Re: [PATCH v11 2/3] tty: hvc: pass DMA capable memory to put_chars()

[Greg KH]

On Tue, Oct 26, 2021 at 02:11:51PM +0800, Xianting Tian wrote:
> 
> 在 2021/10/26 下午2:10, Greg KH 写道:
> > On Tue, Oct 26, 2021 at 02:02:21PM +0800, Xianting Tian wrote:
> > > 在 2021/10/26 下午1:10, Jiri Slaby 写道:
> > > > On 15. 10. 21, 4:46, Xianting Tian wrote:
> > > > > @@ -151,9 +142,11 @@ static uint32_t vtermnos[MAX_NR_HVC_CONSOLES] =
> > > > >    static void hvc_console_print(struct console *co, const char *b,
> > > > >      unsigned count)
> > > > >    {
> > > > > -    char c[N_OUTBUF] __ALIGNED__;
> > > > > +    char *c;
> > > > >    unsigned i = 0, n = 0;
> > > > >    int r, donecr = 0, index = co->index;
> > > > > +    unsigned long flags;
> > > > > +    struct hvc_struct *hp;
> > > > >      /* Console access attempt outside of acceptable console
> > > > > range. */
> > > > >    if (index >= MAX_NR_HVC_CONSOLES)
> > > > > @@ -163,6 +156,13 @@ static void hvc_console_print(struct console
> > > > > *co, const char *b,
> > > > >    if (vtermnos[index] == -1)
> > > > >    return;
> > > > >    +    hp = cons_hvcs[index];
> > > > > +    if (!hp)
> > > > > +    return;
> > > > You effectively make the console unusable until someone calls
> > > > hvc_alloc() for this device, correct? This doesn't look right. Neither
> > > > you describe this change of behaviour in the commit log.
> > > I mentioned such info in the commit log:
> > > 'Introduce another array(cons_hvcs[]) for hvc pointers next to the
> > > cons_ops[] and vtermnos[] arrays. With the array, we can easily find
> > > hvc's cons_outbuf and its lock.'
> > > 
> > > After you pointed it out, I just found what you said make sense, I 
> > > checked the code hvc_console_print() can support print before hvc_alloc() 
> > > is called when someone use hvc_instantiate() for an early console 
> > > discovery method.
> > > I send a patch to fix the issue?  or these serial pathches reverted 
> > > fisrtly then I resend new version patches? thanks
> > Let me revert these now and you can send an updated version.
> OK, thanks.

I have now reverted patches 2/3 and 3/3 in this series from my tree.
The first patch was just fine.

thanks,

greg k-h
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Re: [PATCH v11 2/3] tty: hvc: pass DMA capable memory to put_chars()

[Greg KH]

On Tue, Oct 26, 2021 at 02:02:21PM +0800, Xianting Tian wrote:
> 在 2021/10/26 下午1:10, Jiri Slaby 写道:
> > On 15. 10. 21, 4:46, Xianting Tian wrote:
> > > @@ -151,9 +142,11 @@ static uint32_t vtermnos[MAX_NR_HVC_CONSOLES] =
> > >   static void hvc_console_print(struct console *co, const char *b,
> > >     unsigned count)
> > >   {
> > > -    char c[N_OUTBUF] __ALIGNED__;
> > > +    char *c;
> > >   unsigned i = 0, n = 0;
> > >   int r, donecr = 0, index = co->index;
> > > +    unsigned long flags;
> > > +    struct hvc_struct *hp;
> > >     /* Console access attempt outside of acceptable console
> > > range. */
> > >   if (index >= MAX_NR_HVC_CONSOLES)
> > > @@ -163,6 +156,13 @@ static void hvc_console_print(struct console
> > > *co, const char *b,
> > >   if (vtermnos[index] == -1)
> > >   return;
> > >   +    hp = cons_hvcs[index];
> > > +    if (!hp)
> > > +    return;
> > 
> > You effectively make the console unusable until someone calls
> > hvc_alloc() for this device, correct? This doesn't look right. Neither
> > you describe this change of behaviour in the commit log.
> 
> I mentioned such info in the commit log:
> 'Introduce another array(cons_hvcs[]) for hvc pointers next to the
> cons_ops[] and vtermnos[] arrays. With the array, we can easily find
> hvc's cons_outbuf and its lock.'
> 
> After you pointed it out, I just found what you said make sense, I checked 
> the code hvc_console_print() can support print before hvc_alloc() is called 
> when someone use hvc_instantiate() for an early console discovery method.
> I send a patch to fix the issue?  or these serial pathches reverted fisrtly 
> then I resend new version patches? thanks

Let me revert these now and you can send an updated version.

thanks,

greg k-h
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Re: [PATCH v11 2/3] tty: hvc: pass DMA capable memory to put_chars()

[Greg KH]

A: http://en.wikipedia.org/wiki/Top_post
Q: Were do I find info about this thing called top-posting?
A: Because it messes up the order in which people normally read text.
Q: Why is top-posting such a bad thing?
A: Top-posting.
Q: What is the most annoying thing in e-mail?

A: No.
Q: Should I include quotations after my reply?

http://daringfireball.net/2007/07/on_top

On Wed, Oct 20, 2021 at 04:47:23PM +0800, Xianting Tian wrote:
> hi Greg，
> 
> Could I get  your comments of this new version patches？ thanks

It has been less than 5 days.  Please relax, and only worry after 2
weeks have gone by.  We have lots of patches to review.  To help
maintainers out, why don't you review other patches on the mailing lists
as well while you wait?

thanks,

greg k-h
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