[PATCH] ppc64: Fix CPU hot unplug deadlock

[Benjamin Herrenschmidt]

Hi !

My RTAS locking fixes incorrectly added a spinlock around the function
used to stop a CPU, that function never returns, thus the lock becomes
stale. The correct fix is to disable interrupts instead (the RTAS params
beeing per-CPU, this should be safe enough)

Ben.

diff -urN linux-2.5/arch/ppc64/kernel/rtas.c ppc64-linux-2.5/arch/ppc64/kernel/rtas.c
--- linux-2.5/arch/ppc64/kernel/rtas.c	2004-04-17 12:39:03.253986984 +1000
+++ ppc64-linux-2.5/arch/ppc64/kernel/rtas.c	2004-04-18 15:35:41.871029480 +1000
@@ -504,9 +504,9 @@
 void rtas_stop_self(void)
 {
 	struct rtas_args *rtas_args = &(get_paca()->xRtas);
-	unsigned long s;
 
-	spin_lock_irqsave(&rtas.lock, s);
+	local_irq_disable(s);
+
 	rtas_args->token = rtas_token("stop-self");
 	BUG_ON(rtas_args->token == RTAS_UNKNOWN_SERVICE);
 	rtas_args->nargs = 0;
@@ -516,7 +516,6 @@
 	printk("%u %u Ready to die...\n",
 	       smp_processor_id(), hard_smp_processor_id());
 	enter_rtas((void *)__pa(rtas_args));
-	spin_unlock_irqrestore(&rtas.lock, s);
 
 	panic("Alas, I survived.\n");
 }


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