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Thu, 04 Dec 2025 01:25:06 -0800 (PST) X-Google-Smtp-Source: AGHT+IGHjvJVp3Q6NIJehYvKFw1+VG08krfj0o2zOuN0+0X29DCI8T/sHlFf0MSXLhEUByimYbuJ3A== X-Received: by 2002:a05:6000:40e0:b0:42b:3d9d:c605 with SMTP id ffacd0b85a97d-42f731c8442mr5415628f8f.49.1764840306405; Thu, 04 Dec 2025 01:25:06 -0800 (PST) Received: from [192.168.88.32] ([212.105.153.24]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-42f7cbe8fe8sm2153754f8f.2.2025.12.04.01.25.05 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 04 Dec 2025 01:25:05 -0800 (PST) Message-ID: <1b9ade5b-bfa9-4bcd-9bc4-6457dffcd887@redhat.com> Date: Thu, 4 Dec 2025 10:25:04 +0100 Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [net PATCH] net: macb: Relocate mog_init_rings() callback from macb_mac_link_up() to macb_open() To: Xiaolei Wang , nicolas.ferre@microchip.com, claudiu.beznea@tuxon.dev, andrew+netdev@lunn.ch, davem@davemloft.net, edumazet@google.com, kuba@kernel.org, Kexin.Hao@windriver.com Cc: netdev@vger.kernel.org, linux-kernel@vger.kernel.org References: <20251128103647.351259-1-xiaolei.wang@windriver.com> Content-Language: en-US From: Paolo Abeni In-Reply-To: <20251128103647.351259-1-xiaolei.wang@windriver.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 11/28/25 11:36 AM, Xiaolei Wang wrote: > In the non-RT kernel, local_bh_disable() merely disables preemption, > whereas it maps to an actual spin lock in the RT kernel. Consequently, > when attempting to refill RX buffers via netdev_alloc_skb() in > macb_mac_link_up(), a deadlock scenario arises as follows: > The dependency chain caused by macb_mac_link_up(): > &bp->lock --> (softirq_ctrl.lock) --> _xmit_ETHER#2 I'm sorry, but I can't see how this dependency chain is caused by mog_init_rings(), please extend the above info pin pointing the function/code effectively acquiring the lock and how it's reached. > The dependency chain caused by macb_start_xmit(): > _xmit_ETHER#2 --> &bp->lock > > Notably, invoking the mog_init_rings() callback upon link establishment > is unnecessary. Instead, we can exclusively call mog_init_rings() within > the ndo_open() callback. This adjustment resolves the deadlock issue. > Given that mog_init_rings() is only applicable to > non-MACB_CAPS_MACB_IS_EMAC cases, we can simply move it to macb_open() > and simultaneously eliminate the MACB_CAPS_MACB_IS_EMAC check. > > Suggested-by: Kevin Hao > Signed-off-by: Xiaolei Wang Please include a suitable fixes tag. Thanks, Paolo