On Wed, 1 Mar 2017 19:13:46 +0300
Aleksey Makarov <aleksey.maka...@linaro.org> wrote:
> If a console was specified by ACPI SPCR table _and_
> command line parameters like "console=ttyAMA0" _and_ "earlycon"
> were specified, then log messages appears twice.
>
> The root cause is that the code traverse the list
> of specified consoles (the `console_cmdline` array) and stops at the
> first match. But it may happen that the same console is referred by
> the elements of this array twice:
>
> ttyAMA0 -- from command line
> pl011,mmio,0x87e024000000,115200 -- from SPCR
>
> but in this case `preferred_console` points to the second entry and
> the flag CON_CONSDEV is not set, so bootconsole is not deregistered.
>
> To fix that, match the console against the `console_cmdline` entry
> pointed by `preferred_console` instead of the first match.
>
> Signed-off-by: Aleksey Makarov <aleksey.maka...@linaro.org>
> ---
> kernel/printk/printk.c | 52
> ++++++++++++++++++++++++++++++--------------------
> 1 file changed, 31 insertions(+), 21 deletions(-)
>
> diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c
> index ed2a9b31f214..92008ae9db3f 100644
> --- a/kernel/printk/printk.c
> +++ b/kernel/printk/printk.c
> @@ -2380,6 +2380,24 @@ static int __init keep_bootcon_setup(char *str)
>
> early_param("keep_bootcon", keep_bootcon_setup);
>
> +static int match_console(struct console *newcon, struct console_cmdline *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)
> + return -ENODEV;
> + if (newcon->index >= 0 &&
> + newcon->index != c->index)
> + return -ENODEV;
> + if (newcon->index < 0)
> + newcon->index = c->index;
> + }
> +
> + return 0;
> +}
> +
> /*
> * The console driver calls this routine during kernel initialization
> * to register the console printing procedure with printk() and to
> @@ -2460,37 +2478,29 @@ void register_console(struct console *newcon)
> 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 (match_console(newcon, c))
> + continue;
>
> - if (_braille_register_console(newcon, c))
> - return;
> + if (_braille_register_console(newcon, c))
> + return;
>
> - if (newcon->setup &&
> - newcon->setup(newcon, c->options) != 0)
> - break;
> - }
> + if (newcon->setup &&
> + newcon->setup(newcon, c->options) != 0)
> + break;
>
> newcon->flags |= CON_ENABLED;
> - if (i == preferred_console) {
> - newcon->flags |= CON_CONSDEV;
> - has_preferred = true;
> - }
> break;
> }
>
> if (!(newcon->flags & CON_ENABLED))
> return;
>
We could use a comment right about here, explaining why the below is
needed.
-- Steve
> + if (preferred_console >= 0 &&
> + match_console(newcon, console_cmdline + preferred_console) == 0) {
> + newcon->flags |= CON_CONSDEV;
> + has_preferred = true;
> + }
> +
> /*
> * If we have a bootconsole, and are switching to a real console,
> * don't print everything out again, since when the boot console, and
