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[87.106.108.193]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-485883959f0sm7139278f8f.10.2026.09.04.07.17.47 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 04 Sep 2026 07:17:48 -0700 (PDT) Date: Fri, 4 Sep 2026 16:17:46 +0200 From: =?iso-8859-1?Q?G=FCnther?= Noack To: Ye Liu Cc: =?iso-8859-1?Q?Micka=EBl_Sala=FCn?= , Paul Moore , James Morris , "Serge E. Hallyn" , Ye Liu , =?iso-8859-1?Q?G=FCnther?= Noack , linux-security-module@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 8/8] security/landlock: convert thread iterator to for_each_thread_rcu Message-ID: <20260904.01fcdd4c37b2@gnoack.org> References: <20260904083001.553587-1-ye.liu@linux.dev> <20260904083001.553587-9-ye.liu@linux.dev> Precedence: bulk X-Mailing-List: linux-security-module@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20260904083001.553587-9-ye.liu@linux.dev> On Fri, Sep 04, 2026 at 04:30:00PM +0800, Ye Liu wrote: > From: Ye Liu > > Replace guard(rcu)() + for_each_thread() with for_each_thread_rcu(), > so that the RCU read-side critical section is scoped to the loop body. > > No functional change. > > Signed-off-by: Ye Liu > --- > security/landlock/tsync.c | 8 ++------ > 1 file changed, 2 insertions(+), 6 deletions(-) > > diff --git a/security/landlock/tsync.c b/security/landlock/tsync.c > index 0b71e158c3f5..f1c08aae179b 100644 > --- a/security/landlock/tsync.c > +++ b/security/landlock/tsync.c > @@ -335,9 +335,7 @@ static size_t count_additional_threads(const struct tsync_works *works) > > caller = current; > > - guard(rcu)(); > - > - for_each_thread(caller, thread) { > + for_each_thread_rcu(caller, thread) { > /* Skip current, since it is initiating the sync. */ > if (thread == caller) > continue; > @@ -376,9 +374,7 @@ static bool schedule_task_work(struct tsync_works *works, > > caller = current; > > - guard(rcu)(); > - > - for_each_thread(caller, thread) { > + for_each_thread_rcu(caller, thread) { > /* Skip current, since it is initiating the sync. */ > if (thread == caller) > continue; > -- > 2.25.1 > Reviewed-by: Günther Noack Looks good, provided that the for_each_thread_rcu() macro gets accepted. Although, I find that in the Landlock case, it does not provide a very strong advantage over the explicit "guard(rcu)();", and I find it normally preferrable to use orthogonal APIs. –Günther