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bh=JeAM4nWTpcUtADM4VJ4nzpi2Ew5kVIMLOrtrf3VwIPA=; b=ltYQMkvqxx4tzd/ntoKjZwrW6h iOE+bIqwyF4FcX5vW029HCyMEpSkQXRShlZDXfgUcw8X0qjDOArQ7C8epVKOgIP1IkBDWzTPRCqEc 4YZoO1kxwsEzDeH1kcvg2pkWJVeVfeNrdYpyUIxHVxRDY/IW0sNB98KLdCLMuIeoDsyo=; Received: from [95.248.141.113] (port=62969 helo=bywater) by esm19.siteground.biz with esmtpsa (TLS1.3) tls TLS_AES_256_GCM_SHA384 (Exim 4.98.1) (envelope-from ) id 1vaKHQ-00000000BS5-1TCH; Mon, 29 Dec 2025 20:55:52 +0000 Date: Mon, 29 Dec 2025 21:55:50 +0100 From: Francesco Valla To: Matias Ezequiel Vara Larsen Cc: Marc Kleine-Budde , Vincent Mailhol , Harald Mommer , Mikhail Golubev-Ciuchea , "Michael S. Tsirkin" , Jason Wang , Xuan Zhuo , linux-can@vger.kernel.org, virtualization@lists.linux.dev, Wolfgang Grandegger , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Stefano Garzarella Subject: Re: [PATCH v6] can: virtio: Add virtio CAN driver Message-ID: References: Precedence: bulk X-Mailing-List: virtualization@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-AntiAbuse: This header was added to track abuse, please include it with any abuse report X-AntiAbuse: Primary Hostname - esm19.siteground.biz X-AntiAbuse: Original Domain - lists.linux.dev X-AntiAbuse: Originator/Caller UID/GID - [47 12] / [47 12] X-AntiAbuse: Sender Address Domain - valla.it X-Source: X-Source-Args: X-Source-Dir: X-SGantispam-id: f756753f238d09354efc727cc5ca1870 AntiSpam-DLS: false AntiSpam-DLSP: AntiSpam-DLSRS: AntiSpam-TS: 1.0 CFBL-Address: feedback@antispam.mailspamprotection.com; report=arf CFBL-Feedback-ID: 1vaKHh-00000001Cxd-0Ill-feedback@antispam.mailspamprotection.com Authentication-Results: outgoing.instance-europe-west4-sc6w.prod.antispam.mailspamprotection.com; iprev=pass (214.173.214.35.bc.googleusercontent.com) smtp.remote-ip=35.214.173.214; auth=pass (LOGIN) smtp.auth=esm19.siteground.biz; dkim=pass header.d=valla.it header.s=default header.a=rsa-sha256; arc=none Hi Matias, On Mon, Dec 29, 2025 at 07:53:48PM +0100, Matias Ezequiel Vara Larsen wrote: > > While stress testing this, I noticed that flooding the virtio-can > > interface with packets leads to an hang of the interface itself. > > I am seeing this issuing, at host side: > > > > while true; do cansend can0 123#00; done > > > > with: > > > > - QEMU: the tip of the master branch plus [2] > > - vhost-device: the tip of the main branch > > > > and the following QEMU invocation: > > > > qemu-system-x86_64 -serial mon:stdio \ > > -m 2G -smp 2 \ > > -kernel $(pwd)/BUILD.bin/arch/x86/boot/bzImage \ > > -initrd /home/francesco/SRC/LINUX_KERNEL/initramfs.gz \ > > -append "loglevel=7 console=ttyS0" \ > > -machine memory-backend=pc.ram \ > > -object memory-backend-file,id=pc.ram,size=2G,mem-path=/tmp/pc.ram,share=on \ > > -chardev socket,id=can0,path=/tmp/sock-can0 \ > > -device vhost-user-can-pci,chardev=can0 > > > > > > Restarting the interface (i.e.: ip link set down and the up) does not > > fix the situation. > > > > I'll try to do some more testing during the next days. > > I tried this and I could not reproduce it. [2] requires a minimal change > to apply, i.e., qdev-properties.h has changed to /core. I'll send a v2 > for that. I used latest vhost-device-can. I run `candump can0` in the > guest and `while true; do cangen vcan0; done` in the host. Am I missing > something? With the plain 'cangen' you are not really flooding the interface, since you are only sending a random CAN frame every 200ms. The only way I can reproduce this behaviour in a consistent manner is running from the host: while true; do cansend vcan0 134#00; done which seems to generate the maximum amount of traffic. This is not of course a realistic bus load, but is leading the system (at least on my setup) to a corner case somewhere. > > Thanks, > > Matias > > Thank you for this effort! Regards, Francesco