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c40a254570
qemu_aio_coroutine_enter() is (indirectly) called recursively when processing co_queue_wakeup. This can lead to stack exhaustion. This patch rewrites co_queue_wakeup in an iterative fashion (instead of recursive) with bounded memory usage to prevent stack exhaustion. qemu_co_queue_run_restart() is inlined into qemu_aio_coroutine_enter() and the qemu_coroutine_enter() call is turned into a loop to avoid recursion. There is one change that is worth mentioning: Previously, when coroutine A queued coroutine B, qemu_co_queue_run_restart() entered coroutine B from coroutine A. If A was terminating then it would still stay alive until B yielded. After this patch B is entered by A's parent so that a A can be deleted immediately if it is terminating. It is safe to make this change since B could never interact with A if it was terminating anyway. Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com> Reviewed-by: Paolo Bonzini <pbonzini@redhat.com> Message-id: 20180322152834.12656-3-stefanha@redhat.com Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
73 lines
2.3 KiB
C
73 lines
2.3 KiB
C
/*
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* Coroutine internals
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*
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* Copyright (c) 2011 Kevin Wolf <kwolf@redhat.com>
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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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#ifndef QEMU_COROUTINE_INT_H
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#define QEMU_COROUTINE_INT_H
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#include "qemu/queue.h"
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#include "qemu/coroutine.h"
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#define COROUTINE_STACK_SIZE (1 << 20)
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typedef enum {
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COROUTINE_YIELD = 1,
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COROUTINE_TERMINATE = 2,
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COROUTINE_ENTER = 3,
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} CoroutineAction;
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struct Coroutine {
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CoroutineEntry *entry;
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void *entry_arg;
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Coroutine *caller;
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/* Only used when the coroutine has terminated. */
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QSLIST_ENTRY(Coroutine) pool_next;
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size_t locks_held;
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/* Only used when the coroutine has yielded. */
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AioContext *ctx;
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/* Used to catch and abort on illegal co-routine entry.
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* Will contain the name of the function that had first
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* scheduled the coroutine. */
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const char *scheduled;
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QSIMPLEQ_ENTRY(Coroutine) co_queue_next;
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/* Coroutines that should be woken up when we yield or terminate.
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* Only used when the coroutine is running.
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*/
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QSIMPLEQ_HEAD(, Coroutine) co_queue_wakeup;
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QSLIST_ENTRY(Coroutine) co_scheduled_next;
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};
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Coroutine *qemu_coroutine_new(void);
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void qemu_coroutine_delete(Coroutine *co);
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CoroutineAction qemu_coroutine_switch(Coroutine *from, Coroutine *to,
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CoroutineAction action);
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#endif
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