1 /* 2 * event notifier support 3 * 4 * Copyright Red Hat, Inc. 2010 5 * 6 * Authors: 7 * Michael S. Tsirkin <mst@redhat.com> 8 * 9 * This work is licensed under the terms of the GNU GPL, version 2 or later. 10 * See the COPYING file in the top-level directory. 11 */ 12 13 #include "qemu/osdep.h" 14 #include "qemu-common.h" 15 #include "qemu/cutils.h" 16 #include "qemu/event_notifier.h" 17 #include "sysemu/char.h" 18 #include "qemu/main-loop.h" 19 20 #ifdef CONFIG_EVENTFD 21 #include <sys/eventfd.h> 22 #endif 23 24 void event_notifier_init_fd(EventNotifier *e, int fd) 25 { 26 e->rfd = fd; 27 e->wfd = fd; 28 } 29 30 int event_notifier_init(EventNotifier *e, int active) 31 { 32 int fds[2]; 33 int ret; 34 35 #ifdef CONFIG_EVENTFD 36 ret = eventfd(0, EFD_NONBLOCK | EFD_CLOEXEC); 37 #else 38 ret = -1; 39 errno = ENOSYS; 40 #endif 41 if (ret >= 0) { 42 e->rfd = e->wfd = ret; 43 } else { 44 if (errno != ENOSYS) { 45 return -errno; 46 } 47 if (qemu_pipe(fds) < 0) { 48 return -errno; 49 } 50 ret = fcntl_setfl(fds[0], O_NONBLOCK); 51 if (ret < 0) { 52 ret = -errno; 53 goto fail; 54 } 55 ret = fcntl_setfl(fds[1], O_NONBLOCK); 56 if (ret < 0) { 57 ret = -errno; 58 goto fail; 59 } 60 e->rfd = fds[0]; 61 e->wfd = fds[1]; 62 } 63 if (active) { 64 event_notifier_set(e); 65 } 66 return 0; 67 68 fail: 69 close(fds[0]); 70 close(fds[1]); 71 return ret; 72 } 73 74 void event_notifier_cleanup(EventNotifier *e) 75 { 76 if (e->rfd != e->wfd) { 77 close(e->rfd); 78 } 79 close(e->wfd); 80 } 81 82 int event_notifier_get_fd(const EventNotifier *e) 83 { 84 return e->rfd; 85 } 86 87 int event_notifier_set_handler(EventNotifier *e, 88 EventNotifierHandler *handler) 89 { 90 qemu_set_fd_handler(e->rfd, (IOHandler *)handler, NULL, e); 91 return 0; 92 } 93 94 int event_notifier_set(EventNotifier *e) 95 { 96 static const uint64_t value = 1; 97 ssize_t ret; 98 99 do { 100 ret = write(e->wfd, &value, sizeof(value)); 101 } while (ret < 0 && errno == EINTR); 102 103 /* EAGAIN is fine, a read must be pending. */ 104 if (ret < 0 && errno != EAGAIN) { 105 return -errno; 106 } 107 return 0; 108 } 109 110 int event_notifier_test_and_clear(EventNotifier *e) 111 { 112 int value; 113 ssize_t len; 114 char buffer[512]; 115 116 /* Drain the notify pipe. For eventfd, only 8 bytes will be read. */ 117 value = 0; 118 do { 119 len = read(e->rfd, buffer, sizeof(buffer)); 120 value |= (len > 0); 121 } while ((len == -1 && errno == EINTR) || len == sizeof(buffer)); 122 123 return value; 124 } 125