Re: [PATCH] vdpa: bypass waking up vhost_woker for vdpa vq kick

[Jason Wang]

On 2020/6/2 äå6:16, Jason Wang wrote:
> On 2020/6/2 äå5:42, 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@xxxxxxxxx>
> > Reported-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx>
> >
> > 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 2020-05-26Â 316Â static long 
> > vhost_vdpa_set_vring_kick(struct vhost_virtqueue *vq,
> > a84ddbf1ef29f1 Zhu Lingshan 2020-05-26 317ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ 
> > void __user *argp)
> > a84ddbf1ef29f1 Zhu Lingshan 2020-05-26Â 318Â {
> > a84ddbf1ef29f1 Zhu Lingshan 2020-05-26Â 319ÂÂÂÂÂ bool pollstart = 
> > false, pollstop = false;
> > a84ddbf1ef29f1 Zhu Lingshan 2020-05-26Â 320ÂÂÂÂÂ struct file 
> > *eventfp, *filep = NULL;
> > a84ddbf1ef29f1 Zhu Lingshan 2020-05-26Â 321ÂÂÂÂÂ struct 
> > vhost_vring_file f;
> > a84ddbf1ef29f1 Zhu Lingshan 2020-05-26Â 322ÂÂÂÂÂ long r;
> > a84ddbf1ef29f1 Zhu Lingshan 2020-05-26Â 323
> > a84ddbf1ef29f1 Zhu Lingshan 2020-05-26Â 324ÂÂÂÂÂ if 
> > (copy_from_user(&f, argp, sizeof(f)))
> > a84ddbf1ef29f1 Zhu Lingshan 2020-05-26Â 325ÂÂÂÂÂÂÂÂÂ return -EFAULT;
> > a84ddbf1ef29f1 Zhu Lingshan 2020-05-26Â 326
> > a84ddbf1ef29f1 Zhu Lingshan 2020-05-26Â 327ÂÂÂÂÂ eventfp = f.fd == -1 
> > ? NULL : eventfd_fget(f.fd);
> > a84ddbf1ef29f1 Zhu Lingshan 2020-05-26Â 328ÂÂÂÂÂ if (IS_ERR(eventfp)) {
> > a84ddbf1ef29f1 Zhu Lingshan 2020-05-26Â 329ÂÂÂÂÂÂÂÂÂ r = 
> > PTR_ERR(eventfp);
> > a84ddbf1ef29f1 Zhu Lingshan 2020-05-26Â 330ÂÂÂÂÂÂÂÂÂ return r;
> > a84ddbf1ef29f1 Zhu Lingshan 2020-05-26Â 331ÂÂÂÂÂ }
> > a84ddbf1ef29f1 Zhu Lingshan 2020-05-26Â 332
> > a84ddbf1ef29f1 Zhu Lingshan 2020-05-26Â 333ÂÂÂÂÂ if (eventfp != 
> > vq->kick) {
> > a84ddbf1ef29f1 Zhu Lingshan 2020-05-26Â 334ÂÂÂÂÂÂÂÂÂ pollstop = 
> > (filep = vq->kick) != NULL;
> > a84ddbf1ef29f1 Zhu Lingshan 2020-05-26Â 335ÂÂÂÂÂÂÂÂÂ pollstart = 
> > (vq->kick = eventfp) != NULL;
> > a84ddbf1ef29f1 Zhu Lingshan 2020-05-26Â 336ÂÂÂÂÂ } else
> > a84ddbf1ef29f1 Zhu Lingshan 2020-05-26Â 337ÂÂÂÂÂÂÂÂÂ filep = eventfp;
> > a84ddbf1ef29f1 Zhu Lingshan 2020-05-26Â 338
> > a84ddbf1ef29f1 Zhu Lingshan 2020-05-26Â 339ÂÂÂÂÂ if (pollstop && 
> > vq->handle_kick)
> > a84ddbf1ef29f1 Zhu Lingshan 2020-05-26Â 340 vhost_vdpa_poll_stop(vq);
> > a84ddbf1ef29f1 Zhu Lingshan 2020-05-26Â 341
> > a84ddbf1ef29f1 Zhu Lingshan 2020-05-26Â 342ÂÂÂÂÂ if (filep)
> > a84ddbf1ef29f1 Zhu Lingshan 2020-05-26Â 343 fput(filep);
> > a84ddbf1ef29f1 Zhu Lingshan 2020-05-26Â 344
> > a84ddbf1ef29f1 Zhu Lingshan 2020-05-26Â 345ÂÂÂÂÂ if (pollstart && 
> > vq->handle_kick)
> > a84ddbf1ef29f1 Zhu Lingshan 2020-05-26Â 346ÂÂÂÂÂÂÂÂÂ r = 
> > vhost_vdpa_poll_start(vq);
> >
> > "r" not initialized on else path.
> >
> > a84ddbf1ef29f1 Zhu Lingshan 2020-05-26Â 347
> > a84ddbf1ef29f1 Zhu Lingshan 2020-05-26 @348ÂÂÂÂÂ return r;
> > a84ddbf1ef29f1 Zhu Lingshan 2020-05-26Â 349Â }
>
>
> Will fix.
>
> Thanks 


Lingshan reminds me that we've posted V2 which reuses the vhost.c 
implementation for polling.

So there's no need for the fix.

Thanks