* [PATCH v2] earlycon: prevent multiple register_console()
@ 2022-06-02 9:00 Michael Walle
2022-06-02 14:29 ` Rob Herring
2022-06-28 11:21 ` Michael Walle
0 siblings, 2 replies; 4+ messages in thread
From: Michael Walle @ 2022-06-02 9:00 UTC (permalink / raw)
To: Rob Herring, Frank Rowand, Greg Kroah-Hartman, Jiri Slaby
Cc: devicetree, linux-kernel, linux-serial, Michael Walle
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@walle.cc>
---
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(-)
diff --git a/drivers/of/fdt.c b/drivers/of/fdt.c
index a8f5b6532165..043b12be22d6 100644
--- a/drivers/of/fdt.c
+++ b/drivers/of/fdt.c
@@ -1025,6 +1025,7 @@ int __init early_init_dt_scan_chosen_stdout(void)
int l;
const struct earlycon_id *match;
const void *fdt = initial_boot_params;
+ int ret;
offset = fdt_path_offset(fdt, "/chosen");
if (offset < 0)
@@ -1057,7 +1058,8 @@ int __init early_init_dt_scan_chosen_stdout(void)
if (fdt_node_check_compatible(fdt, offset, match->compatible))
continue;
- if (of_setup_earlycon(match, offset, options) == 0)
+ ret = of_setup_earlycon(match, offset, options);
+ if (!ret || ret == -EALREADY)
return 0;
}
return -ENODEV;
diff --git a/drivers/tty/serial/earlycon.c b/drivers/tty/serial/earlycon.c
index 57c70851f22a..88d08ba1ca83 100644
--- a/drivers/tty/serial/earlycon.c
+++ b/drivers/tty/serial/earlycon.c
@@ -253,6 +253,9 @@ int __init of_setup_earlycon(const struct earlycon_id *match,
bool big_endian;
u64 addr;
+ if (early_con.flags & CON_ENABLED)
+ return -EALREADY;
+
spin_lock_init(&port->lock);
port->iotype = UPIO_MEM;
addr = of_flat_dt_translate_address(node);
--
2.30.2
^ permalink raw reply related [flat|nested] 4+ messages in thread
* Re: [PATCH v2] earlycon: prevent multiple register_console()
2022-06-02 9:00 [PATCH v2] earlycon: prevent multiple register_console() Michael Walle
@ 2022-06-02 14:29 ` Rob Herring
2022-06-28 11:21 ` Michael Walle
1 sibling, 0 replies; 4+ messages in thread
From: Rob Herring @ 2022-06-02 14:29 UTC (permalink / raw)
To: Michael Walle
Cc: Frank Rowand, linux-serial, Jiri Slaby, Greg Kroah-Hartman,
linux-kernel, Rob Herring, devicetree
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@walle.cc>
> ---
> 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@kernel.org>
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH v2] earlycon: prevent multiple register_console()
2022-06-02 9:00 [PATCH v2] earlycon: prevent multiple register_console() Michael Walle
2022-06-02 14:29 ` Rob Herring
@ 2022-06-28 11:21 ` Michael Walle
2022-06-28 11:55 ` Greg Kroah-Hartman
1 sibling, 1 reply; 4+ messages in thread
From: Michael Walle @ 2022-06-28 11:21 UTC (permalink / raw)
To: Rob Herring, Frank Rowand, Greg Kroah-Hartman, Jiri Slaby
Cc: devicetree, linux-kernel, linux-serial
Hi,
Am 2022-06-02 11:00, schrieb Michael Walle:
> 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@walle.cc>
Ping :) Or do I have to resend this patch?
-michael
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH v2] earlycon: prevent multiple register_console()
2022-06-28 11:21 ` Michael Walle
@ 2022-06-28 11:55 ` Greg Kroah-Hartman
0 siblings, 0 replies; 4+ messages in thread
From: Greg Kroah-Hartman @ 2022-06-28 11:55 UTC (permalink / raw)
To: Michael Walle
Cc: Rob Herring, Frank Rowand, Jiri Slaby, devicetree, linux-kernel,
linux-serial
On Tue, Jun 28, 2022 at 01:21:23PM +0200, Michael Walle wrote:
> Hi,
>
> Am 2022-06-02 11:00, schrieb Michael Walle:
> > 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@walle.cc>
>
> Ping :) Or do I have to resend this patch?
I do not see it in my queue anywhere.
^ permalink raw reply [flat|nested] 4+ messages in thread
end of thread, other threads:[~2022-06-28 11:55 UTC | newest]
Thread overview: 4+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2022-06-02 9:00 [PATCH v2] earlycon: prevent multiple register_console() Michael Walle
2022-06-02 14:29 ` Rob Herring
2022-06-28 11:21 ` Michael Walle
2022-06-28 11:55 ` Greg Kroah-Hartman
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