On Mon, 22 Jan 2024 11:14:30 +0800, Jason Wang <jasow...@redhat.com> wrote: > On Mon, Jan 22, 2024 at 10:12 AM Zhu Yanjun <yanjun....@linux.dev> wrote: > > > > > > 在 2024/1/20 1:29, Andrew Lunn 写道: > > >>>>> while (!virtqueue_get_buf(vi->cvq, &tmp) && > > >>>>> - !virtqueue_is_broken(vi->cvq)) > > >>>>> + !virtqueue_is_broken(vi->cvq)) { > > >>>>> + if (timeout) > > >>>>> + timeout--; > > >>>> This is not really a timeout, just a loop counter. 200 iterations could > > >>>> be a very short time on reasonable H/W. I guess this avoid the soft > > >>>> lockup, but possibly (likely?) breaks the functionality when we need to > > >>>> loop for some non negligible time. > > >>>> > > >>>> I fear we need a more complex solution, as mentioned by Micheal in the > > >>>> thread you quoted. > > >>> Got it. I also look forward to the more complex solution to this > > >>> problem. > > >> Can we add a device capability (new feature bit) such as > > >> ctrq_wait_timeout > > >> to get a reasonable timeout? > > > The usual solution to this is include/linux/iopoll.h. If you can sleep > > > read_poll_timeout() otherwise read_poll_timeout_atomic(). > > > > I read carefully the functions read_poll_timeout() and > > read_poll_timeout_atomic(). The timeout is set by the caller of the 2 > > functions. > > FYI, in order to avoid a swtich of atomic or not, we need convert rx > mode setting to workqueue first: > > https://www.mail-archive.com/virtualization@lists.linux-foundation.org/msg60298.html > > > > > As such, can we add a module parameter to customize this timeout value > > by the user? > > Who is the "user" here, or how can the "user" know the value? > > > > > Or this timeout value is stored in device register, virtio_net driver > > will read this timeout value at initialization? > > See another thread. The design needs to be general, or you can post a RFC. > > In another thought, we've already had a tx watchdog, maybe we can have > something similar to cvq and use timeout + reset in that case.
But we may block by the reset ^_^ if the device is broken? Thanks. > > Thans > > > > > Zhu Yanjun > > > > > > > > Andrew > > >