On Thu, 02 Jun 2022 11:00:38 +0200, Michael Walle wrote: > If the earlycon parameter is given twice, the kernel will spit out a > WARN() in register_console() because it was already registered. The > non-dt variant setup_earlycon() already handles that gracefully. The dt > variant of_setup_earlycon() doesn't. Add the check there and add the > -EALREADY handling in early_init_dt_scan_chosen_stdout(). > > FWIW, this doesn't happen if CONFIG_ACPI_SPCR_TABLE is set. In that case > the registration is delayed until after earlycon parameter(s) are > parsed. > > Signed-off-by: Michael Walle <michael@xxxxxxxx> > --- > changes since v1: > - add missing EALREADY handling in of_setup_earlycon() > - return 0 early as suggested by Rob > > For the curious, here is the backtrace: > > [ 0.000000] ------------[ cut here ]------------ > [ 0.000000] WARNING: CPU: 0 PID: 0 at kernel/printk/printk.c:3328 register_console+0x2b4/0x364 > [ 0.000000] console 'atmel_serial0' already registered > [ 0.000000] Modules linked in: > [ 0.000000] CPU: 0 PID: 0 Comm: swapper Not tainted 5.18.0-next-20220601+ #652 > [ 0.000000] Hardware name: Generic DT based system > [ 0.000000] Backtrace: > [ 0.000000] dump_backtrace from show_stack+0x18/0x1c > [ 0.000000] show_stack from dump_stack_lvl+0x48/0x54 > [ 0.000000] dump_stack_lvl from dump_stack+0x18/0x1c > [ 0.000000] dump_stack from __warn+0xd0/0x148 > [ 0.000000] __warn from warn_slowpath_fmt+0x9c/0xc4 > [ 0.000000] warn_slowpath_fmt from register_console+0x2b4/0x364 > [ 0.000000] register_console from of_setup_earlycon+0x29c/0x2ac > [ 0.000000] of_setup_earlycon from early_init_dt_scan_chosen_stdout+0x154/0x18c > [ 0.000000] early_init_dt_scan_chosen_stdout from param_setup_earlycon+0x40/0x48 > [ 0.000000] param_setup_earlycon from do_early_param+0x88/0xc4 > [ 0.000000] do_early_param from parse_args+0x1a4/0x404 > [ 0.000000] parse_args from parse_early_options+0x40/0x48 > [ 0.000000] parse_early_options from parse_early_param+0x38/0x48 > [ 0.000000] parse_early_param from setup_arch+0x114/0x7a4 > [ 0.000000] setup_arch from start_kernel+0x74/0x6dc > [ 0.000000] start_kernel from 0x0 > [ 0.000000] ---[ end trace 0000000000000000 ]--- > > drivers/of/fdt.c | 4 +++- > drivers/tty/serial/earlycon.c | 3 +++ > 2 files changed, 6 insertions(+), 1 deletion(-) > Reviewed-by: Rob Herring <robh@xxxxxxxxxx>
