[qemu.git] / util / aio-wait.c

/*
 * AioContext wait support
 *
 * Copyright (C) 2018 Red Hat, Inc.
 *
 * 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/osdep.h"
#include "qemu/main-loop.h"
#include "block/aio-wait.h"

static void dummy_bh_cb(void *opaque)
{
    /* The point is to make AIO_WAIT_WHILE()'s aio_poll() return */
}

void aio_wait_kick(AioWait *wait)
{
    /* The barrier (or an atomic op) is in the caller.  */
    if (atomic_read(&wait->num_waiters)) {
        aio_bh_schedule_oneshot(qemu_get_aio_context(), dummy_bh_cb, NULL);
    }
}

typedef struct {
    AioWait wait;
    bool done;
    QEMUBHFunc *cb;
    void *opaque;
} AioWaitBHData;

/* Context: BH in IOThread */
static void aio_wait_bh(void *opaque)
{
    AioWaitBHData *data = opaque;

    data->cb(data->opaque);

    data->done = true;
    aio_wait_kick(&data->wait);
}

void aio_wait_bh_oneshot(AioContext *ctx, QEMUBHFunc *cb, void *opaque)
{
    AioWaitBHData data = {
        .cb = cb,
        .opaque = opaque,
    };

    assert(qemu_get_current_aio_context() == qemu_get_aio_context());

    aio_bh_schedule_oneshot(ctx, aio_wait_bh, &data);
    AIO_WAIT_WHILE(&data.wait, ctx, !data.done);
}
Commit	Line	Data
7719f3c9 SH	1	/*
	2	* AioContext wait support
	3	*
	4	* Copyright (C) 2018 Red Hat, Inc.
	5	*
	6	* Permission is hereby granted, free of charge, to any person obtaining a copy
	7	* of this software and associated documentation files (the "Software"), to deal
	8	* in the Software without restriction, including without limitation the rights
	9	* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
	10	* copies of the Software, and to permit persons to whom the Software is
	11	* furnished to do so, subject to the following conditions:
	12	*
	13	* The above copyright notice and this permission notice shall be included in
	14	* all copies or substantial portions of the Software.
	15	*
	16	* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
	17	* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
	18	* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
	19	* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
	20	* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
	21	* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
	22	* THE SOFTWARE.
	23	*/
	24
	25	#include "qemu/osdep.h"
	26	#include "qemu/main-loop.h"
	27	#include "block/aio-wait.h"
	28
	29	static void dummy_bh_cb(void *opaque)
	30	{
	31	/* The point is to make AIO_WAIT_WHILE()'s aio_poll() return */
	32	}
	33
	34	void aio_wait_kick(AioWait *wait)
	35	{
	36	/* The barrier (or an atomic op) is in the caller. */
7376eda7	37	if (atomic_read(&wait->num_waiters)) {
7719f3c9 SH	38	aio_bh_schedule_oneshot(qemu_get_aio_context(), dummy_bh_cb, NULL);
	39	}
	40	}
b89d92f3 SH	41
	42	typedef struct {
	43	AioWait wait;
	44	bool done;
	45	QEMUBHFunc *cb;
	46	void *opaque;
	47	} AioWaitBHData;
	48
	49	/* Context: BH in IOThread */
	50	static void aio_wait_bh(void *opaque)
	51	{
	52	AioWaitBHData *data = opaque;
	53
	54	data->cb(data->opaque);
	55
	56	data->done = true;
	57	aio_wait_kick(&data->wait);
	58	}
	59
	60	void aio_wait_bh_oneshot(AioContext ctx, QEMUBHFunc cb, void *opaque)
	61	{
	62	AioWaitBHData data = {
	63	.cb = cb,
	64	.opaque = opaque,
	65	};
	66
	67	assert(qemu_get_current_aio_context() == qemu_get_aio_context());
	68
	69	aio_bh_schedule_oneshot(ctx, aio_wait_bh, &data);
	70	AIO_WAIT_WHILE(&data.wait, ctx, !data.done);
	71	}