avr32: init cannot ignore signals sent by force_sig_info()

We can delete the code that checks to see if we're sending an ignored
signal to init because force_sig_info() already handles this case.
force_sig_info() will kill init even if the signal handler is SIG_DFL
and the scenario described in the comment where init might "generate
the same exception over and over again" cannot occur (force_sig_info()
clears SIGNAL_UNKILLABLE to ensure that init will die).

Also, the use of is_global_init() is not correct in the multhreaded
case, as Oleg Nesterov explains,

	"is_global_init() is not right in theory, /sbin/init can be
	multithreaded. And, this doesn't cover the sub-namespace
	inits... I'd suggest to check SIGNAL_UNKILLABLE, but looking
	closer I think you can simply remove this code."

It seems this code was copied from arch/powerpc in March 2007 in commit

  623b0355d5b1 "[AVR32] Clean up exception handling code"

but the code was deleted from arch/powerpc in November 2009 in commit

  a0592d42fe3e "powerpc: kill the obsolete code under is_global_init()"

So catch up with powerpc and delete the bogus code.

Signed-off-by: Matt Fleming <matt.fleming@linux.intel.com>
Signed-off-by: Hans-Christian Egtvedt <hans-christian.egtvedt@atmel.com>

diff --git a/arch/avr32/kernel/traps.c b/arch/avr32/kernel/traps.c
index b91b204..7aa2575 100644 (file)
--- a/arch/avr32/kernel/traps.c
+++ b/arch/avr32/kernel/traps.c
@@ -95,28 +95,6 @@ void _exception(long signr, struct pt_regs *regs, int code,
        info.si_code = code;
        info.si_addr = (void __user *)addr;
        force_sig_info(signr, &info, current);
-
-       /*
-        * Init gets no signals that it doesn't have a handler for.
-        * That's all very well, but if it has caused a synchronous
-        * exception and we ignore the resulting signal, it will just
-        * generate the same exception over and over again and we get
-        * nowhere.  Better to kill it and let the kernel panic.
-        */
-       if (is_global_init(current)) {
-               __sighandler_t handler;
-
-               spin_lock_irq(&current->sighand->siglock);
-               handler = current->sighand->action[signr-1].sa.sa_handler;
-               spin_unlock_irq(&current->sighand->siglock);
-               if (handler == SIG_DFL) {
-                       /* init has generated a synchronous exception
-                          and it doesn't have a handler for the signal */
-                       printk(KERN_CRIT "init has generated signal %ld "
-                              "but has no handler for it\n", signr);
-                       do_exit(signr);
-               }
-       }
 }
 
 asmlinkage void do_nmi(unsigned long ecr, struct pt_regs *regs)