From patchwork Fri May 1 17:53:57 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jens Axboe X-Patchwork-Id: 11523103 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 5D605912 for ; Fri, 1 May 2020 17:54:00 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 4445820857 for ; Fri, 1 May 2020 17:54:00 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=kernel-dk.20150623.gappssmtp.com header.i=@kernel-dk.20150623.gappssmtp.com header.b="Ko8kSvtM" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729694AbgEARx7 (ORCPT ); Fri, 1 May 2020 13:53:59 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:35856 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-FAIL-OK-FAIL) by vger.kernel.org with ESMTP id S1729291AbgEARx7 (ORCPT ); Fri, 1 May 2020 13:53:59 -0400 Received: from mail-il1-x143.google.com (mail-il1-x143.google.com [IPv6:2607:f8b0:4864:20::143]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 2CE65C061A0C for ; Fri, 1 May 2020 10:53:59 -0700 (PDT) Received: by mail-il1-x143.google.com with SMTP id u189so5171212ilc.4 for ; Fri, 01 May 2020 10:53:59 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel-dk.20150623.gappssmtp.com; s=20150623; h=from:subject:to:cc:message-id:date:user-agent:mime-version :content-language:content-transfer-encoding; bh=dNu8cTkVAel6kkIGd2Z1GoaI4LYxnwwQdrPVYtjvHuw=; b=Ko8kSvtMTznmK4Pf/hYlBVtXpXbakAslYsizbJWGK6s9mR+8XttduJDjCpzEuhiZkK Eaa6sEKnLEMT8WnLO/zYng0Cn/lyszxih7Hi3OvU/kaMp5isJXjd/UNhj4GI980hRNYm GwbWdwXet0IrfXdQBDs2EznAzJw5yIgBKUjgo2aIICzbYqU9/t6OEuHoTrGUuj9CZ/N/ MzGu4UbfL8ahyEum8KspIt3Bb7LKUn6TYm/27wKU7JY2AtvoVKScLE1BW4cXECsw+dgJ yNODVmAL8cPoae2PlQpjkM5A8/V7EgWgfkvKrXx359Dq9tTZlYJPUz1baUDPiv5Op+XI wJ1Q== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:subject:to:cc:message-id:date:user-agent :mime-version:content-language:content-transfer-encoding; bh=dNu8cTkVAel6kkIGd2Z1GoaI4LYxnwwQdrPVYtjvHuw=; b=BL1cl1z0Pe/A9YEfS5D9uJ9xFKZ5DifYCPQdRo4hboXFVdHT9cjk3osihgvivQ9jVk TjIoFuWeQCgGfBFuK7U5AJK/kPEksyR8KxNa3Si7QvkZ28snwCELQL1FvAib0EQq6SQG Fejnzt/D47KKqbEhM18j9bKTNrp6Sr/Y2syQ9meG9f8HS0xIOHW4cvHa1nXOP3B7yi5o BPkib9BdXUspNOHhrCV/2xV4f4UV5GBmVOJf/EUuBrGpi7JwQUIl/fi+vSuh5T5xaNIK +O1A6WboYuGP84+Qnpxl420Qwr26SADqpHFvT2nQ9F6ksc5jBwHg8wK0JHGKBhIv6C87 bTWA== X-Gm-Message-State: AGi0PuYFysxS3NTSJwVTHX0c/Pi3A3usrG79DtynJ1v6pwdbbqmxUev0 sebrD+clAQummuw1d62FGUS1Lg== X-Google-Smtp-Source: APiQypKOBb5wGUM5qyn893wxbiA3WMRiRsUfPWjKE3lKl98+s0INI+P8z8hyG+flyiXESNHGrgJpWA== X-Received: by 2002:a92:aa0f:: with SMTP id j15mr4792191ili.211.1588355638429; Fri, 01 May 2020 10:53:58 -0700 (PDT) Received: from [192.168.1.159] ([65.144.74.34]) by smtp.gmail.com with ESMTPSA id 140sm1506810ilc.44.2020.05.01.10.53.57 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 01 May 2020 10:53:57 -0700 (PDT) From: Jens Axboe Subject: [PATCH v3v] eventfd: convert to f_op->read_iter() To: Alexander Viro Cc: linux-fsdevel , "linux-kernel@vger.kernel.org" Message-ID: <7e9c4447-d7b4-2753-ad28-a668e3ce370a@kernel.dk> Date: Fri, 1 May 2020 11:53:57 -0600 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.7.0 MIME-Version: 1.0 Content-Language: en-US Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org eventfd is using ->read() as it's file_operations read handler, but this prevents passing in information about whether a given IO operation is blocking or not. We can only use the file flags for that. To support async (-EAGAIN/poll based) retries for io_uring, we need ->read_iter() support. Convert eventfd to using ->read_iter(). Signed-off-by: Jens Axboe --- Actually send out the right patch... Since v2: - Cleanup eventfd_read() as per Al's suggestions Since v1: - Add FMODE_NOWAIT to the eventfd file diff --git a/fs/eventfd.c b/fs/eventfd.c index 78e41c7c3d05..c9fa1e9cf5e3 100644 --- a/fs/eventfd.c +++ b/fs/eventfd.c @@ -216,32 +216,32 @@ int eventfd_ctx_remove_wait_queue(struct eventfd_ctx *ctx, wait_queue_entry_t *w } EXPORT_SYMBOL_GPL(eventfd_ctx_remove_wait_queue); -static ssize_t eventfd_read(struct file *file, char __user *buf, size_t count, - loff_t *ppos) +static ssize_t eventfd_read(struct kiocb *iocb, struct iov_iter *to) { + struct file *file = iocb->ki_filp; struct eventfd_ctx *ctx = file->private_data; - ssize_t res; __u64 ucnt = 0; DECLARE_WAITQUEUE(wait, current); - if (count < sizeof(ucnt)) + if (iov_iter_count(to) < sizeof(ucnt)) return -EINVAL; - spin_lock_irq(&ctx->wqh.lock); - res = -EAGAIN; - if (ctx->count > 0) - res = sizeof(ucnt); - else if (!(file->f_flags & O_NONBLOCK)) { + if (!ctx->count) { + if ((file->f_flags & O_NONBLOCK) || + (iocb->ki_flags & IOCB_NOWAIT)) { + spin_unlock_irq(&ctx->wqh.lock); + return -EAGAIN; + } __add_wait_queue(&ctx->wqh, &wait); for (;;) { set_current_state(TASK_INTERRUPTIBLE); - if (ctx->count > 0) { - res = sizeof(ucnt); + if (ctx->count) break; - } if (signal_pending(current)) { - res = -ERESTARTSYS; - break; + __remove_wait_queue(&ctx->wqh, &wait); + __set_current_state(TASK_RUNNING); + spin_unlock_irq(&ctx->wqh.lock); + return -ERESTARTSYS; } spin_unlock_irq(&ctx->wqh.lock); schedule(); @@ -250,17 +250,14 @@ static ssize_t eventfd_read(struct file *file, char __user *buf, size_t count, __remove_wait_queue(&ctx->wqh, &wait); __set_current_state(TASK_RUNNING); } - if (likely(res > 0)) { - eventfd_ctx_do_read(ctx, &ucnt); - if (waitqueue_active(&ctx->wqh)) - wake_up_locked_poll(&ctx->wqh, EPOLLOUT); - } + eventfd_ctx_do_read(ctx, &ucnt); + if (waitqueue_active(&ctx->wqh)) + wake_up_locked_poll(&ctx->wqh, EPOLLOUT); spin_unlock_irq(&ctx->wqh.lock); - - if (res > 0 && put_user(ucnt, (__u64 __user *)buf)) + if (unlikely(copy_to_iter(&ucnt, sizeof(ucnt), to) != sizeof(ucnt))) return -EFAULT; - return res; + return sizeof(ucnt); } static ssize_t eventfd_write(struct file *file, const char __user *buf, size_t count, @@ -329,7 +326,7 @@ static const struct file_operations eventfd_fops = { #endif .release = eventfd_release, .poll = eventfd_poll, - .read = eventfd_read, + .read_iter = eventfd_read, .write = eventfd_write, .llseek = noop_llseek, }; @@ -427,8 +424,17 @@ static int do_eventfd(unsigned int count, int flags) fd = anon_inode_getfd("[eventfd]", &eventfd_fops, ctx, O_RDWR | (flags & EFD_SHARED_FCNTL_FLAGS)); - if (fd < 0) + if (fd < 0) { eventfd_free_ctx(ctx); + } else { + struct file *file; + + file = fget(fd); + if (file) { + file->f_mode |= FMODE_NOWAIT; + fput(file); + } + } return fd; }