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 6606DC5479D for ; Mon, 2 Jan 2023 11:29:57 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236116AbjABL34 (ORCPT ); Mon, 2 Jan 2023 06:29:56 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:50352 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236121AbjABL3Z (ORCPT ); Mon, 2 Jan 2023 06:29:25 -0500 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id BFAFE65A1 for ; Mon, 2 Jan 2023 03:28:53 -0800 (PST) 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 dfw.source.kernel.org (Postfix) with ESMTPS id 4178960E83 for ; Mon, 2 Jan 2023 11:28:53 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 5A7B6C433EF; Mon, 2 Jan 2023 11:28:52 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1672658932; bh=GIolATIKk840jQEdXy1XAO1iPCjtDBumvx+yGs4YaP0=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=GdiE2uUd1vBfmNaMEmmKgmR47ANR7xK7vg3ixcBiS22qTjeRRAIGJ9VA1S9JhABRm vYJQE0ecjVUhAXFBRg578L3eHREuMH8xjVgftzof1BI0PUcv/1o5REKMqIHzwrjWGS JPIbEiPcm0tJfunN/jTp99JGmusSn+4NsttzraHk= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Jens Axboe Subject: [PATCH 6.0 54/74] eventfd: provide a eventfd_signal_mask() helper Date: Mon, 2 Jan 2023 12:22:27 +0100 Message-Id: <20230102110554.407060232@linuxfoundation.org> X-Mailer: git-send-email 2.39.0 In-Reply-To: <20230102110552.061937047@linuxfoundation.org> References: <20230102110552.061937047@linuxfoundation.org> User-Agent: quilt/0.67 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Jens Axboe commit 03e02acda8e267a8183e1e0ed289ff1ef9cd7ed8 upstream. This is identical to eventfd_signal(), but it allows the caller to pass in a mask to be used for the poll wakeup key. The use case is avoiding repeated multishot triggers if we have a dependency between eventfd and io_uring. If we setup an eventfd context and register that as the io_uring eventfd, and at the same time queue a multishot poll request for the eventfd context, then any CQE posted will repeatedly trigger the multishot request until it terminates when the CQ ring overflows. In preparation for io_uring detecting this circular dependency, add the mentioned helper so that io_uring can pass in EPOLL_URING as part of the poll wakeup key. Cc: stable@vger.kernel.org # 6.0 [axboe: fold in !CONFIG_EVENTFD fix from Zhang Qilong] Signed-off-by: Jens Axboe Signed-off-by: Greg Kroah-Hartman --- fs/eventfd.c | 37 +++++++++++++++++++++---------------- include/linux/eventfd.h | 7 +++++++ 2 files changed, 28 insertions(+), 16 deletions(-) diff --git a/fs/eventfd.c b/fs/eventfd.c index c0ffee99ad23..249ca6c0b784 100644 --- a/fs/eventfd.c +++ b/fs/eventfd.c @@ -43,21 +43,7 @@ struct eventfd_ctx { int id; }; -/** - * eventfd_signal - Adds @n to the eventfd counter. - * @ctx: [in] Pointer to the eventfd context. - * @n: [in] Value of the counter to be added to the eventfd internal counter. - * The value cannot be negative. - * - * This function is supposed to be called by the kernel in paths that do not - * allow sleeping. In this function we allow the counter to reach the ULLONG_MAX - * value, and we signal this as overflow condition by returning a EPOLLERR - * to poll(2). - * - * Returns the amount by which the counter was incremented. This will be less - * than @n if the counter has overflowed. - */ -__u64 eventfd_signal(struct eventfd_ctx *ctx, __u64 n) +__u64 eventfd_signal_mask(struct eventfd_ctx *ctx, __u64 n, unsigned mask) { unsigned long flags; @@ -78,12 +64,31 @@ __u64 eventfd_signal(struct eventfd_ctx *ctx, __u64 n) n = ULLONG_MAX - ctx->count; ctx->count += n; if (waitqueue_active(&ctx->wqh)) - wake_up_locked_poll(&ctx->wqh, EPOLLIN); + wake_up_locked_poll(&ctx->wqh, EPOLLIN | mask); current->in_eventfd = 0; spin_unlock_irqrestore(&ctx->wqh.lock, flags); return n; } + +/** + * eventfd_signal - Adds @n to the eventfd counter. + * @ctx: [in] Pointer to the eventfd context. + * @n: [in] Value of the counter to be added to the eventfd internal counter. + * The value cannot be negative. + * + * This function is supposed to be called by the kernel in paths that do not + * allow sleeping. In this function we allow the counter to reach the ULLONG_MAX + * value, and we signal this as overflow condition by returning a EPOLLERR + * to poll(2). + * + * Returns the amount by which the counter was incremented. This will be less + * than @n if the counter has overflowed. + */ +__u64 eventfd_signal(struct eventfd_ctx *ctx, __u64 n) +{ + return eventfd_signal_mask(ctx, n, 0); +} EXPORT_SYMBOL_GPL(eventfd_signal); static void eventfd_free_ctx(struct eventfd_ctx *ctx) diff --git a/include/linux/eventfd.h b/include/linux/eventfd.h index 30eb30d6909b..786824f58d3d 100644 --- a/include/linux/eventfd.h +++ b/include/linux/eventfd.h @@ -40,6 +40,7 @@ struct file *eventfd_fget(int fd); struct eventfd_ctx *eventfd_ctx_fdget(int fd); struct eventfd_ctx *eventfd_ctx_fileget(struct file *file); __u64 eventfd_signal(struct eventfd_ctx *ctx, __u64 n); +__u64 eventfd_signal_mask(struct eventfd_ctx *ctx, __u64 n, unsigned mask); int eventfd_ctx_remove_wait_queue(struct eventfd_ctx *ctx, wait_queue_entry_t *wait, __u64 *cnt); void eventfd_ctx_do_read(struct eventfd_ctx *ctx, __u64 *cnt); @@ -66,6 +67,12 @@ static inline int eventfd_signal(struct eventfd_ctx *ctx, int n) return -ENOSYS; } +static inline int eventfd_signal_mask(struct eventfd_ctx *ctx, __u64 n, + unsigned mask) +{ + return -ENOSYS; +} + static inline void eventfd_ctx_put(struct eventfd_ctx *ctx) { -- 2.39.0