Linux Virtualization - Oct 2021 - [PATCH v11 2/3] tty: hvc: pass DMA capable memory to put_chars()

On Tue, Oct 26, 2021 at 02:02:21PM +0800, Xianting Tian
wrote:
> ? 2021/10/26 ??1:10, Jiri Slaby ??:
> > 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