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[93.34.169.1]) by mx.google.com with ESMTPS id sz6sm2445230pbc.52.2012.10.31.08.31.59 (version=TLSv1/SSLv3 cipher=OTHER); Wed, 31 Oct 2012 08:32:02 -0700 (PDT) From: Paolo Bonzini To: qemu-devel@nongnu.org Date: Wed, 31 Oct 2012 16:30:31 +0100 Message-Id: <1351697456-16107-15-git-send-email-pbonzini@redhat.com> X-Mailer: git-send-email 1.7.12.1 In-Reply-To: <1351697456-16107-1-git-send-email-pbonzini@redhat.com> References: <1351697456-16107-1-git-send-email-pbonzini@redhat.com> X-detected-operating-system: by eggs.gnu.org: Genre and OS details not recognized. X-Received-From: 209.85.220.45 Cc: aliguori@us.ibm.com, stefanha@redhat.com Subject: [Qemu-devel] [PATCH v2 14/39] event_notifier: enable it to use pipes X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.14 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org Sender: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org This takes the eventfd emulation code from the main loop. When the EventNotifier is used for the main loop too, we need this compatibility code. Without CONFIG_EVENTFD, event_notifier_get_fd is only usable for the "read" side of the notifier, for example to set a select() handler. The return value of event_notifier_set changes to the cleaner 0/-errno. No caller is actually checking the return value. Reviewed-by: Anthony Liguori Signed-off-by: Paolo Bonzini --- event_notifier-posix.c | 85 ++++++++++++++++++++++++++++++++++++++++---------- event_notifier.h | 3 +- 2 file modificati, 71 inserzioni(+), 17 rimozioni(-) diff --git a/event_notifier-posix.c b/event_notifier-posix.c index 2c207e1..6f3239a 100644 --- a/event_notifier-posix.c +++ b/event_notifier-posix.c @@ -20,48 +20,101 @@ void event_notifier_init_fd(EventNotifier *e, int fd) { - e->fd = fd; + e->rfd = fd; + e->wfd = fd; } int event_notifier_init(EventNotifier *e, int active) { + int fds[2]; + int ret; + #ifdef CONFIG_EVENTFD - int fd = eventfd(!!active, EFD_NONBLOCK | EFD_CLOEXEC); - if (fd < 0) - return -errno; - e->fd = fd; - return 0; + ret = eventfd(0, EFD_NONBLOCK | EFD_CLOEXEC); #else - return -ENOSYS; + ret = -1; + errno = ENOSYS; #endif + if (ret >= 0) { + e->rfd = e->wfd = ret; + } else { + if (errno != ENOSYS) { + return -errno; + } + if (qemu_pipe(fds) < 0) { + return -errno; + } + ret = fcntl_setfl(fds[0], O_NONBLOCK); + if (ret < 0) { + ret = -errno; + goto fail; + } + ret = fcntl_setfl(fds[1], O_NONBLOCK); + if (ret < 0) { + ret = -errno; + goto fail; + } + e->rfd = fds[0]; + e->wfd = fds[1]; + } + if (active) { + event_notifier_set(e); + } + return 0; + +fail: + close(fds[0]); + close(fds[1]); + return ret; } void event_notifier_cleanup(EventNotifier *e) { - close(e->fd); + if (e->rfd != e->wfd) { + close(e->rfd); + } + close(e->wfd); } int event_notifier_get_fd(EventNotifier *e) { - return e->fd; + return e->rfd; } int event_notifier_set_handler(EventNotifier *e, EventNotifierHandler *handler) { - return qemu_set_fd_handler(e->fd, (IOHandler *)handler, NULL, e); + return qemu_set_fd_handler(e->rfd, (IOHandler *)handler, NULL, e); } int event_notifier_set(EventNotifier *e) { - uint64_t value = 1; - int r = write(e->fd, &value, sizeof(value)); - return r == sizeof(value); + static const uint64_t value = 1; + ssize_t ret; + + do { + ret = write(e->wfd, &value, sizeof(value)); + } while (ret < 0 && errno == EINTR); + + /* EAGAIN is fine, a read must be pending. */ + if (ret < 0 && errno != EAGAIN) { + return -errno; + } + return 0; } int event_notifier_test_and_clear(EventNotifier *e) { - uint64_t value; - int r = read(e->fd, &value, sizeof(value)); - return r == sizeof(value); + int value; + ssize_t len; + char buffer[512]; + + /* Drain the notify pipe. For eventfd, only 8 bytes will be read. */ + value = 0; + do { + len = read(e->rfd, buffer, sizeof(buffer)); + value |= (len > 0); + } while ((len == -1 && errno == EINTR) || len == sizeof(buffer)); + + return value; } diff --git a/event_notifier.h b/event_notifier.h index b283a49..88b57af 100644 --- a/event_notifier.h +++ b/event_notifier.h @@ -23,7 +23,8 @@ struct EventNotifier { #ifdef _WIN32 HANDLE event; #else - int fd; + int rfd; + int wfd; #endif };