697 lines
18 KiB
C
697 lines
18 KiB
C
/*
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* Data plane event loop
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*
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* Copyright (c) 2003-2008 Fabrice Bellard
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* Copyright (c) 2009-2017 QEMU contributors
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*
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* Permission is hereby granted, free of charge, to any person obtaining a copy
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* of this software and associated documentation files (the "Software"), to deal
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* in the Software without restriction, including without limitation the rights
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* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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* copies of the Software, and to permit persons to whom the Software is
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* furnished to do so, subject to the following conditions:
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*
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* The above copyright notice and this permission notice shall be included in
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* all copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
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* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
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* THE SOFTWARE.
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*/
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#include "qemu/osdep.h"
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#include "qapi/error.h"
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#include "block/aio.h"
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#include "block/thread-pool.h"
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#include "qemu/main-loop.h"
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#include "qemu/atomic.h"
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#include "qemu/rcu_queue.h"
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#include "block/raw-aio.h"
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#include "qemu/coroutine_int.h"
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#include "trace.h"
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/***********************************************************/
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/* bottom halves (can be seen as timers which expire ASAP) */
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/* QEMUBH::flags values */
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enum {
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/* Already enqueued and waiting for aio_bh_poll() */
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BH_PENDING = (1 << 0),
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/* Invoke the callback */
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BH_SCHEDULED = (1 << 1),
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/* Delete without invoking callback */
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BH_DELETED = (1 << 2),
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/* Delete after invoking callback */
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BH_ONESHOT = (1 << 3),
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/* Schedule periodically when the event loop is idle */
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BH_IDLE = (1 << 4),
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};
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struct QEMUBH {
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AioContext *ctx;
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const char *name;
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QEMUBHFunc *cb;
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void *opaque;
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QSLIST_ENTRY(QEMUBH) next;
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unsigned flags;
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};
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/* Called concurrently from any thread */
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static void aio_bh_enqueue(QEMUBH *bh, unsigned new_flags)
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{
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AioContext *ctx = bh->ctx;
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unsigned old_flags;
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/*
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* The memory barrier implicit in qatomic_fetch_or makes sure that:
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* 1. idle & any writes needed by the callback are done before the
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* locations are read in the aio_bh_poll.
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* 2. ctx is loaded before the callback has a chance to execute and bh
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* could be freed.
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*/
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old_flags = qatomic_fetch_or(&bh->flags, BH_PENDING | new_flags);
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if (!(old_flags & BH_PENDING)) {
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QSLIST_INSERT_HEAD_ATOMIC(&ctx->bh_list, bh, next);
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}
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aio_notify(ctx);
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}
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/* Only called from aio_bh_poll() and aio_ctx_finalize() */
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static QEMUBH *aio_bh_dequeue(BHList *head, unsigned *flags)
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{
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QEMUBH *bh = QSLIST_FIRST_RCU(head);
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if (!bh) {
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return NULL;
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}
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QSLIST_REMOVE_HEAD(head, next);
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/*
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* The qatomic_and is paired with aio_bh_enqueue(). The implicit memory
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* barrier ensures that the callback sees all writes done by the scheduling
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* thread. It also ensures that the scheduling thread sees the cleared
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* flag before bh->cb has run, and thus will call aio_notify again if
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* necessary.
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*/
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*flags = qatomic_fetch_and(&bh->flags,
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~(BH_PENDING | BH_SCHEDULED | BH_IDLE));
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return bh;
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}
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void aio_bh_schedule_oneshot_full(AioContext *ctx, QEMUBHFunc *cb,
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void *opaque, const char *name)
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{
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QEMUBH *bh;
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bh = g_new(QEMUBH, 1);
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*bh = (QEMUBH){
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.ctx = ctx,
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.cb = cb,
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.opaque = opaque,
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.name = name,
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};
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aio_bh_enqueue(bh, BH_SCHEDULED | BH_ONESHOT);
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}
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QEMUBH *aio_bh_new_full(AioContext *ctx, QEMUBHFunc *cb, void *opaque,
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const char *name)
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{
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QEMUBH *bh;
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bh = g_new(QEMUBH, 1);
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*bh = (QEMUBH){
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.ctx = ctx,
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.cb = cb,
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.opaque = opaque,
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.name = name,
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};
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return bh;
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}
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void aio_bh_call(QEMUBH *bh)
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{
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bh->cb(bh->opaque);
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}
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/* Multiple occurrences of aio_bh_poll cannot be called concurrently. */
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int aio_bh_poll(AioContext *ctx)
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{
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BHListSlice slice;
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BHListSlice *s;
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int ret = 0;
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QSLIST_MOVE_ATOMIC(&slice.bh_list, &ctx->bh_list);
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QSIMPLEQ_INSERT_TAIL(&ctx->bh_slice_list, &slice, next);
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while ((s = QSIMPLEQ_FIRST(&ctx->bh_slice_list))) {
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QEMUBH *bh;
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unsigned flags;
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bh = aio_bh_dequeue(&s->bh_list, &flags);
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if (!bh) {
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QSIMPLEQ_REMOVE_HEAD(&ctx->bh_slice_list, next);
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continue;
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}
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if ((flags & (BH_SCHEDULED | BH_DELETED)) == BH_SCHEDULED) {
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/* Idle BHs don't count as progress */
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if (!(flags & BH_IDLE)) {
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ret = 1;
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}
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aio_bh_call(bh);
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}
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if (flags & (BH_DELETED | BH_ONESHOT)) {
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g_free(bh);
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}
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}
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return ret;
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}
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void qemu_bh_schedule_idle(QEMUBH *bh)
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{
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aio_bh_enqueue(bh, BH_SCHEDULED | BH_IDLE);
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}
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void qemu_bh_schedule(QEMUBH *bh)
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{
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aio_bh_enqueue(bh, BH_SCHEDULED);
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}
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/* This func is async.
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*/
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void qemu_bh_cancel(QEMUBH *bh)
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{
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qatomic_and(&bh->flags, ~BH_SCHEDULED);
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}
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/* This func is async.The bottom half will do the delete action at the finial
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* end.
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*/
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void qemu_bh_delete(QEMUBH *bh)
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{
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aio_bh_enqueue(bh, BH_DELETED);
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}
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static int64_t aio_compute_bh_timeout(BHList *head, int timeout)
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{
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QEMUBH *bh;
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QSLIST_FOREACH_RCU(bh, head, next) {
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if ((bh->flags & (BH_SCHEDULED | BH_DELETED)) == BH_SCHEDULED) {
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if (bh->flags & BH_IDLE) {
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/* idle bottom halves will be polled at least
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* every 10ms */
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timeout = 10000000;
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} else {
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/* non-idle bottom halves will be executed
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* immediately */
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return 0;
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}
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}
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}
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return timeout;
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}
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int64_t
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aio_compute_timeout(AioContext *ctx)
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{
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BHListSlice *s;
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int64_t deadline;
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int timeout = -1;
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timeout = aio_compute_bh_timeout(&ctx->bh_list, timeout);
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if (timeout == 0) {
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return 0;
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}
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QSIMPLEQ_FOREACH(s, &ctx->bh_slice_list, next) {
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timeout = aio_compute_bh_timeout(&s->bh_list, timeout);
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if (timeout == 0) {
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return 0;
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}
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}
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deadline = timerlistgroup_deadline_ns(&ctx->tlg);
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if (deadline == 0) {
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return 0;
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} else {
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return qemu_soonest_timeout(timeout, deadline);
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}
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}
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static gboolean
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aio_ctx_prepare(GSource *source, gint *timeout)
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{
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AioContext *ctx = (AioContext *) source;
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qatomic_set(&ctx->notify_me, qatomic_read(&ctx->notify_me) | 1);
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/*
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* Write ctx->notify_me before computing the timeout
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* (reading bottom half flags, etc.). Pairs with
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* smp_mb in aio_notify().
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*/
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smp_mb();
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/* We assume there is no timeout already supplied */
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*timeout = qemu_timeout_ns_to_ms(aio_compute_timeout(ctx));
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if (aio_prepare(ctx)) {
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*timeout = 0;
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}
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return *timeout == 0;
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}
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static gboolean
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aio_ctx_check(GSource *source)
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{
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AioContext *ctx = (AioContext *) source;
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QEMUBH *bh;
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BHListSlice *s;
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/* Finish computing the timeout before clearing the flag. */
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qatomic_store_release(&ctx->notify_me, qatomic_read(&ctx->notify_me) & ~1);
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aio_notify_accept(ctx);
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QSLIST_FOREACH_RCU(bh, &ctx->bh_list, next) {
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if ((bh->flags & (BH_SCHEDULED | BH_DELETED)) == BH_SCHEDULED) {
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return true;
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}
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}
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QSIMPLEQ_FOREACH(s, &ctx->bh_slice_list, next) {
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QSLIST_FOREACH_RCU(bh, &s->bh_list, next) {
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if ((bh->flags & (BH_SCHEDULED | BH_DELETED)) == BH_SCHEDULED) {
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return true;
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}
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}
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}
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return aio_pending(ctx) || (timerlistgroup_deadline_ns(&ctx->tlg) == 0);
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}
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static gboolean
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aio_ctx_dispatch(GSource *source,
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GSourceFunc callback,
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gpointer user_data)
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{
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AioContext *ctx = (AioContext *) source;
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assert(callback == NULL);
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aio_dispatch(ctx);
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return true;
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}
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static void
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aio_ctx_finalize(GSource *source)
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{
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AioContext *ctx = (AioContext *) source;
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QEMUBH *bh;
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unsigned flags;
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thread_pool_free(ctx->thread_pool);
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#ifdef CONFIG_LINUX_AIO
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if (ctx->linux_aio) {
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laio_detach_aio_context(ctx->linux_aio, ctx);
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laio_cleanup(ctx->linux_aio);
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ctx->linux_aio = NULL;
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}
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#endif
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#ifdef CONFIG_LINUX_IO_URING
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if (ctx->linux_io_uring) {
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luring_detach_aio_context(ctx->linux_io_uring, ctx);
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luring_cleanup(ctx->linux_io_uring);
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ctx->linux_io_uring = NULL;
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}
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#endif
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assert(QSLIST_EMPTY(&ctx->scheduled_coroutines));
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qemu_bh_delete(ctx->co_schedule_bh);
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/* There must be no aio_bh_poll() calls going on */
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assert(QSIMPLEQ_EMPTY(&ctx->bh_slice_list));
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while ((bh = aio_bh_dequeue(&ctx->bh_list, &flags))) {
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/*
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* qemu_bh_delete() must have been called on BHs in this AioContext. In
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* many cases memory leaks, hangs, or inconsistent state occur when a
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* BH is leaked because something still expects it to run.
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*
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* If you hit this, fix the lifecycle of the BH so that
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* qemu_bh_delete() and any associated cleanup is called before the
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* AioContext is finalized.
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*/
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if (unlikely(!(flags & BH_DELETED))) {
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fprintf(stderr, "%s: BH '%s' leaked, aborting...\n",
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__func__, bh->name);
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abort();
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}
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g_free(bh);
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}
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aio_set_event_notifier(ctx, &ctx->notifier, false, NULL, NULL, NULL);
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event_notifier_cleanup(&ctx->notifier);
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qemu_rec_mutex_destroy(&ctx->lock);
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qemu_lockcnt_destroy(&ctx->list_lock);
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timerlistgroup_deinit(&ctx->tlg);
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aio_context_destroy(ctx);
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}
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static GSourceFuncs aio_source_funcs = {
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aio_ctx_prepare,
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aio_ctx_check,
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aio_ctx_dispatch,
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aio_ctx_finalize
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};
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GSource *aio_get_g_source(AioContext *ctx)
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{
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aio_context_use_g_source(ctx);
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g_source_ref(&ctx->source);
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return &ctx->source;
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}
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ThreadPool *aio_get_thread_pool(AioContext *ctx)
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{
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if (!ctx->thread_pool) {
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ctx->thread_pool = thread_pool_new(ctx);
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}
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return ctx->thread_pool;
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}
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#ifdef CONFIG_LINUX_AIO
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LinuxAioState *aio_setup_linux_aio(AioContext *ctx, Error **errp)
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{
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if (!ctx->linux_aio) {
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ctx->linux_aio = laio_init(errp);
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if (ctx->linux_aio) {
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laio_attach_aio_context(ctx->linux_aio, ctx);
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}
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}
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return ctx->linux_aio;
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}
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LinuxAioState *aio_get_linux_aio(AioContext *ctx)
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{
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assert(ctx->linux_aio);
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return ctx->linux_aio;
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}
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#endif
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#ifdef CONFIG_LINUX_IO_URING
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LuringState *aio_setup_linux_io_uring(AioContext *ctx, Error **errp)
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{
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if (ctx->linux_io_uring) {
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return ctx->linux_io_uring;
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}
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ctx->linux_io_uring = luring_init(errp);
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if (!ctx->linux_io_uring) {
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return NULL;
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}
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luring_attach_aio_context(ctx->linux_io_uring, ctx);
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return ctx->linux_io_uring;
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}
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LuringState *aio_get_linux_io_uring(AioContext *ctx)
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{
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assert(ctx->linux_io_uring);
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return ctx->linux_io_uring;
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}
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#endif
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void aio_notify(AioContext *ctx)
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{
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/*
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* Write e.g. bh->flags before writing ctx->notified. Pairs with smp_mb in
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* aio_notify_accept.
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*/
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smp_wmb();
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qatomic_set(&ctx->notified, true);
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/*
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* Write ctx->notified before reading ctx->notify_me. Pairs
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* with smp_mb in aio_ctx_prepare or aio_poll.
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*/
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smp_mb();
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if (qatomic_read(&ctx->notify_me)) {
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event_notifier_set(&ctx->notifier);
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}
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}
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void aio_notify_accept(AioContext *ctx)
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{
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qatomic_set(&ctx->notified, false);
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/*
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* Write ctx->notified before reading e.g. bh->flags. Pairs with smp_wmb
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* in aio_notify.
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*/
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smp_mb();
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}
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static void aio_timerlist_notify(void *opaque, QEMUClockType type)
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{
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aio_notify(opaque);
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}
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static void aio_context_notifier_cb(EventNotifier *e)
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{
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AioContext *ctx = container_of(e, AioContext, notifier);
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event_notifier_test_and_clear(&ctx->notifier);
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}
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/* Returns true if aio_notify() was called (e.g. a BH was scheduled) */
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static bool aio_context_notifier_poll(void *opaque)
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{
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EventNotifier *e = opaque;
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AioContext *ctx = container_of(e, AioContext, notifier);
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return qatomic_read(&ctx->notified);
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}
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static void aio_context_notifier_poll_ready(EventNotifier *e)
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{
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/* Do nothing, we just wanted to kick the event loop */
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}
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static void co_schedule_bh_cb(void *opaque)
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{
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AioContext *ctx = opaque;
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QSLIST_HEAD(, Coroutine) straight, reversed;
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QSLIST_MOVE_ATOMIC(&reversed, &ctx->scheduled_coroutines);
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QSLIST_INIT(&straight);
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while (!QSLIST_EMPTY(&reversed)) {
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Coroutine *co = QSLIST_FIRST(&reversed);
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QSLIST_REMOVE_HEAD(&reversed, co_scheduled_next);
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QSLIST_INSERT_HEAD(&straight, co, co_scheduled_next);
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}
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while (!QSLIST_EMPTY(&straight)) {
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Coroutine *co = QSLIST_FIRST(&straight);
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QSLIST_REMOVE_HEAD(&straight, co_scheduled_next);
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trace_aio_co_schedule_bh_cb(ctx, co);
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aio_context_acquire(ctx);
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/* Protected by write barrier in qemu_aio_coroutine_enter */
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qatomic_set(&co->scheduled, NULL);
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qemu_aio_coroutine_enter(ctx, co);
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aio_context_release(ctx);
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}
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}
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AioContext *aio_context_new(Error **errp)
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{
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int ret;
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AioContext *ctx;
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ctx = (AioContext *) g_source_new(&aio_source_funcs, sizeof(AioContext));
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QSLIST_INIT(&ctx->bh_list);
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QSIMPLEQ_INIT(&ctx->bh_slice_list);
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aio_context_setup(ctx);
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ret = event_notifier_init(&ctx->notifier, false);
|
|
if (ret < 0) {
|
|
error_setg_errno(errp, -ret, "Failed to initialize event notifier");
|
|
goto fail;
|
|
}
|
|
g_source_set_can_recurse(&ctx->source, true);
|
|
qemu_lockcnt_init(&ctx->list_lock);
|
|
|
|
ctx->co_schedule_bh = aio_bh_new(ctx, co_schedule_bh_cb, ctx);
|
|
QSLIST_INIT(&ctx->scheduled_coroutines);
|
|
|
|
aio_set_event_notifier(ctx, &ctx->notifier,
|
|
false,
|
|
aio_context_notifier_cb,
|
|
aio_context_notifier_poll,
|
|
aio_context_notifier_poll_ready);
|
|
#ifdef CONFIG_LINUX_AIO
|
|
ctx->linux_aio = NULL;
|
|
#endif
|
|
|
|
#ifdef CONFIG_LINUX_IO_URING
|
|
ctx->linux_io_uring = NULL;
|
|
#endif
|
|
|
|
ctx->thread_pool = NULL;
|
|
qemu_rec_mutex_init(&ctx->lock);
|
|
timerlistgroup_init(&ctx->tlg, aio_timerlist_notify, ctx);
|
|
|
|
ctx->poll_ns = 0;
|
|
ctx->poll_max_ns = 0;
|
|
ctx->poll_grow = 0;
|
|
ctx->poll_shrink = 0;
|
|
|
|
ctx->aio_max_batch = 0;
|
|
|
|
return ctx;
|
|
fail:
|
|
g_source_destroy(&ctx->source);
|
|
return NULL;
|
|
}
|
|
|
|
void aio_co_schedule(AioContext *ctx, Coroutine *co)
|
|
{
|
|
trace_aio_co_schedule(ctx, co);
|
|
const char *scheduled = qatomic_cmpxchg(&co->scheduled, NULL,
|
|
__func__);
|
|
|
|
if (scheduled) {
|
|
fprintf(stderr,
|
|
"%s: Co-routine was already scheduled in '%s'\n",
|
|
__func__, scheduled);
|
|
abort();
|
|
}
|
|
|
|
/* The coroutine might run and release the last ctx reference before we
|
|
* invoke qemu_bh_schedule(). Take a reference to keep ctx alive until
|
|
* we're done.
|
|
*/
|
|
aio_context_ref(ctx);
|
|
|
|
QSLIST_INSERT_HEAD_ATOMIC(&ctx->scheduled_coroutines,
|
|
co, co_scheduled_next);
|
|
qemu_bh_schedule(ctx->co_schedule_bh);
|
|
|
|
aio_context_unref(ctx);
|
|
}
|
|
|
|
typedef struct AioCoRescheduleSelf {
|
|
Coroutine *co;
|
|
AioContext *new_ctx;
|
|
} AioCoRescheduleSelf;
|
|
|
|
static void aio_co_reschedule_self_bh(void *opaque)
|
|
{
|
|
AioCoRescheduleSelf *data = opaque;
|
|
aio_co_schedule(data->new_ctx, data->co);
|
|
}
|
|
|
|
void coroutine_fn aio_co_reschedule_self(AioContext *new_ctx)
|
|
{
|
|
AioContext *old_ctx = qemu_get_current_aio_context();
|
|
|
|
if (old_ctx != new_ctx) {
|
|
AioCoRescheduleSelf data = {
|
|
.co = qemu_coroutine_self(),
|
|
.new_ctx = new_ctx,
|
|
};
|
|
/*
|
|
* We can't directly schedule the coroutine in the target context
|
|
* because this would be racy: The other thread could try to enter the
|
|
* coroutine before it has yielded in this one.
|
|
*/
|
|
aio_bh_schedule_oneshot(old_ctx, aio_co_reschedule_self_bh, &data);
|
|
qemu_coroutine_yield();
|
|
}
|
|
}
|
|
|
|
void aio_co_wake(struct Coroutine *co)
|
|
{
|
|
AioContext *ctx;
|
|
|
|
/* Read coroutine before co->ctx. Matches smp_wmb in
|
|
* qemu_coroutine_enter.
|
|
*/
|
|
smp_read_barrier_depends();
|
|
ctx = qatomic_read(&co->ctx);
|
|
|
|
aio_co_enter(ctx, co);
|
|
}
|
|
|
|
void aio_co_enter(AioContext *ctx, struct Coroutine *co)
|
|
{
|
|
if (ctx != qemu_get_current_aio_context()) {
|
|
aio_co_schedule(ctx, co);
|
|
return;
|
|
}
|
|
|
|
if (qemu_in_coroutine()) {
|
|
Coroutine *self = qemu_coroutine_self();
|
|
assert(self != co);
|
|
QSIMPLEQ_INSERT_TAIL(&self->co_queue_wakeup, co, co_queue_next);
|
|
} else {
|
|
aio_context_acquire(ctx);
|
|
qemu_aio_coroutine_enter(ctx, co);
|
|
aio_context_release(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)
|
|
{
|
|
qemu_rec_mutex_lock(&ctx->lock);
|
|
}
|
|
|
|
void aio_context_release(AioContext *ctx)
|
|
{
|
|
qemu_rec_mutex_unlock(&ctx->lock);
|
|
}
|
|
|
|
static __thread AioContext *my_aiocontext;
|
|
|
|
AioContext *qemu_get_current_aio_context(void)
|
|
{
|
|
if (my_aiocontext) {
|
|
return my_aiocontext;
|
|
}
|
|
if (qemu_mutex_iothread_locked()) {
|
|
/* Possibly in a vCPU thread. */
|
|
return qemu_get_aio_context();
|
|
}
|
|
return NULL;
|
|
}
|
|
|
|
void qemu_set_current_aio_context(AioContext *ctx)
|
|
{
|
|
assert(!my_aiocontext);
|
|
my_aiocontext = ctx;
|
|
}
|