Re: [PATCH 5/6] tools: hv: Add new fcopy application based on uio driver

Saurabh Singh Sengar
2024-02-19T10:23:54Z

On Mon, Feb 19, 2024 at 10:52:12AM +0100, Greg KH wrote:
> On Mon, Feb 19, 2024 at 01:24:21AM -0800, Saurabh Singh Sengar wrote:
> > > > +#define HV_RING_SIZE (4 * 4096)
> > >
> > > Hey, that doesn't match the kernel driver! Why these values?
> >
> > This application talks to device which is recognize as HV_FCOPY
> > is kernel. In the first patch of current patch series I have
> > mentioned .pref_ring_size = 0x4000 for HV_FCOPY which matches this.
> >
> > This code is well tested.
>
> I'm commenting on the fact the 4096 is sometimes PAGE_SIZE and sometimes
> not, and you have a default of using PAGE_SIZE values in the kernel
> driver, and as such, this will not match up. So be careful here.

Thanks for clarification, I will add some note for it in V2.

>
> > > > +
> > > > +unsigned char desc[HV_RING_SIZE];
> > > > +
> > > > +static int target_fd;
> > > > +static char target_fname[PATH_MAX];
> > > > +static unsigned long long filesize;
> > > > +
> > > > +static int hv_fcopy_create_file(char *file_name, char *path_name, __u32 flags)
> > > > +{
> > > > + int error = HV_E_FAIL;
> > > > + char *q, *p;
> > > > +
> > > > + filesize = 0;
> > > > + p = (char *)path_name;
> > >
> > > Why the unneeded cast?
> >
> > This code is existing today as form of hv_fcopy_daemon. As this new
> > application is replacing hv_fcopy_daemon I reused the same code and
> > casting.
>
> That wasn't obvious that this was copied code, please be explicit about
> that.
>
> thanks,
>
> greg k-h