On Thu, May 26, 2011 at 7:12 PM, K.Prasad <prasad at linux.vnet.ibm.com> wrote:
>
> commit e668fa1aea7844ac4c7ea09030a2f3e647a4adb1
> Author: Andi Kleen <ak at linux.intel.com>
> Date: ? Fri Nov 19 18:36:44 2010 +0100
>
> ? ?XPANIC: Add extended panic interface
>
> ? ?One panic size doesn't fit all.
>
> ? ?Machine check has some special requirements on panic, like:
> ? ?- It wants to do a reboot timeout by default so that the machine
> ? ?check event can be logged to disk after warm reboot.
> ? ?- For memory errors it usually doesn't want to do crash dumps because
> ? ?that can lead to crash loops (dumping corrupted memory would
> ? ?lead to another machine check)
> ? ?- It doesn't want to do backtraces because machine checks
> ? ?are not a kernel bug.
>
> ? ?In a earlier patch this was done with various adhoc hacks,
> ? ?but it's cleaner to extend panic to a 'xpanic' that directly
> ? ?gets a flag and timeout argument.
>
> ? ?The only user right now will be x86 machine checks, but I consider
> ? ?it likely that other users will switch to this too.
>
> ? ?For example one obvious candidate would be the "no root
> ? ?found" panic which doesn't really deserve a backtrace.
>
> ? ?I exported a vpanic() interface too as a global. That's not
> ? ?needed by the current user, but the interface has to exist
> ? ?internally anyways and I could see how other code would
> ? ?find a v* variant of panic useful.
>
> ? ?Originally based on a suggestion by H. Peter Anvin.
> ? ?Signed-off-by: Andi Kleen <ak at linux.intel.com>
>
> ---
> ?include/linux/kernel.h | ? 11 +++++++++++
> ?kernel/panic.c ? ? ? ? | ? 41 +++++++++++++++++++++++++++++++----------
> ?2 files changed, 42 insertions(+), 10 deletions(-)
>
> Index: linux-2.6.slim_kdump/include/linux/kernel.h
> ===================================================================
> --- linux-2.6.slim_kdump.orig/include/linux/kernel.h
> +++ linux-2.6.slim_kdump/include/linux/kernel.h
> @@ -175,10 +175,21 @@ static inline void might_fault(void)
> ?}
> ?#endif
>
> +enum panic_flags {
> + ? ? ? PANIC_NO_KEXEC ? ? = (1 << 0),
> + ? ? ? PANIC_NO_BACKTRACE = (1 << 1),
> +};
> +
> ?extern struct atomic_notifier_head panic_notifier_list;
> ?extern long (*panic_blink)(int state);
> ?NORET_TYPE void panic(const char * fmt, ...)
> ? ? ? ?__attribute__ ((NORET_AND format (printf, 1, 2))) __cold;
> +NORET_TYPE void xpanic(enum panic_flags flags, int timeout,
> + ? ? ? ? ? ? ? ? ? ? ?const char *fmt, ...)
> + ? ? ? __attribute__ ((NORET_AND format (printf, 3, 4))) __cold;
> +NORET_TYPE void vpanic(enum panic_flags flags, int timeout,
> + ? ? ? ? ? ? ? ? ? ? ?const char *fmt,
> + ? ? ? ? ? ? ? ? ? ? ?va_list ap) __noreturn __cold;
> ?extern void oops_enter(void);
> ?extern void oops_exit(void);
> ?void print_oops_end_marker(void);
> Index: linux-2.6.slim_kdump/kernel/panic.c
> ===================================================================
> --- linux-2.6.slim_kdump.orig/kernel/panic.c
> +++ linux-2.6.slim_kdump/kernel/panic.c
> @@ -57,14 +57,37 @@ EXPORT_SYMBOL(panic_blink);
> ?*
> ?* ? ? This function never returns.
> ?*/
> -NORET_TYPE void panic(const char * fmt, ...)
> +NORET_TYPE void panic(const char *fmt, ...)
> +{
> + ? ? ? va_list ap;
> + ? ? ? va_start(ap, fmt);
> + ? ? ? vpanic(0, 0, fmt, ap);
> +}
> +EXPORT_SYMBOL(panic);
> +
> +NORET_TYPE void xpanic(enum panic_flags flags, int timeout,
> + ? ? ? ? ? ? ? ? ? ? ? const char *fmt, ...)
> +{
> + ? ? ? va_list ap;
> + ? ? ? va_start(ap, fmt);
> + ? ? ? xpanic(flags, timeout, fmt, ap);
Why are you calling xpanic() here again?
I guess you meant vpanic().
> +}
> +EXPORT_SYMBOL(xpanic);
> +
> +NORET_TYPE void vpanic(enum panic_flags flags, int timeout,
> + ? ? ? ? ? ? ? ? ? ? ?const char * fmt, va_list args)
> ?{
> ? ? ? ?static char buf[1024];
> - ? ? ? va_list args;
> ? ? ? ?long i, i_next = 0;
> ? ? ? ?int state = 0;
>
> ? ? ? ?/*
> + ? ? ? ?* Let user always override panic_timeout.
> + ? ? ? ?*/
> + ? ? ? if (panic_timeout > 0)
> + ? ? ? ? ? ? ? timeout = panic_timeout;
> +
> + ? ? ? /*
> ? ? ? ? * It's possible to come here directly from a panic-assertion and
> ? ? ? ? * not have preempt disabled. Some functions called from here want
> ? ? ? ? * preempt to be disabled. No point enabling it later though...
> @@ -73,12 +96,11 @@ NORET_TYPE void panic(const char * fmt,
>
> ? ? ? ?console_verbose();
> ? ? ? ?bust_spinlocks(1);
> - ? ? ? va_start(args, fmt);
> ? ? ? ?vsnprintf(buf, sizeof(buf), fmt, args);
> - ? ? ? va_end(args);
> ? ? ? ?printk(KERN_EMERG "Kernel panic - not syncing: %s\n",buf);
> ?#ifdef CONFIG_DEBUG_BUGVERBOSE
> - ? ? ? dump_stack();
> + ? ? ? if (!(flags & PANIC_NO_BACKTRACE))
> + ? ? ? ? ? ? ? dump_stack();
> ?#endif
>
> ? ? ? ?/*
> @@ -86,7 +108,8 @@ NORET_TYPE void panic(const char * fmt,
> ? ? ? ? * everything else.
> ? ? ? ? * Do we want to call this before we try to display a message?
> ? ? ? ? */
> - ? ? ? crash_kexec(NULL);
> + ? ? ? if (!(flags & PANIC_NO_KEXEC))
> + ? ? ? ? ? ? ? crash_kexec(NULL);
>
> ? ? ? ?kmsg_dump(KMSG_DUMP_PANIC);
>
> @@ -104,7 +127,7 @@ NORET_TYPE void panic(const char * fmt,
> ? ? ? ?if (!panic_blink)
> ? ? ? ? ? ? ? ?panic_blink = no_blink;
>
> - ? ? ? if (panic_timeout > 0) {
> + ? ? ? if (timeout > 0) {
> ? ? ? ? ? ? ? ?/*
> ? ? ? ? ? ? ? ? * Delay timeout seconds before rebooting the machine.
> ? ? ? ? ? ? ? ? * We can't use the "normal" timers since we just panicked.
> @@ -152,9 +175,7 @@ NORET_TYPE void panic(const char * fmt,
> ? ? ? ? ? ? ? ?mdelay(PANIC_TIMER_STEP);
> ? ? ? ?}
> ?}
> -
> -EXPORT_SYMBOL(panic);
> -
> +EXPORT_SYMBOL(vpanic);
>
> ?struct tnt {
> ? ? ? ?u8 ? ? ?bit;
> --
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--
Thanks,
//richard
