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=-2.8 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS,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 DE119C433F5 for ; Fri, 31 Aug 2018 01:54:24 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 988C12083E for ; Fri, 31 Aug 2018 01:54:24 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="cHIUDDO7" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 988C12083E Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=gmail.com 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 S1727555AbeHaF7X (ORCPT ); Fri, 31 Aug 2018 01:59:23 -0400 Received: from mail-yb1-f193.google.com ([209.85.219.193]:44345 "EHLO mail-yb1-f193.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727352AbeHaF7W (ORCPT ); Fri, 31 Aug 2018 01:59:22 -0400 Received: by mail-yb1-f193.google.com with SMTP id l16-v6so330501ybk.11; Thu, 30 Aug 2018 18:54:20 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=from:to:cc:subject:date:message-id:in-reply-to:references; bh=V/nPLJiLoMbwxwUN+SeDjrPjMrJFtIi3YKNpVCr/rfI=; b=cHIUDDO7zpJyjduUj1AwohQqhchaeZcF5rHzrvC830EPVE0vyg+4cTpVyh4a4QtOpU +G9wWJT7qq6cToApALaQAi5T6bf1NbGO24PCuieqXgOz2/YsonS49UPFUl1UdubPctmx F7rY9id1fp/KHKAJ8Tz8JTc+66obEHPfA0q+C6PiT0/7FlWtnXEtToIU4PCwJSkb4CLT JUd+dM0bMrpjsOxGVs3MmiX9hfP6yeltlF/Vs+//MI2Onv+Ly3QKp2V5Fy5v8ul5qVPM q4L4s3/h27gsLS0zx4y2ev2/+80AIbpNemaARAo3pBIWbTfe7+ABErERcJYDvMngGfrv ALOw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references; bh=V/nPLJiLoMbwxwUN+SeDjrPjMrJFtIi3YKNpVCr/rfI=; b=NiXroOqKkgMAbd0Wofn3BkGOQ0977VwIhJ6BLqXsbziVObMc1hm10zZZ12SqRofn5/ 6wHwQn6KBeg1vKmAGa09H+vDIN3xZgaQ7Wa6TdRnVIRp8rzpBdYId/DY+kIUs9nui2Ta iIXP2mYmscyZIMu2ek+wMoaWwXGkeh4d6L/D1Eb68/u+YLkDhSYlquf/BB6k8EVT9jFN cIHA0wajs+8RXtcoYpi9XjhQVWI4up3T9aMniV64SrahO/kccPF93c4B+9f5I2EVx2u6 flSN2+OB1u6/pOSo+P/vshB76qMTJKc23pxql78HsWSz5oGtEQLvu+Z1rSYE5yZUne8V 9HSQ== X-Gm-Message-State: APzg51BQ3l3PNBctQglkFxhVJa4wJmgiLXCUDy/ipVvedhKZ8MTGXnXU GEx9jRolQ2x/EqdL5VKHuyg= X-Google-Smtp-Source: ANB0Vda3dIa2nQlBs/oG8+sRC7aaZ2qqZNVrEidS0io+tqU3QGrL33K0QKG7fhBse0uwNvmKB+eqDw== X-Received: by 2002:a25:23c3:: with SMTP id j186-v6mr832463ybj.259.1535680459994; Thu, 30 Aug 2018 18:54:19 -0700 (PDT) Received: from dennisz-mbp.thefacebook.com ([199.201.65.129]) by smtp.gmail.com with ESMTPSA id j70-v6sm3274084ywb.69.2018.08.30.18.54.19 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 30 Aug 2018 18:54:19 -0700 (PDT) From: Dennis Zhou To: Jens Axboe , Tejun Heo , Johannes Weiner , Josef Bacik Cc: kernel-team@fb.com, linux-block@vger.kernel.org, cgroups@vger.kernel.org, linux-kernel@vger.kernel.org, "Dennis Zhou (Facebook)" Subject: [PATCH 05/15] blkcg: update blkg_lookup_create to do locking Date: Thu, 30 Aug 2018 21:53:46 -0400 Message-Id: <20180831015356.69796-6-dennisszhou@gmail.com> X-Mailer: git-send-email 2.13.5 In-Reply-To: <20180831015356.69796-1-dennisszhou@gmail.com> References: <20180831015356.69796-1-dennisszhou@gmail.com> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: "Dennis Zhou (Facebook)" To know when to create a blkg, the general pattern is to do a blkg_lookup and if that fails, lock and then do a lookup again and if that fails finally create. It doesn't make much sense for everyone who wants to do creation to write this themselves. This changes blkg_lookup_create to do locking and implement this pattern. The old blkg_lookup_create is renamed to __blkg_lookup_create. If a call site wants to do its own error handling or already owns the queue lock, they can use __blkg_lookup_create. Signed-off-by: Dennis Zhou --- block/blk-cgroup.c | 31 ++++++++++++++++++++++++++++--- block/blk-iolatency.c | 2 +- include/linux/blk-cgroup.h | 4 +++- 3 files changed, 32 insertions(+), 5 deletions(-) diff --git a/block/blk-cgroup.c b/block/blk-cgroup.c index d7114308a480..f678cd555814 100644 --- a/block/blk-cgroup.c +++ b/block/blk-cgroup.c @@ -259,7 +259,7 @@ static struct blkcg_gq *blkg_create(struct blkcg *blkcg, } /** - * blkg_lookup_create - lookup blkg, try to create one if not there + * __blkg_lookup_create - lookup blkg, try to create one if not there * @blkcg: blkcg of interest * @q: request_queue of interest * @@ -272,8 +272,8 @@ static struct blkcg_gq *blkg_create(struct blkcg *blkcg, * value on error. If @q is dead, returns ERR_PTR(-EINVAL). If @q is not * dead and bypassing, returns ERR_PTR(-EBUSY). */ -struct blkcg_gq *blkg_lookup_create(struct blkcg *blkcg, - struct request_queue *q) +struct blkcg_gq *__blkg_lookup_create(struct blkcg *blkcg, + struct request_queue *q) { struct blkcg_gq *blkg; @@ -310,6 +310,31 @@ struct blkcg_gq *blkg_lookup_create(struct blkcg *blkcg, } } +/** + * blkg_lookup_create - find or create a blkg + * @blkcg: target block cgroup + * @q: target request_queue + * + * This looks up or creates the blkg representing the unique pair + * of the blkcg and the request_queue. + */ +struct blkcg_gq *blkg_lookup_create(struct blkcg *blkcg, + struct request_queue *q) +{ + struct blkcg_gq *blkg = blkg_lookup(blkcg, q); + unsigned long flags; + + if (unlikely(!blkg)) { + spin_lock_irqsave(q->queue_lock, flags); + + blkg = __blkg_lookup_create(blkcg, q); + + spin_unlock_irqrestore(q->queue_lock, flags); + } + + return blkg; +} + static void blkg_destroy(struct blkcg_gq *blkg) { struct blkcg *blkcg = blkg->blkcg; diff --git a/block/blk-iolatency.c b/block/blk-iolatency.c index 62fdd9002c29..22b2ff0440cc 100644 --- a/block/blk-iolatency.c +++ b/block/blk-iolatency.c @@ -410,7 +410,7 @@ static void blkcg_iolatency_throttle(struct rq_qos *rqos, struct bio *bio, if (unlikely(!blkg)) { if (!lock) spin_lock_irq(q->queue_lock); - blkg = blkg_lookup_create(blkcg, q); + blkg = __blkg_lookup_create(blkcg, q); if (IS_ERR(blkg)) blkg = NULL; if (!lock) diff --git a/include/linux/blk-cgroup.h b/include/linux/blk-cgroup.h index d3cafb1eda48..ea2dd6e6baf2 100644 --- a/include/linux/blk-cgroup.h +++ b/include/linux/blk-cgroup.h @@ -184,6 +184,8 @@ extern struct cgroup_subsys_state * const blkcg_root_css; struct blkcg_gq *blkg_lookup_slowpath(struct blkcg *blkcg, struct request_queue *q, bool update_hint); +struct blkcg_gq *__blkg_lookup_create(struct blkcg *blkcg, + struct request_queue *q); struct blkcg_gq *blkg_lookup_create(struct blkcg *blkcg, struct request_queue *q); int blkcg_init_queue(struct request_queue *q); @@ -835,7 +837,7 @@ static inline bool blkcg_bio_issue_check(struct request_queue *q, blkg = blkg_lookup(blkcg, q); if (unlikely(!blkg)) { spin_lock_irq(q->queue_lock); - blkg = blkg_lookup_create(blkcg, q); + blkg = __blkg_lookup_create(blkcg, q); if (IS_ERR(blkg)) blkg = NULL; spin_unlock_irq(q->queue_lock); -- 2.17.1