From patchwork Tue Sep 15 12:03:38 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Stefan Hajnoczi X-Patchwork-Id: 273734 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-9.6 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH, MAILING_LIST_MULTI, SIGNED_OFF_BY, SPF_HELO_NONE, SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 4E6D0C43461 for ; Tue, 15 Sep 2020 12:05:45 +0000 (UTC) Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id C0265206B2 for ; Tue, 15 Sep 2020 12:05:44 +0000 (UTC) Authentication-Results: mail.kernel.org; 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Tue, 15 Sep 2020 12:03:42 +0000 (UTC) Received: from localhost (ovpn-112-192.ams2.redhat.com [10.36.112.192]) by smtp.corp.redhat.com (Postfix) with ESMTP id 5066B51574; Tue, 15 Sep 2020 12:03:42 +0000 (UTC) From: Stefan Hajnoczi To: qemu-devel@nongnu.org Subject: [PATCH v2 1/2] fdmon-poll: reset npfd when upgrading to fdmon-epoll Date: Tue, 15 Sep 2020 13:03:38 +0100 Message-Id: <20200915120339.702938-2-stefanha@redhat.com> In-Reply-To: <20200915120339.702938-1-stefanha@redhat.com> References: <20200915120339.702938-1-stefanha@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.16 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=stefanha@redhat.com X-Mimecast-Spam-Score: 0.002 X-Mimecast-Originator: redhat.com Received-SPF: pass client-ip=63.128.21.124; envelope-from=stefanha@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-detected-operating-system: by eggs.gnu.org: First seen = 2020/09/15 02:23:19 X-ACL-Warn: Detected OS = Linux 2.2.x-3.x [generic] [fuzzy] X-Spam_score_int: -50 X-Spam_score: -5.1 X-Spam_bar: ----- X-Spam_report: (-5.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-2.999, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H5=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Fam Zheng , qemu-block@nongnu.org, =?utf-8?q?Philippe_?= =?utf-8?q?Mathieu-Daud=C3=A9?= , qemu-stable@nongnu.org, Stefan Hajnoczi Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" npfd keeps track of how many pollfds are currently being monitored. It must be reset to 0 when fdmon_poll_wait() returns. When npfd reaches a treshold we switch to fdmon-epoll because it scales better. This patch resets npfd in the case where we switch to fdmon-epoll. Forgetting to do so results in the following assertion failure: util/fdmon-poll.c:65: fdmon_poll_wait: Assertion `npfd == 0' failed. Buglink: https://bugzilla.redhat.com/show_bug.cgi?id=1869952 Fixes: 1f050a4690f62a1e7dabc4f44141e9f762c3769f ("aio-posix: extract ppoll(2) and epoll(7) fd monitoring") Reviewed-by: Philippe Mathieu-Daudé Signed-off-by: Stefan Hajnoczi --- util/fdmon-poll.c | 1 + 1 file changed, 1 insertion(+) diff --git a/util/fdmon-poll.c b/util/fdmon-poll.c index 488067b679..5fe3b47865 100644 --- a/util/fdmon-poll.c +++ b/util/fdmon-poll.c @@ -73,6 +73,7 @@ static int fdmon_poll_wait(AioContext *ctx, AioHandlerList *ready_list, /* epoll(7) is faster above a certain number of fds */ if (fdmon_epoll_try_upgrade(ctx, npfd)) { + npfd = 0; /* we won't need pollfds[], reset npfd */ return ctx->fdmon_ops->wait(ctx, ready_list, timeout); }