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[103.168.172.200]) by smtp.gmail.com with ESMTPSA id af79cd13be357-7c0b3bf7374sm136188485a.95.2025.02.19.08.00.15 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 19 Feb 2025 08:00:15 -0800 (PST) Received: from phl-compute-12.internal (phl-compute-12.phl.internal [10.202.2.52]) by mailfauth.phl.internal (Postfix) with ESMTP id 5D6A71200043; Wed, 19 Feb 2025 11:00:15 -0500 (EST) Received: from phl-mailfrontend-02 ([10.202.2.163]) by phl-compute-12.internal (MEProxy); Wed, 19 Feb 2025 11:00:15 -0500 X-ME-Sender: X-ME-Received: X-ME-Proxy-Cause: gggruggvucftvghtrhhoucdtuddrgeefvddrtddtgdeigeeikecutefuodetggdotefrod ftvfcurfhrohhfihhlvgemucfhrghsthforghilhdpggftfghnshhusghstghrihgsvgdp uffrtefokffrpgfnqfghnecuuegrihhlohhuthemuceftddtnecusecvtfgvtghiphhivg hnthhsucdlqddutddtmdenucfjughrpeffhffvvefukfhfgggtuggjsehttdertddttddv necuhfhrohhmpeeuohhquhhnucfhvghnghcuoegsohhquhhnrdhfvghnghesghhmrghilh drtghomheqnecuggftrfgrthhtvghrnhephedugfduffffteeutddvheeuveelvdfhleel ieevtdeguefhgeeuveeiudffiedvnecuvehluhhsthgvrhfuihiivgeptdenucfrrghrrg hmpehmrghilhhfrhhomhepsghoqhhunhdomhgvshhmthhprghuthhhphgvrhhsohhnrghl ihhthidqieelvdeghedtieegqddujeejkeehheehvddqsghoqhhunhdrfhgvnhhgpeepgh hmrghilhdrtghomhesfhhigihmvgdrnhgrmhgvpdhnsggprhgtphhtthhopeekpdhmohgu vgepshhmthhpohhuthdprhgtphhtthhopehrihgthhgrrhgurdifvghihigrnhhgsehgmh grihhlrdgtohhmpdhrtghpthhtohepphgruhhlmhgtkheskhgvrhhnvghlrdhorhhgpdhr tghpthhtohepfhhrvgguvghrihgtsehkvghrnhgvlhdrohhrghdprhgtphhtthhopehnvg gvrhgrjhdruhhprgguhhihrgihsehkvghrnhgvlhdrohhrghdprhgtphhtthhopehrtghu sehvghgvrhdrkhgvrhhnvghlrdhorhhgpdhrtghpthhtoheplhhinhhugidqughotgesvh hgvghrrdhkvghrnhgvlhdrohhrghdprhgtphhtthhopehmmhhpghhouhhrihguvgesghhm rghilhdrtghomhdprhgtphhtthhopegsohhquhhnsehfihigmhgvrdhnrghmvg X-ME-Proxy: Feedback-ID: iad51458e:Fastmail Received: by mail.messagingengine.com (Postfix) with ESMTPA; Wed, 19 Feb 2025 11:00:14 -0500 (EST) Date: Wed, 19 Feb 2025 08:00:13 -0800 From: Boqun Feng To: Wei Yang Cc: paulmck@kernel.org, frederic@kernel.org, neeraj.upadhyay@kernel.org, rcu@vger.kernel.org, linux-doc@vger.kernel.org, Alan Huang Subject: Re: [Patch v2] doc/RCU/listRCU: refine example code for eliminating stale data Message-ID: References: <20250218005047.27258-1-richard.weiyang@gmail.com> Precedence: bulk X-Mailing-List: linux-doc@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20250218005047.27258-1-richard.weiyang@gmail.com> On Tue, Feb 18, 2025 at 12:50:47AM +0000, Wei Yang wrote: > This patch adjust the example code with following two purpose: > > * reduce the confusion on not releasing e->lock > * emphasize e is valid and not stale with e->lock held > > Signed-off-by: Wei Yang > CC: Boqun Feng > CC: Alan Huang > Alan, could you take a look and if all looks reasonable to you, maybe a Reviewed-by or Acked-by? Thanks! Regards, Boqun > --- > v2: > * add the missing parameter *key > * make function return struct audit_entry > --- > Documentation/RCU/listRCU.rst | 10 ++++++---- > 1 file changed, 6 insertions(+), 4 deletions(-) > > diff --git a/Documentation/RCU/listRCU.rst b/Documentation/RCU/listRCU.rst > index ed5c9d8c9afe..d8bb98623c12 100644 > --- a/Documentation/RCU/listRCU.rst > +++ b/Documentation/RCU/listRCU.rst > @@ -334,7 +334,7 @@ If the system-call audit module were to ever need to reject stale data, one way > to accomplish this would be to add a ``deleted`` flag and a ``lock`` spinlock to the > ``audit_entry`` structure, and modify audit_filter_task() as follows:: > > - static enum audit_state audit_filter_task(struct task_struct *tsk) > + static struct audit_entry *audit_filter_task(struct task_struct *tsk, char **key) > { > struct audit_entry *e; > enum audit_state state; > @@ -346,16 +346,18 @@ to accomplish this would be to add a ``deleted`` flag and a ``lock`` spinlock to > if (e->deleted) { > spin_unlock(&e->lock); > rcu_read_unlock(); > - return AUDIT_BUILD_CONTEXT; > + return NULL; > } > rcu_read_unlock(); > if (state == AUDIT_STATE_RECORD) > *key = kstrdup(e->rule.filterkey, GFP_ATOMIC); > - return state; > + /* As long as e->lock is held, e is valid and > + * its value is not stale */ > + return e; > } > } > rcu_read_unlock(); > - return AUDIT_BUILD_CONTEXT; > + return NULL; > } > > The ``audit_del_rule()`` function would need to set the ``deleted`` flag under the > -- > 2.34.1 > >