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McKenney" , openipmi-developer@lists.sourceforge.net, linux-kernel@vger.kernel.org, kernel-team@meta.com Subject: Re: [PATCH] ipmi: fix suspicious RCU usage warning Message-ID: Reply-To: corey@minyard.net References: <20250312131932.44d901f7@fangorn> <20250317-horned-nano-degu-a6e5bc@leitao> Precedence: bulk X-Mailing-List: linux-kernel@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: <20250317-horned-nano-degu-a6e5bc@leitao> On Mon, Mar 17, 2025 at 02:33:31AM -0700, Breno Leitao wrote: > On Wed, Mar 12, 2025 at 01:19:32PM -0400, Rik van Riel wrote: > > On recent kernels this warning fires: > > > > drivers/char/ipmi/ipmi_msghandler.c:1238 RCU-list traversed in non-reader section!! > > > > This looks like a fairly simple lockdep trigger, where > > list_for_each_entry_rcu and list_for_each_entry_srcu are > > functionally identical, but the lockdep annotation in > > the former has an extra check. > > > > That extra check is whether the RCU read lock is held, > > which is not true when the code uses srcu_read_lock. > > > > Get rid of the warning by using the properly annotated > > list traversal macro. > > Thanks for looking at this one. > > There was a discussion about this issue a few years ago, with > a different approach that never landed upstream. > > https://lore.kernel.org/all/20201119123831.GH3710@minyard.net/#r I thought this looked familiar. Breno, I believe you suggested a change to the patch that sounded reasonable, so I removed the patch, and then nothing happened and I didn't follow up. This is kind of a mess :-(. Let me look at it. -corey