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Thu, 04 Jun 2026 02:11:37 -0700 (PDT) Received: from [192.168.88.32] ([212.105.155.59]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-4601f0a43e9sm14825452f8f.0.2026.06.04.02.11.36 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 04 Jun 2026 02:11:36 -0700 (PDT) Message-ID: <95adff35-ee56-49d3-8567-382ac17810b3@redhat.com> Date: Thu, 4 Jun 2026 11:11:30 +0200 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 1/2] ipv4: igmp: annotate data-races around in_dev->mc_count To: Yuyang Huang Cc: "David S. Miller" , David Ahern , Eric Dumazet , Ido Schimmel , Jakub Kicinski , Simon Horman , linux-kernel@vger.kernel.org, netdev@vger.kernel.org References: <20260531030705.3754389-1-yuyanghuang@google.com> <20260531030705.3754389-2-yuyanghuang@google.com> From: Paolo Abeni Content-Language: en-US In-Reply-To: <20260531030705.3754389-2-yuyanghuang@google.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 5/31/26 5:07 AM, Yuyang Huang wrote: > @@ -1922,7 +1923,7 @@ void ip_mc_destroy_dev(struct in_device *in_dev) > > while ((i = rtnl_dereference(in_dev->mc_list)) != NULL) { > in_dev->mc_list = i->next_rcu; > - in_dev->mc_count--; > + WRITE_ONCE(in_dev->mc_count, in_dev->mc_count - 1); > ip_mc_clear_src(i); > ip_ma_put(i); The patch LGTM, but note that sashiko has identified a pre-existing issue which could deserve a follow-up: https://sashiko.dev/#/patchset/20260531030705.3754389-1-yuyanghuang%40google.com /P > } > @@ -2974,7 +2975,9 @@ static int igmp_mc_seq_show(struct seq_file *seq, void *v) > > if (rcu_access_pointer(state->in_dev->mc_list) == im) { > seq_printf(seq, "%d\t%-10s: %5d %7s\n", > - state->dev->ifindex, state->dev->name, state->in_dev->mc_count, querier); > + state->dev->ifindex, state->dev->name, > + READ_ONCE(state->in_dev->mc_count), > + querier); > } > > delta = im->timer.expires - jiffies;