[PATCH 12/15] misc: Configurable panic support

Matt Mackall
2005-11-11T08:37:34Z

Configurable no-op of panic()

Similar to disabling printk and BUG_ON, this allows completely
removing the panic infrastructure for systems where it isn't useful.

text data bss dec hex
3330172 529036 190556 4049764 3dcb64 baseline
3324560 529016 189532 4043108 3db164 no-panic

Index: 2.6.14-misc/init/Kconfig
===================================================================
--- 2.6.14-misc.orig/init/Kconfig 2005-11-09 16:48:24.000000000 -0800
+++ 2.6.14-misc/init/Kconfig 2005-11-09 16:50:44.000000000 -0800
@@ -324,7 +324,16 @@ config DOUBLEFAULT
would otherwise cause a system to silently reboot. Disabling this
option saves about 4k.

+config PANIC
+ default y
+ bool "Enable panic reporting code" if EMBEDDED
+ help
+ Disabling this completely removes panic handling code.
+ Warning: this can result in data loss if a panic condition
+ occurs, as the kernel may ignore the condition entirely.
+
config FULL_PANIC
+ depends PANIC
default y
bool "Full panic reporting data" if EMBEDDED
help
Index: 2.6.14-misc/init/main.c
===================================================================
--- 2.6.14-misc.orig/init/main.c 2005-11-09 16:48:24.000000000 -0800
+++ 2.6.14-misc/init/main.c 2005-11-09 16:50:44.000000000 -0800
@@ -742,4 +742,5 @@ static int init(void * unused)
run_init_process("/bin/sh");

panic("No init found. Try passing init= option to kernel.");
+ return 0;
}
Index: 2.6.14-misc/kernel/panic.c
===================================================================
--- 2.6.14-misc.orig/kernel/panic.c 2005-11-09 16:50:29.000000000 -0800
+++ 2.6.14-misc/kernel/panic.c 2005-11-09 16:50:55.000000000 -0800
@@ -37,15 +37,16 @@ static int __init panic_setup(char *str)
}
__setup("panic=", panic_setup);

+/* Returns how long it waited in ms */
+long (*panic_blink)(long time);
+EXPORT_SYMBOL(panic_blink);
+
+#ifdef CONFIG_PANIC
static long no_blink(long time)
{
return 0;
}

-/* Returns how long it waited in ms */
-long (*panic_blink)(long time);
-EXPORT_SYMBOL(panic_blink);
-
/**
* panic - halt the system
* @fmt: The text string to print
@@ -157,6 +158,7 @@ EXPORT_SYMBOL(panic);
#else
EXPORT_SYMBOL(tiny_panic);
#endif
+#endif

/**
* print_tainted - return a string to represent the kernel taint state.
Index: 2.6.14-misc/include/linux/kernel.h
===================================================================
--- 2.6.14-misc.orig/include/linux/kernel.h 2005-11-09 16:48:24.000000000 -0800
+++ 2.6.14-misc/include/linux/kernel.h 2005-11-09 16:50:44.000000000 -0800
@@ -87,6 +87,11 @@ extern int cond_resched(void);

extern struct notifier_block *panic_notifier_list;
extern long (*panic_blink)(long time);
+#ifndef CONFIG_PANIC
+NORET_TYPE static inline void panic(const char * fmt, ...)
+ __attribute__ ((NORET_AND format (printf, 1, 2)));
+NORET_TYPE static inline void panic(const char * fmt, ...) {}
+#else
#ifdef CONFIG_FULL_PANIC
NORET_TYPE void panic(const char * fmt, ...)
__attribute__ ((NORET_AND format (printf, 1, 2)));
@@ -94,6 +99,7 @@ NORET_TYPE void panic(const char * fmt,
#define panic(fmt, ...) tiny_panic(0, ## __VA_ARGS__)
NORET_TYPE void tiny_panic(int a, ...) ATTRIB_NORET;
#endif
+#endif
fastcall NORET_TYPE void do_exit(long error_code)
ATTRIB_NORET;
NORET_TYPE void complete_and_exit(struct completion *, long)