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 A9E86C433F5 for ; Tue, 19 Oct 2021 15:49:56 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 8A8F0610CC for ; Tue, 19 Oct 2021 15:49:56 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232631AbhJSPwI (ORCPT ); Tue, 19 Oct 2021 11:52:08 -0400 Received: from mail.kernel.org ([198.145.29.99]:32934 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229803AbhJSPwH (ORCPT ); Tue, 19 Oct 2021 11:52:07 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id AA28D610CC; Tue, 19 Oct 2021 15:49:53 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1634658594; bh=//aSf488iOwsBGJ5XsBtanerGR/joEI23orGPxMdgRg=; h=From:To:Cc:Subject:Date:In-Reply-To:From; b=ZDPgsdC28OzFPax++9DOanfuZUyMbIh6wmAXTUhc7HWmMRv+FR6ywCquvL0V7umpX ccShfRvZ8sg0MEsMiOZqpz3EGkcBcxfcS2JWuZ1W/aFxnRM9W6nZkgT4bmtMsfTTHu u/BLZLqF5MOswUEPUW2iyLofZRauP4Am+QL0ptLhjhYrmxsfOrVbt1E2RIaEAE2FwY M42/ojtzgcIe0cUBgI5O95U0Fi+EEL1b28rCuFOOhyLhrK3knuPgNpwbO6L6twKLr8 efVwalsoEy4DkBObQcRnwTZsKwt9E50OEEk5gBst9pwbb+YnrLwqIJKabmXa1eO/lI YJTq/rAnYVCgw== From: SeongJae Park To: SeongJae Park Cc: Xin Hao , 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 15:49:51 +0000 Message-Id: <20211019154951.17570-1-sj@kernel.org> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20211019154243.17474-1-sj@kernel.org> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 19 Oct 2021 15:42:43 +0000 SeongJae Park wrote: > 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? Also, I think 'damon_targets_empty()' (s/target/targets/) might be a better naming? Thanks, SJ > > > 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