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([2620:10d:c090:500::5:5d68]) by smtp.gmail.com with ESMTPSA id d2e1a72fcca58-73e25912c70sm1635484b3a.29.2025.04.24.09.59.13 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 24 Apr 2025 09:59:14 -0700 (PDT) Message-ID: Date: Thu, 24 Apr 2025 09:59:12 -0700 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v4 2/5] cgroup: add helper for checking when css is cgroup::self To: Yosry Ahmed Cc: tj@kernel.org, shakeel.butt@linux.dev, yosryahmed@google.com, mkoutny@suse.com, hannes@cmpxchg.org, akpm@linux-foundation.org, linux-mm@kvack.org, cgroups@vger.kernel.org, kernel-team@meta.com References: <20250404011050.121777-1-inwardvessel@gmail.com> <20250404011050.121777-3-inwardvessel@gmail.com> <68078968.5d0a0220.2c3c35.bab3SMTPIN_ADDED_BROKEN@mx.google.com> Content-Language: en-US From: JP Kobryn In-Reply-To: <68078968.5d0a0220.2c3c35.bab3SMTPIN_ADDED_BROKEN@mx.google.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam10 X-Rspamd-Queue-Id: DCB3612000D X-Stat-Signature: jqg1fdyh1u4eu8zw8idofud1u53t6sk5 X-Rspam-User: X-HE-Tag: 1745513955-50212 X-HE-Meta: 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 aP6E/tmB trlBWUGly1SYkA8gBpwvdftkn4UTZj9BJyoYwYlvDjrRnyL8NayeqCza79Gdmwgw+6+A9E1GdZaaHUpqb96NBoEa4A//jxCfuo3fWXYq0rREptBt08SgmjRTrGEH5h9xq+HCP03QRgfoCynnBH9PDyo+tAlBxWOWnBVAvAmOh7WA2vxKJJQ3OwThQoq/AukkcirLXTRG5BylmdlEUWY4V2Yp3/0NPIKrqpg4ihOJ2a/rjuhZPgf8Fw60D2d0ru+jpP2S+mrfi9u4nJnXXh2YKU0M6QOTgmJFiuvzxReONgidO1oALRHQP+xj3E3FAPYSbYElNiUzC2CDKwDBAfI95XYIvnsODfsaZpASzyhFPADudNOGejR3+Qsl4xbXIUE7vzS4akTiY2uh1+TLgXyv6e0LMM3rFr0YdcWSSs03hbUDRIjcHYYedyZAq0rpBXs0edhxk6TYvhtFlQuKPE34QUjkyxg== 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: List-Subscribe: List-Unsubscribe: On 4/22/25 5:19 AM, Yosry Ahmed wrote: > On Thu, Apr 03, 2025 at 06:10:47PM -0700, JP Kobryn wrote: ... >> +static inline bool css_is_cgroup(struct cgroup_subsys_state *css) > > I think css_is_self() or css_is_cgroup_self() may be clearer given that > we are basically checking if css is the same as css->cgroup->self. As I > write this out, I am wondering why don't we check css == > css->cgroup->self instead (and perhaps add a WARN to make sure css->ss > is NULL as expected)? The check for css->cgroup->self seems reasonable. The intention of this patch was just to replace explicit checks for existence of css->ss. Regardless, since patches 1 to 3 of this series already been merged I think we can consider changing the implementation outside of this series. > > This seems clearer to me unless I am missing something. If the implementation changes, I think adding "_self" could make sense.