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[198.0.35.241]) by smtp.gmail.com with ESMTPSA id y4-20020a170902ed4400b001b8943b37a5sm2216722plb.24.2023.08.25.14.32.34 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 25 Aug 2023 14:32:34 -0700 (PDT) Date: Fri, 25 Aug 2023 14:32:34 -0700 From: Kees Cook To: SeongJae Park Cc: Andrew Morton , damon@lists.linux.dev, linux-mm@kvack.org, linux-kernel@vger.kernel.org, Qing Zhao , linux-hardening@vger.kernel.org Subject: Re: [RFC PATCH] mm/damon/sysfs: add __counted_by() annotation Message-ID: <202308251426.94092475C3@keescook> References: <20230825020441.65431-1-sj@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20230825020441.65431-1-sj@kernel.org> X-Stat-Signature: mza91kpm3rqq4xnfawe7egtgeuuczsca X-Rspamd-Server: rspam10 X-Rspamd-Queue-Id: 7922040017 X-Rspam-User: X-HE-Tag: 1692999156-114631 X-HE-Meta: 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 AJBg7Ub+ Hx2/Psg2zfIleyqxr5pOT527YjcHQP8rlaCVBpiX+Q/kDIZwyjR19YwzDx6npviO5+WKiTRkQA4D63gAmW9iQrC8Qy5w3QS9zo4G27I6+DEkQgOQX0EWouuTj1bdHkWJFZlH7DIHhQPvS8HsOlBV7+U9EptTKOG3FioImsh891i0kn1sVXbZqKiMzPouZIc5hqzdf5k0K/E6QrEHY29QYfLVQD37O0eeDrWVx3jcqfTLUmTKSbzpVbTMz+uloASnYqDXW2GaAN3IDimI26j9EJIr7DShzv5aGxeRhsY5uWmkIm6gMQx0A4mQNZobOv4HjNRFvOATh2yhYBovHO46fm2badihl9a7+dBInJ2n8Cmcv11fjkCCA5ENNbIgbw1DYkTSuYV7cgPt0ObxxHSBF1alOQq5truE5N0jOn5Py5iDlxYrSVc87XA6iy0lWkW75LBA1g/nT/otuMjXD1KU+PNAuguMWKiCRT/74GepsbGA4zFXYpjO1akrEMhjhoaTWmDNWVKvigwQzEmNCh+xtXhJTkItNJzHOcWg1 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: On Fri, Aug 25, 2023 at 02:04:41AM +0000, SeongJae Park wrote: > Commit dd06e72e68bc ("Compiler Attributes: Add __counted_by macro") > added __counted_by() annotation. The underlying attribute for the > feature is still under development, but adopting it can improve the > readability of the code. Apply it to four dynamic arrays in DAMON sysfs > code. > > Signed-off-by: SeongJae Park > --- > mm/damon/sysfs.c | 8 ++++---- > 1 file changed, 4 insertions(+), 4 deletions(-) > > diff --git a/mm/damon/sysfs.c b/mm/damon/sysfs.c > index 808a8efe0523..36a176f38726 100644 > --- a/mm/damon/sysfs.c > +++ b/mm/damon/sysfs.c > @@ -93,7 +93,7 @@ static const struct kobj_type damon_sysfs_region_ktype = { > > struct damon_sysfs_regions { > struct kobject kobj; > - struct damon_sysfs_region **regions_arr; > + struct damon_sysfs_region **regions_arr __counted_by(nr); > int nr; > }; Unfortunately this isn't supported yet for non-flexible-array-members: mm/damon/sysfs.c:96:14: error: 'counted_by' attribute may not be specified for a non-array field 96 | struct damon_sysfs_region **regions_arr __counted_by(nr); | ^~~~~ We'll have to wait a bit before we can add this patch. Thank you for getting it ready, though! This support is next in line. :) The FAM support is likely ready to land, though[1]. I just tested it today. -Kees [1] https://gcc.gnu.org/pipermail/gcc-patches/2023-August/628459.html -- Kees Cook