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Subject[PATCH/RFC] m68k/amiga: Fix specifying multiple debug= parameters
Date
Since commit d6713b4091a99fa2af2fabdcd2f3fb97f32ecf2e ("m68k: early
parameter support"), the user can specify multiple debug consoles using the
"debug=" kernel command line parameter.
However, as the struct console object was shared, it would actually register
the same console object multiple times, causing the following warning:

WARNING: CPU: 0 PID: 0 at kernel/printk/printk.c:2233 register_console+0x36/0x2b6()
console 'debug0' already registered

Note that only the console corresponding to the last "debug=" parameter became
active, as the .write() method was overwritten before registration.

Use separate console objects to allow using multiple debug consoles.

Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
---
Notes:
1. This patch was only compile-tested.
2. Do we want to fix it this way? Alternatives are:
a. Reject a second debug= parameter by checking for a non-NULL .write()
method
=> only the first debug console will be used,
b. Skip console registration in case of a non-NULL .write() method
=> only the last debug console will be used,
3. Atari has a similar issue, with even more (4) debug consoles.

arch/m68k/amiga/config.c | 26 ++++++++++++++++----------
1 file changed, 16 insertions(+), 10 deletions(-)

diff --git a/arch/m68k/amiga/config.c b/arch/m68k/amiga/config.c
index 049ef8605314..b975eefba30f 100644
--- a/arch/m68k/amiga/config.c
+++ b/arch/m68k/amiga/config.c
@@ -107,12 +107,6 @@ static void amiga_mem_console_write(struct console *co, const char *b,
static void amiga_heartbeat(int on);
#endif

-static struct console amiga_console_driver = {
- .name = "debug",
- .flags = CON_PRINTBUFFER,
- .index = -1,
-};
-

/*
* Motherboard Resources present in all Amiga models
@@ -624,6 +618,13 @@ static void amiga_mem_console_write(struct console *co, const char *s,
}
}

+static struct console amiga_mem_console = {
+ .name = "debug",
+ .write = amiga_mem_console_write,
+ .flags = CON_PRINTBUFFER,
+ .index = -1,
+};
+
static int __init amiga_savekmsg_setup(char *arg)
{
if (!MACH_IS_AMIGA || strcmp(arg, "mem"))
@@ -642,8 +643,7 @@ static int __init amiga_savekmsg_setup(char *arg)
savekmsg->magicptr = ZTWO_PADDR(savekmsg);
savekmsg->size = 0;

- amiga_console_driver.write = amiga_mem_console_write;
- register_console(&amiga_console_driver);
+ register_console(&amiga_mem_console);
return 0;
}

@@ -723,12 +723,18 @@ void amiga_serial_gets(struct console *co, char *s, int len)
}
#endif

+static struct console amiga_serial_console = {
+ .name = "debug",
+ .write = amiga_serial_console_write,
+ .flags = CON_PRINTBUFFER,
+ .index = -1,
+};
+
static int __init amiga_debug_setup(char *arg)
{
if (MACH_IS_AMIGA && !strcmp(arg, "ser")) {
/* no initialization required (?) */
- amiga_console_driver.write = amiga_serial_console_write;
- register_console(&amiga_console_driver);
+ register_console(&amiga_serial_console);
}
return 0;
}
--
1.7.9.5


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