From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id F2C3EC6FD1D for ; Mon, 27 Mar 2023 18:23:15 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232384AbjC0SXO (ORCPT ); Mon, 27 Mar 2023 14:23:14 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:33938 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232345AbjC0SXJ (ORCPT ); Mon, 27 Mar 2023 14:23:09 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [IPv6:2604:1380:4601:e00::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 6D42840CB; Mon, 27 Mar 2023 11:23:07 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id 2D8AAB818BC; Mon, 27 Mar 2023 18:23:06 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 862A2C433D2; Mon, 27 Mar 2023 18:23:03 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1679941384; bh=TNJCOio1Rm6H8bH6XbJFRUE6Yg7Pb43dg5K5QcL0diU=; h=From:Date:Subject:References:In-Reply-To:To:Cc:From; b=b0HvNd+kZXtHoSvHRENpxlIo2kjAYayuM/+3si5bBEC36OZkhZUW2/inUkkkFVCxs H07NhvpfLfKGc4cK58iwpJj/IkdfExLaojRh922UIhw/6VN+sxg0Y/az7zEbam6lW4 C3ZA+WOAw/D7ZwSX/tpE0FM6Pr/neMD5TmPPrJBQcFpBasTxHFPbwj1TLJWzRjM5CD 18RaqYriL3gw6QgWHnR63hFEajKTgQPSjPMN9VkAoVKxKIC2FEhJicVJEflplJX1oK b75bdavBWF5hoESSnaZSyGpiO1HwUA7JOqVc5EB9KtHK9CfVcx2sqkmDdgWTYGcxA+ 2D0pX/PGRvruQ== From: Christian Brauner Date: Mon, 27 Mar 2023 20:22:53 +0200 Subject: [PATCH 3/3] fanotify: use pidfd_prepare() MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Message-Id: <20230327-pidfd-file-api-v1-3-5c0e9a3158e4@kernel.org> References: <20230327-pidfd-file-api-v1-0-5c0e9a3158e4@kernel.org> In-Reply-To: <20230327-pidfd-file-api-v1-0-5c0e9a3158e4@kernel.org> To: linux-fsdevel@vger.kernel.org Cc: Jan Kara , Amir Goldstein , Matthew Bobrowski , linux-kernel@vger.kernel.org, Christian Brauner X-Mailer: b4 0.13-dev-00303 X-Developer-Signature: v=1; a=openpgp-sha256; l=2293; i=brauner@kernel.org; h=from:subject:message-id; bh=TNJCOio1Rm6H8bH6XbJFRUE6Yg7Pb43dg5K5QcL0diU=; b=owGbwMvMwCU28Zj0gdSKO4sYT6slMaQo3mf857bx57Q5Hq8DfDZp8R1W+Ny4gD9sBmt0cor7Odb7 e2pcO0pZGMS4GGTFFFkc2k3C5ZbzVGw2ytSAmcPKBDKEgYtTACaS1sbwP71L+INEhnNUpHZSoX5yt8 N754og1n8iJyqVxP+WKL9kYvinsvVwyoNzyVNUrhxat39l0d4fXPs/xas2l+SGsc890PGAHQA= X-Developer-Key: i=brauner@kernel.org; a=openpgp; fpr=4880B8C9BD0E5106FC070F4F7B3C391EFEA93624 Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org We generally try to avoid installing a file descriptor into the caller's file descriptor table just to close it again via close_fd() in case an error occurs. Instead we reserve a file descriptor but don't install it into the caller's file descriptor table yet. If we fail for other, unrelated reasons we can just close the reserved file descriptor and if we make it past all meaningful error paths we just install it. Fanotify gets this right already for one fd type but not for pidfds. Use the new pidfd_prepare() helper to reserve a pidfd and a pidfd file and switch to the more common fd allocation and installation pattern. Signed-off-by: Christian Brauner --- fs/notify/fanotify/fanotify_user.c | 13 +++++++++---- 1 file changed, 9 insertions(+), 4 deletions(-) diff --git a/fs/notify/fanotify/fanotify_user.c b/fs/notify/fanotify/fanotify_user.c index 8f430bfad487..22fb1cf7e1fc 100644 --- a/fs/notify/fanotify/fanotify_user.c +++ b/fs/notify/fanotify/fanotify_user.c @@ -663,7 +663,7 @@ static ssize_t copy_event_to_user(struct fsnotify_group *group, struct fanotify_info *info = fanotify_event_info(event); unsigned int info_mode = FAN_GROUP_FLAG(group, FANOTIFY_INFO_MODES); unsigned int pidfd_mode = info_mode & FAN_REPORT_PIDFD; - struct file *f = NULL; + struct file *f = NULL, *pidfd_file = NULL; int ret, pidfd = FAN_NOPIDFD, fd = FAN_NOFD; pr_debug("%s: group=%p event=%p\n", __func__, group, event); @@ -718,7 +718,7 @@ static ssize_t copy_event_to_user(struct fsnotify_group *group, !pid_has_task(event->pid, PIDTYPE_TGID)) { pidfd = FAN_NOPIDFD; } else { - pidfd = pidfd_create(event->pid, 0); + pidfd = pidfd_prepare(event->pid, 0, &pidfd_file); if (pidfd < 0) pidfd = FAN_EPIDFD; } @@ -751,6 +751,9 @@ static ssize_t copy_event_to_user(struct fsnotify_group *group, if (f) fd_install(fd, f); + if (pidfd_file) + fd_install(pidfd, pidfd_file); + return metadata.event_len; out_close_fd: @@ -759,8 +762,10 @@ static ssize_t copy_event_to_user(struct fsnotify_group *group, fput(f); } - if (pidfd >= 0) - close_fd(pidfd); + if (pidfd >= 0) { + put_unused_fd(pidfd); + fput(pidfd_file); + } return ret; } -- 2.34.1