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 AioWait global_aio_wait; 30 31 static void dummy_bh_cb(void *opaque) 32 { 33 /* The point is to make AIO_WAIT_WHILE()'s aio_poll() return */ 34 } 35 36 void aio_wait_kick(void) 37 { 38 /* The barrier (or an atomic op) is in the caller. */ 39 if (qatomic_read(&global_aio_wait.num_waiters)) { 40 aio_bh_schedule_oneshot(qemu_get_aio_context(), dummy_bh_cb, NULL); 41 } 42 } 43 44 typedef struct { 45 bool done; 46 QEMUBHFunc *cb; 47 void *opaque; 48 } AioWaitBHData; 49 50 /* Context: BH in IOThread */ 51 static void aio_wait_bh(void *opaque) 52 { 53 AioWaitBHData *data = opaque; 54 55 data->cb(data->opaque); 56 57 data->done = true; 58 aio_wait_kick(); 59 } 60 61 void aio_wait_bh_oneshot(AioContext *ctx, QEMUBHFunc *cb, void *opaque) 62 { 63 AioWaitBHData data = { 64 .cb = cb, 65 .opaque = opaque, 66 }; 67 68 assert(qemu_get_current_aio_context() == qemu_get_aio_context()); 69 70 aio_bh_schedule_oneshot(ctx, aio_wait_bh, &data); 71 AIO_WAIT_WHILE(ctx, !data.done); 72 } 73