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. */ 37 if (atomic_read(&wait->num_waiters)) { 38 aio_bh_schedule_oneshot(qemu_get_aio_context(), dummy_bh_cb, NULL); 39 } 40 } 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 } 72