[RFC PATCH 0/5] earlycon hang under some conditions

[RFC PATCH 0/5] earlycon hang under some conditions

[Jeffy Chen]

I was testing earlycon with 8250 dw serial console. And it hangs in
these cases:
1/ kernel hang when calling early write function after free_initmem:
a) the earlycon not disabled after the init code(due to keep_bootcon or
   not specify a real console to switch to)
b) the early write func is marked as __init, for example 8250_early.

2/ kernel hang when calling early write function after disable unused
clks/pm domain:
a) the earlycon not disabled after the init code
b) the disable unused clks/pm domain kill the requiered clks/pm
   domain, since they are not referenced by the earlycon.

3/ kernel hang when calling early write function after the serial
   console driver runtime suspended:
a) the earlycon not disabled after the init code
b) the serial console driver's runtime suspend kills the requiered
   clks/pm domain, since they are not referenced by the earlycon.

This serial fix 1/ case only.



Jeffy Chen (5):
  serial: arc: Remove __init marking from early write
  serial: omap: Remove __init marking from early write
  serial: xuartps: Remove __init marking from early write
  serial: 8250_ingenic: Remove __init marking from early write
  serial: 8250_early: Remove __init marking from early write

 drivers/tty/serial/8250/8250_early.c   |  8 ++++----
 drivers/tty/serial/8250/8250_ingenic.c |  8 ++++----
 drivers/tty/serial/arc_uart.c          |  4 ++--
 drivers/tty/serial/omap-serial.c       | 13 ++++++-------
 drivers/tty/serial/xilinx_uartps.c     |  2 +-
 5 files changed, 17 insertions(+), 18 deletions(-)

-- 
2.1.4

[RFC PATCH 1/5] serial: arc: Remove __init marking from early write

[Jeffy Chen]

The earlycon would be alive outside the init code in these cases:
1/ we have keep_bootcon in cmdline.
2/ we don't have a real console to switch to.

So remove the __init marking to avoid invalid memory access.

Signed-off-by: Jeffy Chen <jeffy.chen@rock-chips.com>
---

 drivers/tty/serial/arc_uart.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/tty/serial/arc_uart.c b/drivers/tty/serial/arc_uart.c
index 5ac06fc..77fe306 100644
--- a/drivers/tty/serial/arc_uart.c
+++ b/drivers/tty/serial/arc_uart.c
@@ -549,8 +549,8 @@ static struct console arc_console = {
 	.data	= &arc_uart_driver
 };
 
-static __init void arc_early_serial_write(struct console *con, const char *s,
-					  unsigned int n)
+static void arc_early_serial_write(struct console *con, const char *s,
+				   unsigned int n)
 {
 	struct earlycon_device *dev = con->data;
 
-- 
2.1.4

[RFC PATCH 2/5] serial: omap: Remove __init marking from early write

[Jeffy Chen]

The earlycon would be alive outside the init code in these cases:
1/ we have keep_bootcon in cmdline.
2/ we don't have a real console to switch to.

So remove the __init marking to avoid invalid memory access.

Signed-off-by: Jeffy Chen <jeffy.chen@rock-chips.com>
---

 drivers/tty/serial/omap-serial.c | 13 ++++++-------
 1 file changed, 6 insertions(+), 7 deletions(-)

diff --git a/drivers/tty/serial/omap-serial.c b/drivers/tty/serial/omap-serial.c
index 1ea05ac..7754053 100644
--- a/drivers/tty/serial/omap-serial.c
+++ b/drivers/tty/serial/omap-serial.c
@@ -1235,21 +1235,20 @@ static int serial_omap_poll_get_char(struct uart_port *port)
 #ifdef CONFIG_SERIAL_OMAP_CONSOLE
 
 #ifdef CONFIG_SERIAL_EARLYCON
-static unsigned int __init omap_serial_early_in(struct uart_port *port,
-						int offset)
+static unsigned int omap_serial_early_in(struct uart_port *port, int offset)
 {
 	offset <<= port->regshift;
 	return readw(port->membase + offset);
 }
 
-static void __init omap_serial_early_out(struct uart_port *port, int offset,
-					 int value)
+static void omap_serial_early_out(struct uart_port *port, int offset,
+				  int value)
 {
 	offset <<= port->regshift;
 	writew(value, port->membase + offset);
 }
 
-static void __init omap_serial_early_putc(struct uart_port *port, int c)
+static void omap_serial_early_putc(struct uart_port *port, int c)
 {
 	unsigned int status;
 
@@ -1262,8 +1261,8 @@ static void __init omap_serial_early_putc(struct uart_port *port, int c)
 	omap_serial_early_out(port, UART_TX, c);
 }
 
-static void __init early_omap_serial_write(struct console *console,
-					   const char *s, unsigned int count)
+static void early_omap_serial_write(struct console *console, const char *s,
+				    unsigned int count)
 {
 	struct earlycon_device *device = console->data;
 	struct uart_port *port = &device->port;
-- 
2.1.4

[RFC PATCH 3/5] serial: xuartps: Remove __init marking from early write

[Jeffy Chen]

The earlycon would be alive outside the init code in these cases:
1/ we have keep_bootcon in cmdline.
2/ we don't have a real console to switch to.

So remove the __init marking to avoid invalid memory access.

Signed-off-by: Jeffy Chen <jeffy.chen@rock-chips.com>
---

 drivers/tty/serial/xilinx_uartps.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/tty/serial/xilinx_uartps.c b/drivers/tty/serial/xilinx_uartps.c
index fde55dc..31a630a 100644
--- a/drivers/tty/serial/xilinx_uartps.c
+++ b/drivers/tty/serial/xilinx_uartps.c
@@ -1163,7 +1163,7 @@ static void cdns_uart_console_putchar(struct uart_port *port, int ch)
 	writel(ch, port->membase + CDNS_UART_FIFO);
 }
 
-static void __init cdns_early_write(struct console *con, const char *s,
+static void cdns_early_write(struct console *con, const char *s,
 				    unsigned n)
 {
 	struct earlycon_device *dev = con->data;
-- 
2.1.4

[RFC PATCH 4/5] serial: 8250_ingenic: Remove __init marking from early write

[Jeffy Chen]

The earlycon would be alive outside the init code in these cases:
1/ we have keep_bootcon in cmdline.
2/ we don't have a real console to switch to.

So remove the __init marking to avoid invalid memory access.

Signed-off-by: Jeffy Chen <jeffy.chen@rock-chips.com>
---

 drivers/tty/serial/8250/8250_ingenic.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/drivers/tty/serial/8250/8250_ingenic.c b/drivers/tty/serial/8250/8250_ingenic.c
index 4d9dc10..464389b 100644
--- a/drivers/tty/serial/8250/8250_ingenic.c
+++ b/drivers/tty/serial/8250/8250_ingenic.c
@@ -50,17 +50,17 @@ static const struct of_device_id of_match[];
 
 static struct earlycon_device *early_device;
 
-static uint8_t __init early_in(struct uart_port *port, int offset)
+static uint8_t early_in(struct uart_port *port, int offset)
 {
 	return readl(port->membase + (offset << 2));
 }
 
-static void __init early_out(struct uart_port *port, int offset, uint8_t value)
+static void early_out(struct uart_port *port, int offset, uint8_t value)
 {
 	writel(value, port->membase + (offset << 2));
 }
 
-static void __init ingenic_early_console_putc(struct uart_port *port, int c)
+static void ingenic_early_console_putc(struct uart_port *port, int c)
 {
 	uint8_t lsr;
 
@@ -71,7 +71,7 @@ static void __init ingenic_early_console_putc(struct uart_port *port, int c)
 	early_out(port, UART_TX, c);
 }
 
-static void __init ingenic_early_console_write(struct console *console,
+static void ingenic_early_console_write(struct console *console,
 					      const char *s, unsigned int count)
 {
 	uart_console_write(&early_device->port, s, count,
-- 
2.1.4

[RFC PATCH 5/5] serial: 8250_early: Remove __init marking from early write

[Jeffy Chen]

The earlycon would be alive outside the init code in these cases:
1/ we have keep_bootcon in cmdline.
2/ we don't have a real console to switch to.

So remove the __init marking to avoid invalid memory access.

Signed-off-by: Jeffy Chen <jeffy.chen@rock-chips.com>
---

 drivers/tty/serial/8250/8250_early.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/drivers/tty/serial/8250/8250_early.c b/drivers/tty/serial/8250/8250_early.c
index 82fc48e..af72ec3 100644
--- a/drivers/tty/serial/8250/8250_early.c
+++ b/drivers/tty/serial/8250/8250_early.c
@@ -37,7 +37,7 @@
 #include <asm/io.h>
 #include <asm/serial.h>
 
-static unsigned int __init serial8250_early_in(struct uart_port *port, int offset)
+static unsigned int serial8250_early_in(struct uart_port *port, int offset)
 {
 	int reg_offset = offset;
 	offset <<= port->regshift;
@@ -60,7 +60,7 @@ static unsigned int __init serial8250_early_in(struct uart_port *port, int offse
 	}
 }
 
-static void __init serial8250_early_out(struct uart_port *port, int offset, int value)
+static void serial8250_early_out(struct uart_port *port, int offset, int value)
 {
 	int reg_offset = offset;
 	offset <<= port->regshift;
@@ -89,7 +89,7 @@ static void __init serial8250_early_out(struct uart_port *port, int offset, int
 
 #define BOTH_EMPTY (UART_LSR_TEMT | UART_LSR_THRE)
 
-static void __init serial_putc(struct uart_port *port, int c)
+static void serial_putc(struct uart_port *port, int c)
 {
 	unsigned int status;
 
@@ -103,7 +103,7 @@ static void __init serial_putc(struct uart_port *port, int c)
 	}
 }
 
-static void __init early_serial8250_write(struct console *console,
+static void early_serial8250_write(struct console *console,
 					const char *s, unsigned int count)
 {
 	struct earlycon_device *device = console->data;
-- 
2.1.4

Re: [RFC PATCH 1/5] serial: arc: Remove __init marking from early write

[Greg KH]

On Tue, Jul 18, 2017 at 12:29:59PM +0800, Jeffy Chen wrote:
> The earlycon would be alive outside the init code in these cases:
> 1/ we have keep_bootcon in cmdline.
> 2/ we don't have a real console to switch to.
> 
> So remove the __init marking to avoid invalid memory access.
> 
> Signed-off-by: Jeffy Chen <jeffy.chen@rock-chips.com>
> ---
> 

I can't apply "RFC" patches.  If you have tested and found this series
to be correct, can you resend it without that on the patch?

thanks,

greg k-h

Re: [RFC PATCH 1/5] serial: arc: Remove __init marking from early write

[jeffy]

Hi Greg,

On 07/18/2017 01:08 PM, Greg KH wrote:
> On Tue, Jul 18, 2017 at 12:29:59PM +0800, Jeffy Chen wrote:
>> The earlycon would be alive outside the init code in these cases:
>> 1/ we have keep_bootcon in cmdline.
>> 2/ we don't have a real console to switch to.
>>
>> So remove the __init marking to avoid invalid memory access.
>>
>> Signed-off-by: Jeffy Chen <jeffy.chen@rock-chips.com>
>> ---
>>
>
> I can't apply "RFC" patches.  If you have tested and found this series
> to be correct, can you resend it without that on the patch?
oh, sorry, i'll resend it :)

but i'm still not sure how to fix other hang cases(mentioned in the 
cover-letter, earlycon's required clks/pm domain been disabled by ignore 
unused initcalls or serial console driver's runtime suspend).
>
> thanks,
>
> greg k-h
>
>
>