| /* |
| * QEMU System Emulator |
| * |
| * Copyright (c) 2003-2008 Fabrice Bellard |
| * |
| * Permission is hereby granted, free of charge, to any person obtaining a copy |
| * of this software and associated documentation files (the "Software"), to deal |
| * in the Software without restriction, including without limitation the rights |
| * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell |
| * copies of the Software, and to permit persons to whom the Software is |
| * furnished to do so, subject to the following conditions: |
| * |
| * The above copyright notice and this permission notice shall be included in |
| * all copies or substantial portions of the Software. |
| * |
| * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR |
| * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, |
| * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL |
| * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER |
| * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, |
| * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN |
| * THE SOFTWARE. |
| */ |
| |
| #include "qemu-common.h" |
| #include "block/aio.h" |
| #include "block/thread-pool.h" |
| #include "qemu/main-loop.h" |
| #include "qemu/atomic.h" |
| |
| /***********************************************************/ |
| /* bottom halves (can be seen as timers which expire ASAP) */ |
| |
| struct QEMUBH { |
| AioContext *ctx; |
| QEMUBHFunc *cb; |
| void *opaque; |
| QEMUBH *next; |
| bool scheduled; |
| bool idle; |
| bool deleted; |
| }; |
| |
| QEMUBH *aio_bh_new(AioContext *ctx, QEMUBHFunc *cb, void *opaque) |
| { |
| QEMUBH *bh; |
| bh = g_malloc0(sizeof(QEMUBH)); |
| bh->ctx = ctx; |
| bh->cb = cb; |
| bh->opaque = opaque; |
| qemu_mutex_lock(&ctx->bh_lock); |
| bh->next = ctx->first_bh; |
| /* Make sure that the members are ready before putting bh into list */ |
| smp_wmb(); |
| ctx->first_bh = bh; |
| qemu_mutex_unlock(&ctx->bh_lock); |
| return bh; |
| } |
| |
| /* Multiple occurrences of aio_bh_poll cannot be called concurrently */ |
| int aio_bh_poll(AioContext *ctx) |
| { |
| QEMUBH *bh, **bhp, *next; |
| int ret; |
| |
| ctx->walking_bh++; |
| |
| ret = 0; |
| for (bh = ctx->first_bh; bh; bh = next) { |
| /* Make sure that fetching bh happens before accessing its members */ |
| smp_read_barrier_depends(); |
| next = bh->next; |
| if (!bh->deleted && bh->scheduled) { |
| bh->scheduled = 0; |
| /* Paired with write barrier in bh schedule to ensure reading for |
| * idle & callbacks coming after bh's scheduling. |
| */ |
| smp_rmb(); |
| if (!bh->idle) |
| ret = 1; |
| bh->idle = 0; |
| bh->cb(bh->opaque); |
| } |
| } |
| |
| ctx->walking_bh--; |
| |
| /* remove deleted bhs */ |
| if (!ctx->walking_bh) { |
| qemu_mutex_lock(&ctx->bh_lock); |
| bhp = &ctx->first_bh; |
| while (*bhp) { |
| bh = *bhp; |
| if (bh->deleted) { |
| *bhp = bh->next; |
| g_free(bh); |
| } else { |
| bhp = &bh->next; |
| } |
| } |
| qemu_mutex_unlock(&ctx->bh_lock); |
| } |
| |
| return ret; |
| } |
| |
| void qemu_bh_schedule_idle(QEMUBH *bh) |
| { |
| if (bh->scheduled) |
| return; |
| bh->idle = 1; |
| /* Make sure that idle & any writes needed by the callback are done |
| * before the locations are read in the aio_bh_poll. |
| */ |
| smp_wmb(); |
| bh->scheduled = 1; |
| } |
| |
| void qemu_bh_schedule(QEMUBH *bh) |
| { |
| AioContext *ctx; |
| |
| if (bh->scheduled) |
| return; |
| ctx = bh->ctx; |
| bh->idle = 0; |
| /* Make sure that: |
| * 1. idle & any writes needed by the callback are done before the |
| * locations are read in the aio_bh_poll. |
| * 2. ctx is loaded before scheduled is set and the callback has a chance |
| * to execute. |
| */ |
| smp_mb(); |
| bh->scheduled = 1; |
| aio_notify(ctx); |
| } |
| |
| |
| /* This func is async. |
| */ |
| void qemu_bh_cancel(QEMUBH *bh) |
| { |
| bh->scheduled = 0; |
| } |
| |
| /* This func is async.The bottom half will do the delete action at the finial |
| * end. |
| */ |
| void qemu_bh_delete(QEMUBH *bh) |
| { |
| bh->scheduled = 0; |
| bh->deleted = 1; |
| } |
| |
| int64_t |
| aio_compute_timeout(AioContext *ctx) |
| { |
| int64_t deadline; |
| int timeout = -1; |
| QEMUBH *bh; |
| |
| for (bh = ctx->first_bh; bh; bh = bh->next) { |
| if (!bh->deleted && bh->scheduled) { |
| if (bh->idle) { |
| /* idle bottom halves will be polled at least |
| * every 10ms */ |
| timeout = 10000000; |
| } else { |
| /* non-idle bottom halves will be executed |
| * immediately */ |
| return 0; |
| } |
| } |
| } |
| |
| deadline = timerlistgroup_deadline_ns(&ctx->tlg); |
| if (deadline == 0) { |
| return 0; |
| } else { |
| return qemu_soonest_timeout(timeout, deadline); |
| } |
| } |
| |
| static gboolean |
| aio_ctx_prepare(GSource *source, gint *timeout) |
| { |
| AioContext *ctx = (AioContext *) source; |
| |
| /* We assume there is no timeout already supplied */ |
| *timeout = qemu_timeout_ns_to_ms(aio_compute_timeout(ctx)); |
| |
| if (aio_prepare(ctx)) { |
| *timeout = 0; |
| } |
| |
| return *timeout == 0; |
| } |
| |
| static gboolean |
| aio_ctx_check(GSource *source) |
| { |
| AioContext *ctx = (AioContext *) source; |
| QEMUBH *bh; |
| |
| for (bh = ctx->first_bh; bh; bh = bh->next) { |
| if (!bh->deleted && bh->scheduled) { |
| return true; |
| } |
| } |
| return aio_pending(ctx) || (timerlistgroup_deadline_ns(&ctx->tlg) == 0); |
| } |
| |
| static gboolean |
| aio_ctx_dispatch(GSource *source, |
| GSourceFunc callback, |
| gpointer user_data) |
| { |
| AioContext *ctx = (AioContext *) source; |
| |
| assert(callback == NULL); |
| aio_dispatch(ctx); |
| return true; |
| } |
| |
| static void |
| aio_ctx_finalize(GSource *source) |
| { |
| AioContext *ctx = (AioContext *) source; |
| |
| thread_pool_free(ctx->thread_pool); |
| aio_set_event_notifier(ctx, &ctx->notifier, NULL); |
| event_notifier_cleanup(&ctx->notifier); |
| rfifolock_destroy(&ctx->lock); |
| qemu_mutex_destroy(&ctx->bh_lock); |
| g_array_free(ctx->pollfds, TRUE); |
| timerlistgroup_deinit(&ctx->tlg); |
| } |
| |
| static GSourceFuncs aio_source_funcs = { |
| aio_ctx_prepare, |
| aio_ctx_check, |
| aio_ctx_dispatch, |
| aio_ctx_finalize |
| }; |
| |
| GSource *aio_get_g_source(AioContext *ctx) |
| { |
| g_source_ref(&ctx->source); |
| return &ctx->source; |
| } |
| |
| ThreadPool *aio_get_thread_pool(AioContext *ctx) |
| { |
| if (!ctx->thread_pool) { |
| ctx->thread_pool = thread_pool_new(ctx); |
| } |
| return ctx->thread_pool; |
| } |
| |
| void aio_set_dispatching(AioContext *ctx, bool dispatching) |
| { |
| ctx->dispatching = dispatching; |
| if (!dispatching) { |
| /* Write ctx->dispatching before reading e.g. bh->scheduled. |
| * Optimization: this is only needed when we're entering the "unsafe" |
| * phase where other threads must call event_notifier_set. |
| */ |
| smp_mb(); |
| } |
| } |
| |
| void aio_notify(AioContext *ctx) |
| { |
| /* Write e.g. bh->scheduled before reading ctx->dispatching. */ |
| smp_mb(); |
| if (!ctx->dispatching) { |
| event_notifier_set(&ctx->notifier); |
| } |
| } |
| |
| static void aio_timerlist_notify(void *opaque) |
| { |
| aio_notify(opaque); |
| } |
| |
| static void aio_rfifolock_cb(void *opaque) |
| { |
| /* Kick owner thread in case they are blocked in aio_poll() */ |
| aio_notify(opaque); |
| } |
| |
| AioContext *aio_context_new(Error **errp) |
| { |
| int ret; |
| AioContext *ctx; |
| ctx = (AioContext *) g_source_new(&aio_source_funcs, sizeof(AioContext)); |
| ret = event_notifier_init(&ctx->notifier, false); |
| if (ret < 0) { |
| g_source_destroy(&ctx->source); |
| error_setg_errno(errp, -ret, "Failed to initialize event notifier"); |
| return NULL; |
| } |
| aio_set_event_notifier(ctx, &ctx->notifier, |
| (EventNotifierHandler *) |
| event_notifier_test_and_clear); |
| ctx->pollfds = g_array_new(FALSE, FALSE, sizeof(GPollFD)); |
| ctx->thread_pool = NULL; |
| qemu_mutex_init(&ctx->bh_lock); |
| rfifolock_init(&ctx->lock, aio_rfifolock_cb, ctx); |
| timerlistgroup_init(&ctx->tlg, aio_timerlist_notify, ctx); |
| |
| return ctx; |
| } |
| |
| void aio_context_ref(AioContext *ctx) |
| { |
| g_source_ref(&ctx->source); |
| } |
| |
| void aio_context_unref(AioContext *ctx) |
| { |
| g_source_unref(&ctx->source); |
| } |
| |
| void aio_context_acquire(AioContext *ctx) |
| { |
| rfifolock_lock(&ctx->lock); |
| } |
| |
| void aio_context_release(AioContext *ctx) |
| { |
| rfifolock_unlock(&ctx->lock); |
| } |