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 X-Spam-Level: X-Spam-Status: No, score=-2.9 required=3.0 tests=DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS,T_DKIM_INVALID, URIBL_BLOCKED,USER_AGENT_GIT 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 7B991C46461 for ; Mon, 30 Jul 2018 07:16:03 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 2D5D120893 for ; Mon, 30 Jul 2018 07:16:03 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="aGpfAAmj" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 2D5D120893 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=lst.de Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726790AbeG3Itg (ORCPT ); Mon, 30 Jul 2018 04:49:36 -0400 Received: from bombadil.infradead.org ([198.137.202.133]:33100 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726366AbeG3Itf (ORCPT ); Mon, 30 Jul 2018 04:49:35 -0400 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20170209; h=References:In-Reply-To:Message-Id: Date:Subject:Cc:To:From:Sender:Reply-To:MIME-Version:Content-Type: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=BWtMZ2W9plgEcpyRGLCAFtPZ5rLA8SWc74nPm8axhjY=; b=aGpfAAmjxP0hHWIscuewssazE LfVx4vMt9vWqYkraB0Ls5OkC7ArV4DE5dpy+0dHUMtIQ4mqJ8/Gr5obj8JO79DTVDACvzQ7Z1Gwlx +SmstgRijILTFKQAdTvSEJeVeiCwdBkPgGdjbnuggyQcuP+jL3wTEHTmMt19BHLdzx+DbOQ3+lNhi bPOYY1nCjwpaB9u99HSZxkxMgNHny95+JNNjQvuWrMFe0Qby6gtg9UjWd1lzAW3tFM4btZ9HujpgW ODfpnxHAxXafoE4aZ55l1Vxs1SyIlqO8EQ5q4g4P4tjNuhRIqgfiT8flE9EJIziGzzvKXpfjGmk34 V/rzmPmsQ==; Received: from 089144213232.atnat0022.highway.a1.net ([89.144.213.232] helo=localhost) by bombadil.infradead.org with esmtpsa (Exim 4.90_1 #2 (Red Hat Linux)) id 1fk2PP-0000Dn-57; Mon, 30 Jul 2018 07:15:59 +0000 From: Christoph Hellwig To: viro@zeniv.linux.org.uk Cc: Avi Kivity , linux-aio@kvack.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH 2/4] aio: add a iocb refcount Date: Mon, 30 Jul 2018 09:15:42 +0200 Message-Id: <20180730071544.23998-3-hch@lst.de> X-Mailer: git-send-email 2.18.0 In-Reply-To: <20180730071544.23998-1-hch@lst.de> References: <20180730071544.23998-1-hch@lst.de> X-SRS-Rewrite: SMTP reverse-path rewritten from by bombadil.infradead.org. See http://www.infradead.org/rpr.html Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org This is needed to prevent races caused by the way the ->poll API works. To avoid introducing overhead for other users of the iocbs we initialize it to zero and only do refcount operations if it is non-zero in the completion path. Signed-off-by: Christoph Hellwig --- fs/aio.c | 17 +++++++++++++---- 1 file changed, 13 insertions(+), 4 deletions(-) diff --git a/fs/aio.c b/fs/aio.c index 27454594e37a..fe2018ada32c 100644 --- a/fs/aio.c +++ b/fs/aio.c @@ -18,6 +18,7 @@ #include #include #include +#include #include #include @@ -178,6 +179,7 @@ struct aio_kiocb { struct list_head ki_list; /* the aio core uses this * for cancellation */ + refcount_t ki_refcnt; /* * If the aio_resfd field of the userspace iocb is not zero, @@ -1015,6 +1017,7 @@ static inline struct aio_kiocb *aio_get_req(struct kioctx *ctx) percpu_ref_get(&ctx->reqs); INIT_LIST_HEAD(&req->ki_list); + refcount_set(&req->ki_refcnt, 0); req->ki_ctx = ctx; return req; out_put: @@ -1049,6 +1052,15 @@ static struct kioctx *lookup_ioctx(unsigned long ctx_id) return ret; } +static inline void iocb_put(struct aio_kiocb *iocb) +{ + if (refcount_read(&iocb->ki_refcnt) == 0 || + refcount_dec_and_test(&iocb->ki_refcnt)) { + percpu_ref_put(&iocb->ki_ctx->reqs); + kmem_cache_free(kiocb_cachep, iocb); + } +} + /* aio_complete * Called when the io request on the given iocb is complete. */ @@ -1118,8 +1130,6 @@ static void aio_complete(struct aio_kiocb *iocb, long res, long res2) eventfd_ctx_put(iocb->ki_eventfd); } - kmem_cache_free(kiocb_cachep, iocb); - /* * We have to order our ring_info tail store above and test * of the wait list below outside the wait lock. This is @@ -1130,8 +1140,7 @@ static void aio_complete(struct aio_kiocb *iocb, long res, long res2) if (waitqueue_active(&ctx->wait)) wake_up(&ctx->wait); - - percpu_ref_put(&ctx->reqs); + iocb_put(iocb); } /* aio_read_events_ring -- 2.18.0