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 mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 5E9F6C433EF for ; Tue, 19 Oct 2021 15:42:50 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 006646113D for ; Tue, 19 Oct 2021 15:42:49 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org 006646113D Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=kvack.org Received: by kanga.kvack.org (Postfix) id 449976B009B; Tue, 19 Oct 2021 11:42:49 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 3D2D56B009C; Tue, 19 Oct 2021 11:42:49 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 299CD6B009D; Tue, 19 Oct 2021 11:42:49 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0047.hostedemail.com [216.40.44.47]) by kanga.kvack.org (Postfix) with ESMTP id 15E8E6B009B for ; Tue, 19 Oct 2021 11:42:49 -0400 (EDT) Received: from smtpin30.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay03.hostedemail.com (Postfix) with ESMTP id BE0848249980 for ; Tue, 19 Oct 2021 15:42:48 +0000 (UTC) X-FDA: 78713604816.30.7B9077D Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by imf17.hostedemail.com (Postfix) with ESMTP id 4F536F000392 for ; Tue, 19 Oct 2021 15:42:48 +0000 (UTC) Received: by mail.kernel.org (Postfix) with ESMTPSA id E14C660FC1; Tue, 19 Oct 2021 15:42:46 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1634658167; bh=GxTywgB7gag26Qwpgply5teQtnEx/fUwBCWcWsCIZUY=; h=From:To:Cc:Subject:Date:In-Reply-To:From; b=p0tOZ5OHaxxFNW0GtZko8L1iksdjpwMN1UzeBr/iDrhOerywVurXBOdFqqX3RdiPA ZJZwV1pow3v7tiG18ckeV0vgjnQMgAE3toWZDPasG4Drf8XM6es8n47bNZUzmWhSG6 VMXCS8KMsEiHUCEca0re/X6/Zf5kIPRPTAYr1QcYmYSo/bsYNRGF896ua+F2RkLQB0 W7v7H/7XHwzm1pDKRlaTvKWGa0t0TxgVpwORLBlhSDIspT0b5rLDIkltx39EuFxOYR IEvYZ0VxHzZSrTelJBDPPRrFyr4Mkb7O6nOLAx6/ZFmwFsif4YgHAOdX7PZFvWoGxZ bQUBbQ8/pPWpA== From: SeongJae Park To: Xin Hao Cc: sjpark@amazon.de, akpm@linux-foundation.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v2 2/2] mm/damon/dbgfs: Add adaptive_targets list check before enable monitor_on Date: Tue, 19 Oct 2021 15:42:43 +0000 Message-Id: <20211019154243.17474-1-sj@kernel.org> X-Mailer: git-send-email 2.17.1 In-Reply-To: X-Rspamd-Queue-Id: 4F536F000392 Authentication-Results: imf17.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=p0tOZ5OH; spf=pass (imf17.hostedemail.com: domain of sj@kernel.org designates 198.145.29.99 as permitted sender) smtp.mailfrom=sj@kernel.org; dmarc=pass (policy=none) header.from=kernel.org X-Stat-Signature: wfhxpmfuzfa51r788ncz4htbo8mncafi X-Rspamd-Server: rspam05 X-HE-Tag: 1634658168-492495 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: Hello Xin, On Tue, 19 Oct 2021 22:26:04 +0800 Xin Hao wrote: > When the ctx->adaptive_targets list is empty, > i did some test on monitor_on interface like this. s/i/I/ > > echo on > /sys/kernel/debug/damon/monitor_on > [ 851.988307] damon: kdamond (5390) starts Could you please add four spaces in the beginning of this example terminal outputs? Also, I think confirming targets are empty like below before writing 'on' could make this example better. # cat /sys/kernel/debug/damon/target_ids # or, like below. # echo > /sys/kernel/debug/damon/target_ids > > Though the ctx->adaptive_targets list is empty, but the > kthread_run still be called, and the kdamond.x thread still > be created, this is meaningless. > > So there adds a judgment in 'dbgfs_monitor_on_write', > if the ctx->adaptive_targets list is empty, return -EINVAL. > > Signed-off-by: Xin Hao > --- > include/linux/damon.h | 1 + > mm/damon/core.c | 5 +++++ > mm/damon/dbgfs.c | 10 ++++++++-- > 3 files changed, 14 insertions(+), 2 deletions(-) > > diff --git a/include/linux/damon.h b/include/linux/damon.h > index 715dadd21f7c..06acf73fe9db 100644 > --- a/include/linux/damon.h > +++ b/include/linux/damon.h > @@ -316,6 +316,7 @@ void damon_destroy_scheme(struct damos *s); > > struct damon_target *damon_new_target(unsigned long id); > void damon_add_target(struct damon_ctx *ctx, struct damon_target *t); > +int damon_target_empty(struct damon_ctx *ctx); Seems 'bool' would be better for the return type? > void damon_free_target(struct damon_target *t); > void damon_destroy_target(struct damon_target *t); > unsigned int damon_nr_regions(struct damon_target *t); > diff --git a/mm/damon/core.c b/mm/damon/core.c > index 2f6785737902..c651b49249e5 100644 > --- a/mm/damon/core.c > +++ b/mm/damon/core.c > @@ -156,6 +156,11 @@ void damon_add_target(struct damon_ctx *ctx, struct damon_target *t) > list_add_tail(&t->list, &ctx->adaptive_targets); > } > > +int damon_target_empty(struct damon_ctx *ctx) > +{ > + return list_empty(&ctx->adaptive_targets); > +} > + > static void damon_del_target(struct damon_target *t) > { > list_del(&t->list); > diff --git a/mm/damon/dbgfs.c b/mm/damon/dbgfs.c > index 38188347d8ab..bac42dd358d1 100644 > --- a/mm/damon/dbgfs.c > +++ b/mm/damon/dbgfs.c > @@ -865,9 +865,15 @@ static ssize_t dbgfs_monitor_on_write(struct file *file, > return -EINVAL; > } > > - if (!strncmp(kbuf, "on", count)) > + if (!strncmp(kbuf, "on", count)) { > + int i; > + > + for (i = 0; i < dbgfs_nr_ctxs; i++) { > + if (damon_target_empty(dbgfs_ctxs[i])) > + return -EINVAL; > + } > err = damon_start(dbgfs_ctxs, dbgfs_nr_ctxs); > - else if (!strncmp(kbuf, "off", count)) > + } else if (!strncmp(kbuf, "off", count)) > err = damon_stop(dbgfs_ctxs, dbgfs_nr_ctxs); > else > err = -EINVAL; Please use braces for all above branches: https://docs.kernel.org/process/coding-style.html#placing-braces-and-spaces Thanks, SJ > -- > 2.31.0