Commit 9f0d15aa authored Apr 04, 2011 by Matt Fleming Committed by Hans-Christian Egtvedt Apr 13, 2011

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

623b0355 "[AVR32] Clean up exception handling code"

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

a0592d42 "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>

parent 6e2ad511

arch/avr32/kernel/traps.c

+0 −22

Original line number	Original line	Diff line number	Diff line
	@@ -95,28 +95,6 @@ void _exception(long signr, struct pt_regs *regs, int code,
	info.si_code = code;		info.si_code = code;
	info.si_addr = (void __user *)addr;		info.si_addr = (void __user *)addr;
	force_sig_info(signr, &info, current);		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)		asmlinkage void do_nmi(unsigned long ecr, struct pt_regs *regs)