Re: [PATCH 2/2] virtio-console: remove unnecessary kmemdup()

[Jiri Slaby]

On 02. 08. 21, 10:32, Xianting Tian wrote:
> 在 2021/8/2 下午3:25, Jiri Slaby 写道:
> > Hi,
> >
> > why is this 2/2? I seem (Lore neither) to find 1/2.
> You didn't receive 1/2?
> [PATCH 1/2] tty: hvc: pass DMA capable memory to put_chars()
> https://lkml.org/lkml/2021/8/1/8 <https://lkml.org/lkml/2021/8/1/8>

Oh, I did, but it's not properly threaded. PLease fix your setup.

> > On 01. 08. 21, 7:16, Xianting Tian wrote:
> > > hvc framework will never pass stack memory to the put_chars() function,
> >
> > Am I blind or missing something?
> >
> > hvc_console_print(...)
> > {
> >   char c[N_OUTBUF]
> > ...
> >   cons_ops[index]->put_chars(vtermnos[index], c, i);
> >
> > The same here:
> >
> > hvc_poll_put_char(..., char ch)
> > {
> > ...
> >    n = hp->ops->put_chars(hp->vtermno, &ch, 1);
> >
> > AFAICS both of them *pass* a pointer to stack variable.
>
> yes, I discussed the issue with Arnd before in below thread,  you can 
> get the history, thanks
>
> https://lkml.org/lkml/2021/7/27/494 <https://lkml.org/lkml/2021/7/27/494>

So is this a v2? You should have noted that. And what changed from v1 too.

> > > So the calling of kmemdup() is unnecessary, remove it.
> > >
> > > Fixes: c4baad5029 ("virtio-console: avoid DMA from stack")
> >
> > This patch doesn't "Fix" -- it reverts the commit. You should've CCed 
> > the author too.
>
> yes, we discussed ther issue in above thread, which we CCed the author.

I don't see any input from the author?


Anyway, 1/2 does not even build, so you will send v3 with all the above 
fixed, hopefully.

thanks,
--
js