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Subject[PATCH] avr32: init cannot ignore signals sent by force_sig_info()
Date
From: Matt Fleming <matt.fleming@linux.intel.com>

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>
---
arch/avr32/kernel/traps.c | 22 ----------------------
1 files changed, 0 insertions(+), 22 deletions(-)

diff --git a/arch/avr32/kernel/traps.c b/arch/avr32/kernel/traps.c
index b91b204..7aa2575 100644
--- 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)
--
1.7.4


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