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[89.177.130.96]) by smtp.gmail.com with ESMTPSA id j5sm4914621wrw.24.2020.02.21.09.54.36 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 21 Feb 2020 09:54:37 -0800 (PST) Date: Fri, 21 Feb 2020 18:54:36 +0100 From: Jiri Pirko To: Madhuparna Bhowmik Cc: jiri@mellanox.com, davem@davemloft.net, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, joel@joelfernandes.org, frextrite@gmail.com, linux-kernel-mentees@lists.linuxfoundation.org, paulmck@kernel.org Subject: Re: [PATCH] net: core: devlink.c: Use built-in RCU list checking Message-ID: <20200221175436.GB2181@nanopsycho> References: <20200221165141.24630-1-madhuparnabhowmik10@gmail.com> <20200221172008.GA2181@nanopsycho> <20200221173533.GA13198@madhuparna-HP-Notebook> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200221173533.GA13198@madhuparna-HP-Notebook> Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org Fri, Feb 21, 2020 at 06:35:34PM CET, madhuparnabhowmik10@gmail.com wrote: >On Fri, Feb 21, 2020 at 06:20:08PM +0100, Jiri Pirko wrote: >> Fri, Feb 21, 2020 at 05:51:41PM CET, madhuparnabhowmik10@gmail.com wrote: >> >From: Madhuparna Bhowmik >> > >> >list_for_each_entry_rcu() has built-in RCU and lock checking. >> > >> >Pass cond argument to list_for_each_entry_rcu() to silence >> >false lockdep warning when CONFIG_PROVE_RCU_LIST is enabled >> >by default. >> > >> >Signed-off-by: Madhuparna Bhowmik >> >> Reviewed-by: Jiri Pirko >> >> Thanks. >> >> However, there is a callpath where not devlink lock neither rcu read is >> taken: >> devlink_dpipe_table_register()->devlink_dpipe_table_find() >> >Hi, > >Yes I had noticed this, but I was not sure if there is some other lock >which is being used. > >If yes, then can you please tell me which lock is held in this case, >and I can add that condition as well to list_for_each_entry_rcu() usage. > >And if no lock or rcu_read_lock is held then may be we should >use rcu_read_lock/unlock here. > >Let me know what you think about this. devlink->lock should be held since the beginning of devlink_dpipe_table_register()