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[78.154.15.142]) by smtp.gmail.com with ESMTPSA id a640c23a62f3a-ab705f83e1dsm707185066b.185.2025.02.04.08.36.03 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 04 Feb 2025 08:36:04 -0800 (PST) Message-ID: Date: Tue, 4 Feb 2025 18:36:03 +0200 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: [PATCH net-next 1/8] vxlan: Annotate FDB data races To: Ido Schimmel , netdev@vger.kernel.org Cc: davem@davemloft.net, kuba@kernel.org, pabeni@redhat.com, edumazet@google.com, andrew+netdev@lunn.ch, horms@kernel.org, petrm@nvidia.com References: <20250204145549.1216254-1-idosch@nvidia.com> <20250204145549.1216254-2-idosch@nvidia.com> Content-Language: en-US From: Nikolay Aleksandrov In-Reply-To: <20250204145549.1216254-2-idosch@nvidia.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 2/4/25 16:55, Ido Schimmel wrote: > The 'used' and 'updated' fields in the FDB entry structure can be > accessed concurrently by multiple threads, leading to reports such as > [1]. Can be reproduced using [2]. > > Suppress these reports by annotating these accesses using > READ_ONCE() / WRITE_ONCE(). > > [1] > BUG: KCSAN: data-race in vxlan_xmit / vxlan_xmit > > write to 0xffff942604d263a8 of 8 bytes by task 286 on cpu 0: > vxlan_xmit+0xb29/0x2380 > dev_hard_start_xmit+0x84/0x2f0 > __dev_queue_xmit+0x45a/0x1650 > packet_xmit+0x100/0x150 > packet_sendmsg+0x2114/0x2ac0 > __sys_sendto+0x318/0x330 > __x64_sys_sendto+0x76/0x90 > x64_sys_call+0x14e8/0x1c00 > do_syscall_64+0x9e/0x1a0 > entry_SYSCALL_64_after_hwframe+0x77/0x7f > > read to 0xffff942604d263a8 of 8 bytes by task 287 on cpu 2: > vxlan_xmit+0xadf/0x2380 > dev_hard_start_xmit+0x84/0x2f0 > __dev_queue_xmit+0x45a/0x1650 > packet_xmit+0x100/0x150 > packet_sendmsg+0x2114/0x2ac0 > __sys_sendto+0x318/0x330 > __x64_sys_sendto+0x76/0x90 > x64_sys_call+0x14e8/0x1c00 > do_syscall_64+0x9e/0x1a0 > entry_SYSCALL_64_after_hwframe+0x77/0x7f > > value changed: 0x00000000fffbac6e -> 0x00000000fffbac6f > > Reported by Kernel Concurrency Sanitizer on: > CPU: 2 UID: 0 PID: 287 Comm: mausezahn Not tainted 6.13.0-rc7-01544-gb4b270f11a02 #5 > Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.3-3.fc41 04/01/2014 > > [2] > #!/bin/bash > > set +H > echo whitelist > /sys/kernel/debug/kcsan > echo !vxlan_xmit > /sys/kernel/debug/kcsan > > ip link add name vx0 up type vxlan id 10010 dstport 4789 local 192.0.2.1 > bridge fdb add 00:11:22:33:44:55 dev vx0 self static dst 198.51.100.1 > taskset -c 0 mausezahn vx0 -a own -b 00:11:22:33:44:55 -c 0 -q & > taskset -c 2 mausezahn vx0 -a own -b 00:11:22:33:44:55 -c 0 -q & > > Reviewed-by: Petr Machata > Signed-off-by: Ido Schimmel > --- > drivers/net/vxlan/vxlan_core.c | 18 +++++++++--------- > 1 file changed, 9 insertions(+), 9 deletions(-) > Reviewed-by: Nikolay Aleksandrov