From patchwork Tue Feb 9 11:46:12 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Paolo Bonzini X-Patchwork-Id: 8260631 Return-Path: X-Original-To: patchwork-qemu-devel@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork2.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.136]) by patchwork2.web.kernel.org (Postfix) with ESMTP id 9699EBEEE5 for ; Tue, 9 Feb 2016 11:59:18 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id BACFF2025A for ; Tue, 9 Feb 2016 11:59:17 +0000 (UTC) Received: from lists.gnu.org (lists.gnu.org [208.118.235.17]) (using TLSv1 with cipher AES256-SHA (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id AEDBF2022D for ; Tue, 9 Feb 2016 11:59:16 +0000 (UTC) Received: from localhost ([::1]:54823 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1aT6wu-00054x-5U for patchwork-qemu-devel@patchwork.kernel.org; Tue, 09 Feb 2016 06:59:16 -0500 Received: from eggs.gnu.org ([2001:4830:134:3::10]:37772) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1aT6kl-0006nr-Ok for qemu-devel@nongnu.org; Tue, 09 Feb 2016 06:46:45 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1aT6kk-0005KR-Cm for qemu-devel@nongnu.org; Tue, 09 Feb 2016 06:46:43 -0500 Received: from mx1.redhat.com ([209.132.183.28]:57012) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1aT6kk-0005KD-44 for qemu-devel@nongnu.org; Tue, 09 Feb 2016 06:46:42 -0500 Received: from int-mx09.intmail.prod.int.phx2.redhat.com (int-mx09.intmail.prod.int.phx2.redhat.com [10.5.11.22]) by mx1.redhat.com (Postfix) with ESMTPS id BBE928E3E3 for ; Tue, 9 Feb 2016 11:46:41 +0000 (UTC) Received: from donizetti.redhat.com (ovpn-112-47.ams2.redhat.com [10.36.112.47]) by int-mx09.intmail.prod.int.phx2.redhat.com (8.14.4/8.14.4) with ESMTP id u19BkELw002965; Tue, 9 Feb 2016 06:46:40 -0500 From: Paolo Bonzini To: qemu-devel@nongnu.org Date: Tue, 9 Feb 2016 12:46:12 +0100 Message-Id: <1455018374-4706-15-git-send-email-pbonzini@redhat.com> In-Reply-To: <1455018374-4706-1-git-send-email-pbonzini@redhat.com> References: <1455018374-4706-1-git-send-email-pbonzini@redhat.com> X-Scanned-By: MIMEDefang 2.68 on 10.5.11.22 X-detected-operating-system: by eggs.gnu.org: GNU/Linux 3.x X-Received-From: 209.132.183.28 Cc: stefanha@redhat.com Subject: [Qemu-devel] [PATCH 14/16] aio-win32: remove walking_handlers, protecting AioHandler list with list_lock 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+patchwork-qemu-devel=patchwork.kernel.org@nongnu.org Sender: qemu-devel-bounces+patchwork-qemu-devel=patchwork.kernel.org@nongnu.org X-Spam-Status: No, score=-6.9 required=5.0 tests=BAYES_00, RCVD_IN_DNSWL_HI, UNPARSEABLE_RELAY autolearn=unavailable version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on mail.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP Signed-off-by: Paolo Bonzini --- aio-win32.c | 81 +++++++++++++++++++++++++++++++++++++------------------------ 1 file changed, 49 insertions(+), 32 deletions(-) diff --git a/aio-win32.c b/aio-win32.c index f1a8780..862f48c 100644 --- a/aio-win32.c +++ b/aio-win32.c @@ -43,6 +43,7 @@ void aio_set_fd_handler(AioContext *ctx, /* fd is a SOCKET in our case */ AioHandler *node; + qemu_lockcnt_lock(&ctx->list_lock); QLIST_FOREACH(node, &ctx->aio_handlers, node) { if (node->pfd.fd == fd && !node->deleted) { break; @@ -52,14 +53,14 @@ void aio_set_fd_handler(AioContext *ctx, /* Are we deleting the fd handler? */ if (!io_read && !io_write) { if (node) { - /* If the lock is held, just mark the node as deleted */ - if (ctx->walking_handlers) { + /* If aio_poll is in progress, just mark the node as deleted */ + if (qemu_lockcnt_count(&ctx->list_lock)) { node->deleted = 1; node->pfd.revents = 0; } else { /* Otherwise, delete it for real. We can't just mark it as * deleted because deleted nodes are only cleaned up after - * releasing the walking_handlers lock. + * releasing the list_lock. */ QLIST_REMOVE(node, node); g_free(node); @@ -72,7 +73,7 @@ void aio_set_fd_handler(AioContext *ctx, /* Alloc and insert if it's not already there */ node = g_new0(AioHandler, 1); node->pfd.fd = fd; - QLIST_INSERT_HEAD(&ctx->aio_handlers, node, node); + QLIST_INSERT_HEAD_RCU(&ctx->aio_handlers, node, node); } node->pfd.events = 0; @@ -97,6 +98,7 @@ void aio_set_fd_handler(AioContext *ctx, FD_CONNECT | FD_WRITE | FD_OOB); } + qemu_lockcnt_unlock(&ctx->list_lock); aio_notify(ctx); } @@ -107,6 +109,7 @@ void aio_set_event_notifier(AioContext *ctx, { AioHandler *node; + qemu_lockcnt_lock(&ctx->list_lock); QLIST_FOREACH(node, &ctx->aio_handlers, node) { if (node->e == e && !node->deleted) { break; @@ -118,14 +121,14 @@ void aio_set_event_notifier(AioContext *ctx, if (node) { g_source_remove_poll(&ctx->source, &node->pfd); - /* If the lock is held, just mark the node as deleted */ - if (ctx->walking_handlers) { + /* aio_poll is in progress, just mark the node as deleted */ + if (qemu_lockcnt_count(&ctx->list_lock)) { node->deleted = 1; node->pfd.revents = 0; } else { /* Otherwise, delete it for real. We can't just mark it as * deleted because deleted nodes are only cleaned up after - * releasing the walking_handlers lock. + * releasing the list_lock. */ QLIST_REMOVE(node, node); g_free(node); @@ -139,7 +142,7 @@ void aio_set_event_notifier(AioContext *ctx, node->pfd.fd = (uintptr_t)event_notifier_get_handle(e); node->pfd.events = G_IO_IN; node->is_external = is_external; - QLIST_INSERT_HEAD(&ctx->aio_handlers, node, node); + QLIST_INSERT_HEAD_RCU(&ctx->aio_handlers, node, node); g_source_add_poll(&ctx->source, &node->pfd); } @@ -147,6 +150,7 @@ void aio_set_event_notifier(AioContext *ctx, node->io_notify = io_notify; } + qemu_lockcnt_unlock(&ctx->list_lock); aio_notify(ctx); } @@ -157,10 +161,16 @@ bool aio_prepare(AioContext *ctx) bool have_select_revents = false; fd_set rfds, wfds; + /* + * We have to walk very carefully in case aio_set_fd_handler is + * called while we're walking. + */ + qemu_lockcnt_inc(&ctx->list_lock); + /* fill fd sets */ FD_ZERO(&rfds); FD_ZERO(&wfds); - QLIST_FOREACH(node, &ctx->aio_handlers, node) { + QLIST_FOREACH_RCU(node, &ctx->aio_handlers, node) { if (node->io_read) { FD_SET ((SOCKET)node->pfd.fd, &rfds); } @@ -170,61 +180,71 @@ bool aio_prepare(AioContext *ctx) } if (select(0, &rfds, &wfds, NULL, &tv0) > 0) { - QLIST_FOREACH(node, &ctx->aio_handlers, node) { - node->pfd.revents = 0; + QLIST_FOREACH_RCU(node, &ctx->aio_handlers, node) { if (FD_ISSET(node->pfd.fd, &rfds)) { - node->pfd.revents |= G_IO_IN; + atomic_or(&node->pfd.revents, G_IO_IN); have_select_revents = true; } if (FD_ISSET(node->pfd.fd, &wfds)) { - node->pfd.revents |= G_IO_OUT; + atomic_or(&node->pfd.revents, G_IO_OUT); have_select_revents = true; } } } + qemu_lockcnt_dec(&ctx->list_lock); return have_select_revents; } bool aio_pending(AioContext *ctx) { AioHandler *node; + bool result = false; - QLIST_FOREACH(node, &ctx->aio_handlers, node) { + /* + * We have to walk very carefully in case aio_set_fd_handler is + * called while we're walking. + */ + qemu_lockcnt_inc(&ctx->list_lock); + QLIST_FOREACH_RCU(node, &ctx->aio_handlers, node) { if (node->pfd.revents && node->io_notify) { - return true; + result = true; + break; } if ((node->pfd.revents & G_IO_IN) && node->io_read) { - return true; + result = true; + break; } if ((node->pfd.revents & G_IO_OUT) && node->io_write) { - return true; + result = true; + break; } } - return false; + qemu_lockcnt_dec(&ctx->list_lock); + return result; } static bool aio_dispatch_handlers(AioContext *ctx, HANDLE event) { - AioHandler *node, *tmp; + AioHandler *node; bool progress = false; - ctx->walking_handlers++; + qemu_lockcnt_inc(&ctx->list_lock); /* * We have to walk very carefully in case aio_set_fd_handler is * called while we're walking. */ - QLIST_FOREACH_SAFE(node, &ctx->aio_handlers, node, tmp) { - int revents = node->pfd.revents; + QLIST_FOREACH_SAFE_RCU(node, &ctx->aio_handlers, node, tmp) { + AioHandler *tmp; + int revents = atomic_xchg(&node->pfd.revents, 0); if (!node->deleted && (revents || event_notifier_get_handle(node->e) == event) && node->io_notify) { - node->pfd.revents = 0; node->io_notify(node->e); /* aio_notify() does not count as progress */ @@ -235,7 +255,6 @@ static bool aio_dispatch_handlers(AioContext *ctx, HANDLE event) if (!node->deleted && (node->io_read || node->io_write)) { - node->pfd.revents = 0; if ((revents & G_IO_IN) && node->io_read) { node->io_read(node->opaque); progress = true; @@ -256,16 +275,15 @@ static bool aio_dispatch_handlers(AioContext *ctx, HANDLE event) } if (node->deleted) { - ctx->walking_handlers--; - if (!ctx->walking_handlers) { + if (qemu_lockcnt_dec_if_lock(&ctx->list_lock)) { QLIST_REMOVE(node, node); g_free(node); + qemu_lockcnt_inc_and_unlock(&ctx->list_lock); } - ctx->walking_handlers++; } } - ctx->walking_handlers--; + qemu_lockcnt_dec(&ctx->list_lock); return progress; } @@ -301,20 +319,19 @@ bool aio_poll_internal(AioContext *ctx, bool blocking) atomic_add(&ctx->notify_me, 2); } + qemu_lockcnt_inc(&ctx->list_lock); have_select_revents = aio_prepare(ctx); - ctx->walking_handlers++; - /* fill fd sets */ count = 0; - QLIST_FOREACH(node, &ctx->aio_handlers, node) { + QLIST_FOREACH_RCU(node, &ctx->aio_handlers, node) { if (!node->deleted && node->io_notify && aio_node_check(ctx, node->is_external)) { events[count++] = event_notifier_get_handle(node->e); } } - ctx->walking_handlers--; + qemu_lockcnt_dec(&ctx->list_lock); first = true; /* ctx->notifier is always registered. */