coroutine base;
-    void *stack;
-    sigjmp_buf env;
-} CoroutineUContext;
-
-/**
- * Per-thread coroutine bookkeeping
- */
-typedef struct {
-    /** Currently executing coroutine */
-    Coroutine *current;
-
-    /** The default coroutine */
-    CoroutineUContext leader;
-
-    /** Information for the signal handler (trampoline) */
-    sigjmp_buf tr_reenter;
-    volatile sig_atomic_t tr_called;
-    void *tr_handler;
-} CoroutineThreadState;
-
-static pthread_key_t thread_state_key;
-
-static CoroutineThreadState *coroutine_get_thread_state(void)
-{
-    CoroutineThreadState *s = pthread_getspecific(thread_state_key);
-
-    if (!s) {
-        s = g_malloc0(sizeof(*s));
-        s->current = &s->leader.base;
-        pthread_setspecific(thread_state_key, s);
-    }
-    return s;
-}
-
-static void qemu_coroutine_thread_cleanup(void *opaque)
-{
-    CoroutineThreadState *s = opaque;
-
-    g_free(s);
-}
-
-static void __attribute__((constructor)) coroutine_init(void)
-{
-    int ret;
-
-    ret = pthread_key_create(&thread_state_key, qemu_coroutine_thread_cleanup);
-    if (ret != 0) {
-        fprintf(stderr, "unable to create leader key: %s\n", strerror(errno));
-        abort();
-    }
-}
-
-/* "boot" function
- * This is what starts the coroutine, is called from the trampoline
- * (from the signal handler when it is not signal handling, read ahead
- * for more information).
- */
-static void coroutine_bootstrap(CoroutineUContext *self, Coroutine *co)
-{
-    /* Initialize longjmp environment and switch back the caller */
-    if (!sigsetjmp(self->env, 0)) {
-        siglongjmp(*(sigjmp_buf *)co->entry_arg, 1);
-    }
-
-    while (true) {
-        co->entry(co->entry_arg);
-        qemu_coroutine_switch(co, co->caller, COROUTINE_TERMINATE);
-    }
-}
-
-/*
- * This is used as the signal handler. This is called with the brand new stack
- * (thanks to sigaltstack). We have to return, given that this is a signal
- * handler and the sigmask and some other things are changed.
- */
-static void coroutine_trampoline(int signal)
-{
-    CoroutineUContext *self;
-    Coroutine *co;
-    CoroutineThreadState *coTS;
-
-    /* Get the thread specific information */
-    coTS = coroutine_get_thread_state();
-    self = coTS->tr_handler;
-    coTS->tr_called = 1;
-    co = &self->base;
-
-    /*
-     * Here we have to do a bit of a ping pong between the caller, given that
-     * this is a signal handler and we have to do a return "soon". Then the
-     * caller can reestablish everything and do a siglongjmp here again.
-     */
-    if (!sigsetjmp(coTS->tr_reenter, 0)) {
-        return;
-    }
-
-    /*
-     * Ok, the caller has siglongjmp'ed back to us, so now prepare
-     * us for the real machine state switching. We have to jump
-     * into another function here to get a new stack context for
-     * the auto variables (which have to be auto-variables
-     * because the start of the thread happens later). Else with
-     * PIC (i.e. Position Independent Code which is used when PTH
-     * is built as a shared library) most platforms would
-     * horrible core dump as experience showed.
-     */
-    coroutine_bootstrap(self, co);
-}
-
-Coroutine *qemu_coroutine_new(void)
-{
-    const size_t stack_size = 1 << 20;
-    CoroutineUContext *co;
-    CoroutineThreadState *coTS;
-    struct sigaction sa;
-    struct sigaction osa;
-    stack_t ss;
-    stack_t oss;
-    sigset_t sigs;
-    sigset_t osigs;
-    sigjmp_buf old_env;
-
-    /* The way to manipulate stack is with the sigaltstack function. We
-     * prepare a stack, with it delivering a signal to ourselves and then
-     * put sigsetjmp/siglongjmp where needed.
-     * This has been done keeping coroutine-ucontext as a model and with the
-     * pth ideas (GNU Portable Threads). See coroutine-ucontext for the basics
-     * of the coroutines and see pth_mctx.c (from the pth project) for the
-     * sigaltstack way of manipulating stacks.
-     */
-
-    co = g_malloc0(sizeof(*co));
-    co->stack = g_malloc(stack_size);
-    co->base.entry_arg = &old_env; /* stash away our jmp_buf */
-
-    coTS = coroutine_get_thread_state();
-    coTS->tr_handler = co;
-
-    /*
-     * Preserve the SIGUSR2 signal state, block SIGUSR2,
-     * and establish our signal handler. The signal will
-     * later transfer control onto the signal stack.
-     */
-    sigemptyset(&sigs);
-    sigaddset(&sigs, SIGUSR2);
-    pthread_sigmask(SIG_BLOCK, &sigs, &osigs);
-    sa.sa_handler = coroutine_trampoline;
-    sigfillset(&sa.sa_mask);
-    sa.sa_flags = SA_ONSTACK;
-    if (sigaction(SIGUSR2, &sa, &osa) != 0) {
-        abort();
-    }
-
-    /*
-     * Set the new stack.
-     */
-    ss.ss_sp = co->stack;
-    ss.ss_size = stack_size;
-    ss.ss_flags = 0;
-    if (sigaltstack(&ss, &oss) < 0) {
-        abort();
-    }
-
-    /*
-     * Now transfer control onto the signal stack and set it up.
-     * It will return immediately via "return" after the sigsetjmp()
-     * was performed. Be careful here with race conditions.  The
-     * signal can be delivered the first time sigsuspend() is
-     * called.
-     */
-    coTS->tr_called = 0;
-    pthread_kill(pthread_self(), SIGUSR2);
-    sigfillset(&sigs);
-    sigdelset(&sigs, SIGUSR2);
-    while (!coTS->tr_called) {
-        sigsuspend(&sigs);
-    }
-
-    /*
-     * Inform the system that we are back off the signal stack by
-     * removing the alternative signal stack. Be careful here: It
-     * first has to be disabled, before it can be removed.
-     */
-    sigaltstack(NULL, &ss);
-    ss.ss_flags = SS_DISABLE;
-    if (sigaltstack(&ss, NULL) < 0) {
-        abort();
-    }
-    sigaltstack(NULL, &ss);
-    if (!(oss.ss_flags & SS_DISABLE)) {
-        sigaltstack(&oss, NULL);
-    }
-
-    /*
-     * Restore the old SIGUSR2 signal handler and mask
-     */
-    sigaction(SIGUSR2, &osa, NULL);
-    pthread_sigmask(SIG_SETMASK, &osigs, NULL);
-
-    /*
-     * Now enter the trampoline again, but this time not as a signal
-     * handler. Instead we jump into it directly. The functionally
-     * redundant ping-pong pointer arithmetic is necessary to avoid
-     * type-conversion warnings related to the `volatile' qualifier and
-     * the fact that `jmp_buf' usually is an array type.
-     */
-    if (!sigsetjmp(old_env, 0)) {
-        siglongjmp(coTS->tr_reenter, 1);
-    }
-
-    /*
-     * Ok, we returned again, so now we're finished
-     */
-
-    return &co->base;
-}
-
-void qemu_coroutine_delete(Coroutine *co_)
-{
-    CoroutineUContext *co = DO_UPCAST(CoroutineUContext, base, co_);
-
-    g_free(co->stack);
-    g_free(co);
-}
-
-CoroutineAction qemu_coroutine_switch(Coroutine *from_, Coroutine *to_,
-                                      CoroutineAction action)
-{
-    CoroutineUContext *from = DO_UPCAST(CoroutineUContext, base, from_);
-    CoroutineUContext *to = DO_UPCAST(CoroutineUContext, base, to_);
-    CoroutineThreadState *s = coroutine_get_thread_state();
-    int ret;
-
-    s->current = to_;
-
-    ret = sigsetjmp(from->env, 0);
-    if (ret == 0) {
-        siglongjmp(to->env, action);
-    }
-    return ret;
-}
-
-Coroutine *qemu_coroutine_self(void)
-{
-    CoroutineThreadState *s = coroutine_get_thread_state();
-
-    return s->current;
-}
-
-bool qemu_in_coroutine(void)
-{
-    CoroutineThreadState *s = pthread_getspecific(thread_state_key);
-
-    return s && s->current->caller;
-}
-