Re: [PATCH v6 3/3] printk: fix double printing with earlycon

From: Aleksey Makarov
Date: Fri Mar 17 2017 - 09:40:56 EST




On 03/17/2017 02:43 PM, Aleksey Makarov wrote:

[..]

> @@ -2457,40 +2491,50 @@ void register_console(struct console *newcon)
> }
>
> /*
> - * See if this console matches one we selected on
> - * the command line.
> + * See if this console matches one we selected on the command line.
> + * Do it in three steps:
> + *
> + * 1) check if it is a braille console..
> */
> - for (i = 0, c = console_cmdline;
> - i < MAX_CMDLINECONSOLES && c->name[0];
> - i++, c++) {
> - if (!newcon->match ||
> - newcon->match(newcon, c->name, c->index, c->options) != 0) {
> - /* default matching */
> - BUILD_BUG_ON(sizeof(c->name) != sizeof(newcon->name));
> - if (strcmp(c->name, newcon->name) != 0)
> - continue;
> - if (newcon->index >= 0 &&
> - newcon->index != c->index)
> - continue;
> - if (newcon->index < 0)
> - newcon->index = c->index;
> -
> - if (_braille_register_console(newcon, c))
> - return;
> -
> - if (newcon->setup &&
> - newcon->setup(newcon, c->options) != 0)
> - break;
> - }
> + for_each_console_cmdline(i, c)
> + if (_braille_is_braille_console(c) &&
> + match_console_name(newcon, c) &&
> + _braille_register_console(newcon, c))
> + return;

I am sorry to say that, but it looks like this does not work either.
newcon->index still can be changed here in match_console_name(),
but (correctly implemented) _braille_register_console() may refuse
to register it, and the changed newcon is passed to newcon->match() below.

I tried the shuffle (i. e. v5) approach again and it seems I managed to
write quite nice code. I am going to send it in a minute.

Thank you
Aleksey Makarov

> - newcon->flags |= CON_ENABLED;
> - if (i == preferred_console) {
> + /*
> + * 2) check if this console was set as preferred by command line
> + * parameters or by call to add_preferred_console(). There may be
> + * several entries in the console_cmdline array matching with the same
> + * console, one with newcon->match(), another by name/index:
> + *
> + * pl011,mmio,0x87e024000000,115200 -- added from SPCR
> + * ttyAMA0 -- added from command line
> + *
> + * so we can not use the first match. Instead check the
> + * entry pointed by preferred_console and then all other entries.
> + */
> + if (preferred_console >= 0 &&
> + match_console(newcon, console_cmdline + preferred_console)) {
> + if (newcon->flags & CON_ENABLED) {
> newcon->flags |= CON_CONSDEV;
> has_preferred = true;
> }
> - break;
> + goto match;
> + }
> +
> + /*
> + * 3) check other entries
> + */
> + for_each_console_cmdline(i, c) {
> + if (preferred_console == i || _braille_is_braille_console(c))
> + continue;
> +
> + if (match_console(newcon, c))
> + goto match;
> }
>
> +match:
> if (!(newcon->flags & CON_ENABLED))
> return;
>
>