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d2623129a7
The only way object_property_add() can fail is when a property with the same name already exists. Since our property names are all hardcoded, failure is a programming error, and the appropriate way to handle it is passing &error_abort. Same for its variants, except for object_property_add_child(), which additionally fails when the child already has a parent. Parentage is also under program control, so this is a programming error, too. We have a bit over 500 callers. Almost half of them pass &error_abort, slightly fewer ignore errors, one test case handles errors, and the remaining few callers pass them to their own callers. The previous few commits demonstrated once again that ignoring programming errors is a bad idea. Of the few ones that pass on errors, several violate the Error API. The Error ** argument must be NULL, &error_abort, &error_fatal, or a pointer to a variable containing NULL. Passing an argument of the latter kind twice without clearing it in between is wrong: if the first call sets an error, it no longer points to NULL for the second call. ich9_pm_add_properties(), sparc32_ledma_realize(), sparc32_dma_realize(), xilinx_axidma_realize(), xilinx_enet_realize() are wrong that way. When the one appropriate choice of argument is &error_abort, letting users pick the argument is a bad idea. Drop parameter @errp and assert the preconditions instead. There's one exception to "duplicate property name is a programming error": the way object_property_add() implements the magic (and undocumented) "automatic arrayification". Don't drop @errp there. Instead, rename object_property_add() to object_property_try_add(), and add the obvious wrapper object_property_add(). Signed-off-by: Markus Armbruster <armbru@redhat.com> Reviewed-by: Eric Blake <eblake@redhat.com> Reviewed-by: Paolo Bonzini <pbonzini@redhat.com> Message-Id: <20200505152926.18877-15-armbru@redhat.com> [Two semantic rebase conflicts resolved]
387 lines
11 KiB
C
387 lines
11 KiB
C
/*
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* Event loop thread
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*
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* Copyright Red Hat Inc., 2013
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*
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* Authors:
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* Stefan Hajnoczi <stefanha@redhat.com>
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*
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* This work is licensed under the terms of the GNU GPL, version 2 or later.
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* See the COPYING file in the top-level directory.
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*
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*/
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#include "qemu/osdep.h"
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#include "qom/object.h"
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#include "qom/object_interfaces.h"
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#include "qemu/module.h"
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#include "block/aio.h"
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#include "block/block.h"
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#include "sysemu/iothread.h"
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#include "qapi/error.h"
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#include "qapi/qapi-commands-misc.h"
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#include "qemu/error-report.h"
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#include "qemu/rcu.h"
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#include "qemu/main-loop.h"
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typedef ObjectClass IOThreadClass;
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#define IOTHREAD_GET_CLASS(obj) \
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OBJECT_GET_CLASS(IOThreadClass, obj, TYPE_IOTHREAD)
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#define IOTHREAD_CLASS(klass) \
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OBJECT_CLASS_CHECK(IOThreadClass, klass, TYPE_IOTHREAD)
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#ifdef CONFIG_POSIX
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/* Benchmark results from 2016 on NVMe SSD drives show max polling times around
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* 16-32 microseconds yield IOPS improvements for both iodepth=1 and iodepth=32
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* workloads.
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*/
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#define IOTHREAD_POLL_MAX_NS_DEFAULT 32768ULL
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#else
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#define IOTHREAD_POLL_MAX_NS_DEFAULT 0ULL
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#endif
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static __thread IOThread *my_iothread;
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AioContext *qemu_get_current_aio_context(void)
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{
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return my_iothread ? my_iothread->ctx : qemu_get_aio_context();
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}
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static void *iothread_run(void *opaque)
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{
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IOThread *iothread = opaque;
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rcu_register_thread();
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/*
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* g_main_context_push_thread_default() must be called before anything
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* in this new thread uses glib.
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*/
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g_main_context_push_thread_default(iothread->worker_context);
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my_iothread = iothread;
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iothread->thread_id = qemu_get_thread_id();
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qemu_sem_post(&iothread->init_done_sem);
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while (iothread->running) {
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/*
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* Note: from functional-wise the g_main_loop_run() below can
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* already cover the aio_poll() events, but we can't run the
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* main loop unconditionally because explicit aio_poll() here
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* is faster than g_main_loop_run() when we do not need the
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* gcontext at all (e.g., pure block layer iothreads). In
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* other words, when we want to run the gcontext with the
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* iothread we need to pay some performance for functionality.
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*/
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aio_poll(iothread->ctx, true);
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/*
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* We must check the running state again in case it was
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* changed in previous aio_poll()
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*/
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if (iothread->running && atomic_read(&iothread->run_gcontext)) {
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g_main_loop_run(iothread->main_loop);
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}
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}
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g_main_context_pop_thread_default(iothread->worker_context);
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rcu_unregister_thread();
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return NULL;
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}
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/* Runs in iothread_run() thread */
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static void iothread_stop_bh(void *opaque)
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{
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IOThread *iothread = opaque;
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iothread->running = false; /* stop iothread_run() */
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if (iothread->main_loop) {
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g_main_loop_quit(iothread->main_loop);
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}
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}
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void iothread_stop(IOThread *iothread)
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{
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if (!iothread->ctx || iothread->stopping) {
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return;
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}
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iothread->stopping = true;
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aio_bh_schedule_oneshot(iothread->ctx, iothread_stop_bh, iothread);
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qemu_thread_join(&iothread->thread);
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}
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static void iothread_instance_init(Object *obj)
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{
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IOThread *iothread = IOTHREAD(obj);
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iothread->poll_max_ns = IOTHREAD_POLL_MAX_NS_DEFAULT;
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iothread->thread_id = -1;
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qemu_sem_init(&iothread->init_done_sem, 0);
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/* By default, we don't run gcontext */
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atomic_set(&iothread->run_gcontext, 0);
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}
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static void iothread_instance_finalize(Object *obj)
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{
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IOThread *iothread = IOTHREAD(obj);
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iothread_stop(iothread);
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/*
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* Before glib2 2.33.10, there is a glib2 bug that GSource context
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* pointer may not be cleared even if the context has already been
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* destroyed (while it should). Here let's free the AIO context
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* earlier to bypass that glib bug.
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*
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* We can remove this comment after the minimum supported glib2
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* version boosts to 2.33.10. Before that, let's free the
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* GSources first before destroying any GMainContext.
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*/
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if (iothread->ctx) {
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aio_context_unref(iothread->ctx);
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iothread->ctx = NULL;
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}
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if (iothread->worker_context) {
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g_main_context_unref(iothread->worker_context);
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iothread->worker_context = NULL;
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g_main_loop_unref(iothread->main_loop);
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iothread->main_loop = NULL;
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}
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qemu_sem_destroy(&iothread->init_done_sem);
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}
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static void iothread_init_gcontext(IOThread *iothread)
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{
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GSource *source;
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iothread->worker_context = g_main_context_new();
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source = aio_get_g_source(iothread_get_aio_context(iothread));
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g_source_attach(source, iothread->worker_context);
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g_source_unref(source);
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iothread->main_loop = g_main_loop_new(iothread->worker_context, TRUE);
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}
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static void iothread_complete(UserCreatable *obj, Error **errp)
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{
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Error *local_error = NULL;
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IOThread *iothread = IOTHREAD(obj);
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char *name, *thread_name;
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iothread->stopping = false;
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iothread->running = true;
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iothread->ctx = aio_context_new(&local_error);
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if (!iothread->ctx) {
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error_propagate(errp, local_error);
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return;
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}
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/*
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* Init one GMainContext for the iothread unconditionally, even if
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* it's not used
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*/
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iothread_init_gcontext(iothread);
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aio_context_set_poll_params(iothread->ctx,
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iothread->poll_max_ns,
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iothread->poll_grow,
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iothread->poll_shrink,
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&local_error);
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if (local_error) {
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error_propagate(errp, local_error);
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aio_context_unref(iothread->ctx);
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iothread->ctx = NULL;
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return;
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}
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/* This assumes we are called from a thread with useful CPU affinity for us
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* to inherit.
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*/
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name = object_get_canonical_path_component(OBJECT(obj));
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thread_name = g_strdup_printf("IO %s", name);
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qemu_thread_create(&iothread->thread, thread_name, iothread_run,
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iothread, QEMU_THREAD_JOINABLE);
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g_free(thread_name);
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g_free(name);
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/* Wait for initialization to complete */
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while (iothread->thread_id == -1) {
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qemu_sem_wait(&iothread->init_done_sem);
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}
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}
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typedef struct {
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const char *name;
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ptrdiff_t offset; /* field's byte offset in IOThread struct */
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} PollParamInfo;
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static PollParamInfo poll_max_ns_info = {
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"poll-max-ns", offsetof(IOThread, poll_max_ns),
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};
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static PollParamInfo poll_grow_info = {
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"poll-grow", offsetof(IOThread, poll_grow),
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};
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static PollParamInfo poll_shrink_info = {
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"poll-shrink", offsetof(IOThread, poll_shrink),
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};
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static void iothread_get_poll_param(Object *obj, Visitor *v,
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const char *name, void *opaque, Error **errp)
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{
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IOThread *iothread = IOTHREAD(obj);
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PollParamInfo *info = opaque;
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int64_t *field = (void *)iothread + info->offset;
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visit_type_int64(v, name, field, errp);
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}
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static void iothread_set_poll_param(Object *obj, Visitor *v,
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const char *name, void *opaque, Error **errp)
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{
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IOThread *iothread = IOTHREAD(obj);
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PollParamInfo *info = opaque;
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int64_t *field = (void *)iothread + info->offset;
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Error *local_err = NULL;
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int64_t value;
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visit_type_int64(v, name, &value, &local_err);
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if (local_err) {
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goto out;
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}
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if (value < 0) {
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error_setg(&local_err, "%s value must be in range [0, %"PRId64"]",
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info->name, INT64_MAX);
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goto out;
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}
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*field = value;
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if (iothread->ctx) {
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aio_context_set_poll_params(iothread->ctx,
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iothread->poll_max_ns,
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iothread->poll_grow,
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iothread->poll_shrink,
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&local_err);
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}
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out:
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error_propagate(errp, local_err);
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}
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static void iothread_class_init(ObjectClass *klass, void *class_data)
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{
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UserCreatableClass *ucc = USER_CREATABLE_CLASS(klass);
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ucc->complete = iothread_complete;
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object_class_property_add(klass, "poll-max-ns", "int",
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iothread_get_poll_param,
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iothread_set_poll_param,
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NULL, &poll_max_ns_info);
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object_class_property_add(klass, "poll-grow", "int",
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iothread_get_poll_param,
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iothread_set_poll_param,
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NULL, &poll_grow_info);
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object_class_property_add(klass, "poll-shrink", "int",
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iothread_get_poll_param,
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iothread_set_poll_param,
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NULL, &poll_shrink_info);
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}
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static const TypeInfo iothread_info = {
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.name = TYPE_IOTHREAD,
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.parent = TYPE_OBJECT,
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.class_init = iothread_class_init,
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.instance_size = sizeof(IOThread),
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.instance_init = iothread_instance_init,
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.instance_finalize = iothread_instance_finalize,
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.interfaces = (InterfaceInfo[]) {
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{TYPE_USER_CREATABLE},
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{}
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},
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};
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static void iothread_register_types(void)
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{
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type_register_static(&iothread_info);
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}
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type_init(iothread_register_types)
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char *iothread_get_id(IOThread *iothread)
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{
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return object_get_canonical_path_component(OBJECT(iothread));
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}
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AioContext *iothread_get_aio_context(IOThread *iothread)
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{
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return iothread->ctx;
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}
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static int query_one_iothread(Object *object, void *opaque)
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{
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IOThreadInfoList ***prev = opaque;
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IOThreadInfoList *elem;
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IOThreadInfo *info;
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IOThread *iothread;
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iothread = (IOThread *)object_dynamic_cast(object, TYPE_IOTHREAD);
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if (!iothread) {
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return 0;
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}
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info = g_new0(IOThreadInfo, 1);
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info->id = iothread_get_id(iothread);
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info->thread_id = iothread->thread_id;
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info->poll_max_ns = iothread->poll_max_ns;
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info->poll_grow = iothread->poll_grow;
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info->poll_shrink = iothread->poll_shrink;
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elem = g_new0(IOThreadInfoList, 1);
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elem->value = info;
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elem->next = NULL;
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**prev = elem;
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*prev = &elem->next;
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return 0;
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}
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IOThreadInfoList *qmp_query_iothreads(Error **errp)
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{
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IOThreadInfoList *head = NULL;
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IOThreadInfoList **prev = &head;
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Object *container = object_get_objects_root();
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object_child_foreach(container, query_one_iothread, &prev);
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return head;
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}
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GMainContext *iothread_get_g_main_context(IOThread *iothread)
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{
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atomic_set(&iothread->run_gcontext, 1);
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aio_notify(iothread->ctx);
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return iothread->worker_context;
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}
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IOThread *iothread_create(const char *id, Error **errp)
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{
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Object *obj;
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obj = object_new_with_props(TYPE_IOTHREAD,
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object_get_internal_root(),
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id, errp, NULL);
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return IOTHREAD(obj);
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}
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void iothread_destroy(IOThread *iothread)
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{
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object_unparent(OBJECT(iothread));
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}
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/* Lookup IOThread by its id. Only finds user-created objects, not internal
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* iothread_create() objects. */
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IOThread *iothread_by_id(const char *id)
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{
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return IOTHREAD(object_resolve_path_type(id, TYPE_IOTHREAD, NULL));
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}
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