linux-kernel - Re: [PATCH] vdpa: bypass waking up vhost

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Date:   Tue, 2 Jun 2020 18:16:50 +0800
From:   Jason Wang <jasowang@...hat.com>
To:     Dan Carpenter <dan.carpenter@...cle.com>, kbuild@...ts.01.org,
        Zhu Lingshan <lingshan.zhu@...el.com>, mst@...hat.com,
        kvm@...r.kernel.org, virtualization@...ts.linux-foundation.org,
        linux-kernel@...r.kernel.org, netdev@...r.kernel.org
Cc:     lkp@...el.com, kbuild-all@...ts.01.org, lulu@...hat.com,
        dan.daly@...el.com, cunming.liang@...el.com
Subject: Re: [PATCH] vdpa: bypass waking up vhost_woker for vdpa vq kick


On 2020/6/2 下午5:42, Dan Carpenter wrote:
> Hi Zhu,
>
> url:    https://github.com/0day-ci/linux/commits/Zhu-Lingshan/vdpa-bypass-waking-up-vhost_woker-for-vdpa-vq-kick/20200526-133819
> base:   https://git.kernel.org/pub/scm/linux/kernel/git/mst/vhost.git linux-next
> config: x86_64-randconfig-m001-20200529 (attached as .config)
> compiler: gcc-9 (Debian 9.3.0-13) 9.3.0
>
> If you fix the issue, kindly add following tag as appropriate
> Reported-by: kbuild test robot <lkp@...el.com>
> Reported-by: Dan Carpenter <dan.carpenter@...cle.com>
>
> smatch warnings:
> drivers/vhost/vdpa.c:348 vhost_vdpa_set_vring_kick() error: uninitialized symbol 'r'.
>
> # https://github.com/0day-ci/linux/commit/a84ddbf1ef29f18aafb2bb8a93bcedd4a29a967d
> git remote add linux-review https://github.com/0day-ci/linux
> git remote update linux-review
> git checkout a84ddbf1ef29f18aafb2bb8a93bcedd4a29a967d
> vim +/r +348 drivers/vhost/vdpa.c
>
> a84ddbf1ef29f1 Zhu Lingshan 2020-05-26  316  static long vhost_vdpa_set_vring_kick(struct vhost_virtqueue *vq,
> a84ddbf1ef29f1 Zhu Lingshan 2020-05-26  317  				      void __user *argp)
> a84ddbf1ef29f1 Zhu Lingshan 2020-05-26  318  {
> a84ddbf1ef29f1 Zhu Lingshan 2020-05-26  319  	bool pollstart = false, pollstop = false;
> a84ddbf1ef29f1 Zhu Lingshan 2020-05-26  320  	struct file *eventfp, *filep = NULL;
> a84ddbf1ef29f1 Zhu Lingshan 2020-05-26  321  	struct vhost_vring_file f;
> a84ddbf1ef29f1 Zhu Lingshan 2020-05-26  322  	long r;
> a84ddbf1ef29f1 Zhu Lingshan 2020-05-26  323
> a84ddbf1ef29f1 Zhu Lingshan 2020-05-26  324  	if (copy_from_user(&f, argp, sizeof(f)))
> a84ddbf1ef29f1 Zhu Lingshan 2020-05-26  325  		return -EFAULT;
> a84ddbf1ef29f1 Zhu Lingshan 2020-05-26  326
> a84ddbf1ef29f1 Zhu Lingshan 2020-05-26  327  	eventfp = f.fd == -1 ? NULL : eventfd_fget(f.fd);
> a84ddbf1ef29f1 Zhu Lingshan 2020-05-26  328  	if (IS_ERR(eventfp)) {
> a84ddbf1ef29f1 Zhu Lingshan 2020-05-26  329  		r = PTR_ERR(eventfp);
> a84ddbf1ef29f1 Zhu Lingshan 2020-05-26  330  		return r;
> a84ddbf1ef29f1 Zhu Lingshan 2020-05-26  331  	}
> a84ddbf1ef29f1 Zhu Lingshan 2020-05-26  332
> a84ddbf1ef29f1 Zhu Lingshan 2020-05-26  333  	if (eventfp != vq->kick) {
> a84ddbf1ef29f1 Zhu Lingshan 2020-05-26  334  		pollstop = (filep = vq->kick) != NULL;
> a84ddbf1ef29f1 Zhu Lingshan 2020-05-26  335  		pollstart = (vq->kick = eventfp) != NULL;
> a84ddbf1ef29f1 Zhu Lingshan 2020-05-26  336  	} else
> a84ddbf1ef29f1 Zhu Lingshan 2020-05-26  337  		filep = eventfp;
> a84ddbf1ef29f1 Zhu Lingshan 2020-05-26  338
> a84ddbf1ef29f1 Zhu Lingshan 2020-05-26  339  	if (pollstop && vq->handle_kick)
> a84ddbf1ef29f1 Zhu Lingshan 2020-05-26  340  		vhost_vdpa_poll_stop(vq);
> a84ddbf1ef29f1 Zhu Lingshan 2020-05-26  341
> a84ddbf1ef29f1 Zhu Lingshan 2020-05-26  342  	if (filep)
> a84ddbf1ef29f1 Zhu Lingshan 2020-05-26  343  		fput(filep);
> a84ddbf1ef29f1 Zhu Lingshan 2020-05-26  344
> a84ddbf1ef29f1 Zhu Lingshan 2020-05-26  345  	if (pollstart && vq->handle_kick)
> a84ddbf1ef29f1 Zhu Lingshan 2020-05-26  346  		r = vhost_vdpa_poll_start(vq);
>
> "r" not initialized on else path.
>
> a84ddbf1ef29f1 Zhu Lingshan 2020-05-26  347
> a84ddbf1ef29f1 Zhu Lingshan 2020-05-26 @348  	return r;
> a84ddbf1ef29f1 Zhu Lingshan 2020-05-26  349  }


Will fix.

Thanks


> ---
> 0-DAY CI Kernel Test Service, Intel Corporation
> https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org