From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Cyrus-Session-Id: sloti22d1t05-2401354-1526989263-2-11019035270208732895 X-Sieve: CMU Sieve 3.0 X-Spam-known-sender: no X-Spam-score: 0.0 X-Spam-hits: BAYES_00 -1.9, HEADER_FROM_DIFFERENT_DOMAINS 0.248, MAILING_LIST_MULTI -1, RCVD_IN_DNSWL_HI -5, LANGUAGES en, BAYES_USED global, SA_VERSION 3.4.0 X-Spam-source: IP='209.132.180.67', Host='vger.kernel.org', Country='US', FromHeader='de', MailFrom='org' X-Spam-charsets: X-Resolved-to: greg@kroah.com X-Delivered-to: greg@kroah.com X-Mail-from: linux-api-owner@vger.kernel.org ARC-Seal: i=1; a=rsa-sha256; cv=none; d=messagingengine.com; s=fm2; t= 1526989263; b=GjZ3e3UvJslKzsGu4GextGPCkvklOLM5uob7cQjOy307zGeIM3 ygXJuEr5Z+aHrEecypOy9icriZG4k6SkTccKTYl9HBaUc6nDroXM3yND2qio59/P kp41V+PevLIWKK3SbQCUF9/8ovbdnEbk5JQ8FiCOnUr9Vq1gGd5Nkap818qylXUe Crz25zCb0DX0JVMzhEvs18YScworoUFxHdwi1aY1cwnuIJx/wNPpwa0JRAHci8iZ EcbtYiGCoikZo0c2poMsuhZqqhjJ2PYbaqYiX7Q1r0YEn0XohDOe11eRYGuoQRLy c55OLLkBgZIJCs7LZf9/EXxwVmkSYsWnkAJA== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d= messagingengine.com; h=from:to:cc:subject:date:message-id :in-reply-to:references:sender:list-id; s=fm2; t=1526989263; bh= czZ1vQKH3kUTe3dm+q8SlezuUXHOk39hTISwN08Upf8=; b=f/M9xcGXn+LuKQ27 +AZCJMAxPzbiOEcpBew8xuQLwjCXBuKb6E8+8bu3jYScmq/3495QmYVij6azmn0f g0HZunGXntyjORKq4M0pzccCougiSoGvGRwkcsbY8rk7WJHPYVLwVy+K6vtMIs3L rxlf802jrOXKZ4JJmtnjstONNSxz1WOEEw/tq70Qm4WcT/Rf2x/lh94/aURp1g3L 3LWrhTRlIVlLNdq4Qom3J1a8cK0w7UWh/x7dsjie1i1bg3RaQcBM8rQNs796pe5A qm0dfc8wGVlumBR421WB3zbi4ePT1aEqA6xWknveb3Y+IKSckuydVii+i75uE4L3 p7cyEA== ARC-Authentication-Results: i=1; mx2.messagingengine.com; arc=none (no signatures found); dkim=fail (message has been altered, 2048-bit rsa key sha256) header.d=infradead.org header.i=@infradead.org header.b=IY09dpxY x-bits=2048 x-keytype=rsa x-algorithm=sha256 x-selector=bombadil.20170209; dmarc=none (p=none,has-list-id=yes,d=none) header.from=lst.de; iprev=pass policy.iprev=209.132.180.67 (vger.kernel.org); spf=none smtp.mailfrom=linux-api-owner@vger.kernel.org smtp.helo=vger.kernel.org; x-aligned-from=fail; x-cm=none score=0; x-ptr=pass x-ptr-helo=vger.kernel.org x-ptr-lookup=vger.kernel.org; x-return-mx=pass smtp.domain=vger.kernel.org smtp.result=pass smtp_org.domain=kernel.org smtp_org.result=pass smtp_is_org_domain=no header.domain=lst.de header.result=pass header_is_org_domain=yes; x-vs=clean score=0 state=0 Authentication-Results: mx2.messagingengine.com; arc=none (no signatures found); dkim=fail (message has been altered, 2048-bit rsa key sha256) header.d=infradead.org header.i=@infradead.org header.b=IY09dpxY x-bits=2048 x-keytype=rsa x-algorithm=sha256 x-selector=bombadil.20170209; dmarc=none (p=none,has-list-id=yes,d=none) header.from=lst.de; iprev=pass policy.iprev=209.132.180.67 (vger.kernel.org); spf=none smtp.mailfrom=linux-api-owner@vger.kernel.org smtp.helo=vger.kernel.org; x-aligned-from=fail; x-cm=none score=0; x-ptr=pass x-ptr-helo=vger.kernel.org x-ptr-lookup=vger.kernel.org; x-return-mx=pass smtp.domain=vger.kernel.org smtp.result=pass smtp_org.domain=kernel.org smtp_org.result=pass smtp_is_org_domain=no header.domain=lst.de header.result=pass header_is_org_domain=yes; x-vs=clean score=0 state=0 X-ME-VSCategory: clean X-CM-Envelope: MS4wfH6D9eCOoPejOIHF42EDtaPh5LPaxrJf4uuZMaU4iaBykA6ChG7CzkwB+7FZJaZEhAVglgWquHFnvRCePMlDDTnNs6I1xGha8CIVatReLKUcnU/eezfk KlXX84KCZBKjE3JRGGfCNwM58CuAeQy9E+xXWjYUMhQlM3KEiOH/IJb6Mpu6ZatJVPz86kAT1HyL2O4vSoogO1y2SksCw0a+n0EqLs7irWybJJDo4muG6O4c X-CM-Analysis: v=2.3 cv=E8HjW5Vl c=1 sm=1 tr=0 a=UK1r566ZdBxH71SXbqIOeA==:117 a=UK1r566ZdBxH71SXbqIOeA==:17 a=VUJBJC2UJ8kA:10 a=VwQbUJbxAAAA:8 a=xkpDaeRCmLSUBmX8ZpQA:9 a=x8gzFH9gYPwA:10 a=AjGcO6oz07-iQ99wixmX:22 X-ME-CMScore: 0 X-ME-CMCategory: none Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751525AbeEVLkw (ORCPT ); Tue, 22 May 2018 07:40:52 -0400 Received: from bombadil.infradead.org ([198.137.202.133]:36648 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751872AbeEVLb5 (ORCPT ); Tue, 22 May 2018 07:31:57 -0400 From: Christoph Hellwig To: viro@zeniv.linux.org.uk Cc: Avi Kivity , linux-aio@kvack.org, linux-fsdevel@vger.kernel.org, netdev@vger.kernel.org, linux-api@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH 09/31] aio: try to complete poll iocbs without context switch Date: Tue, 22 May 2018 13:30:46 +0200 Message-Id: <20180522113108.25713-10-hch@lst.de> X-Mailer: git-send-email 2.17.0 In-Reply-To: <20180522113108.25713-1-hch@lst.de> References: <20180522113108.25713-1-hch@lst.de> X-SRS-Rewrite: SMTP reverse-path rewritten from by bombadil.infradead.org. See http://www.infradead.org/rpr.html Sender: linux-api-owner@vger.kernel.org X-Mailing-List: linux-api@vger.kernel.org X-getmail-retrieved-from-mailbox: INBOX X-Mailing-List: linux-kernel@vger.kernel.org List-ID: If we can acquire ctx_lock without spinning we can just remove our iocb from the active_reqs list, and thus complete the iocbs from the wakeup context. Signed-off-by: Christoph Hellwig --- fs/aio.c | 20 +++++++++++++++++--- 1 file changed, 17 insertions(+), 3 deletions(-) diff --git a/fs/aio.c b/fs/aio.c index 4d1eabce6659..85d9102431db 100644 --- a/fs/aio.c +++ b/fs/aio.c @@ -1632,6 +1632,7 @@ static int aio_poll_wake(struct wait_queue_entry *wait, unsigned mode, int sync, void *key) { struct poll_iocb *req = container_of(wait, struct poll_iocb, wait); + struct aio_kiocb *iocb = container_of(req, struct aio_kiocb, poll); struct file *file = req->file; __poll_t mask = key_to_poll(key); @@ -1647,9 +1648,22 @@ static int aio_poll_wake(struct wait_queue_entry *wait, unsigned mode, int sync, __aio_poll_remove(req); - req->events = mask; - INIT_WORK(&req->work, aio_poll_work); - schedule_work(&req->work); + /* + * Try completing without a context switch if we can acquire ctx_lock + * without spinning. Otherwise we need to defer to a workqueue to + * avoid a deadlock due to the lock order. + */ + if (spin_trylock(&iocb->ki_ctx->ctx_lock)) { + list_del_init(&iocb->ki_list); + spin_unlock(&iocb->ki_ctx->ctx_lock); + + __aio_poll_complete(req, mask); + } else { + req->events = mask; + INIT_WORK(&req->work, aio_poll_work); + schedule_work(&req->work); + } + return 1; } -- 2.17.0