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[204.195.96.226]) by smtp.gmail.com with ESMTPSA id 5a478bee46e88-304e94e54besm13974eec.4.2026.05.28.11.24.43 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 28 May 2026 11:24:44 -0700 (PDT) Date: Thu, 28 May 2026 11:24:40 -0700 From: Stephen Hemminger To: Wei Hu Cc: Wei Hu , "dev@dpdk.org" , Long Li Subject: Re: [EXTERNAL] Re: [PATCH v3 0/2] net/mana: add device reset support Message-ID: <20260528112440.3f7e25cc@phoenix.local> In-Reply-To: References: <20260522065943.126703-1-weh@linux.microsoft.com> <20260526123747.46871467@phoenix.local> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-BeenThere: dev@dpdk.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: DPDK patches and discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dev-bounces@dpdk.org On Thu, 28 May 2026 07:30:03 +0000 Wei Hu wrote: > > so they are invisible to rte_rcu_qsbr_check in the primary, and > > the secondary MP handler (mana_mp_reset_enter) does not call > > qsbr_check at all -- it just sets db_page = NULL and munmaps. > > > > The dev_state check at the top of secondary tx_burst is racy: > > the page can be munmapped after the in-loop read of db_page but > > before the doorbell write at the bottom. The "All secondary > > threads are quiescent" log line in mana_mp_reset_enter is not > > true. > > > > The secondary needs a real reader-side primitive -- its own > > qsbr with secondary lcore registration, or an rwlock the MP > > handler takes before munmap. > > > > Thanks for the v3 review, @Stephen. I will send out v4 to incorporate most > of the review comments except for this one. > > The review on this point is not correct. Here I am providing analysis from > AI and my own test results to show why. > > The concern is that "rte_rcu_qsbr_thread_register is only called > from mana_dev_configure, which the secondary never runs", so > secondary tids are unregistered and invisible to rte_rcu_qsbr_check. Thanks, I have become way to familiar with AI reaching false conclusions.