Commit 26214e32 authored by Andrew Morton's avatar Andrew Morton Committed by Linus Torvalds

[PATCH] ppc64: Fix CPU hot unplug deadlock

From: Benjamin Herrenschmidt <benh@kernel.crashing.org>

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)
parent f5e277c5
...@@ -504,9 +504,9 @@ asmlinkage int ppc_rtas(struct rtas_args __user *uargs) ...@@ -504,9 +504,9 @@ asmlinkage int ppc_rtas(struct rtas_args __user *uargs)
void rtas_stop_self(void) void rtas_stop_self(void)
{ {
struct rtas_args *rtas_args = &(get_paca()->xRtas); 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"); rtas_args->token = rtas_token("stop-self");
BUG_ON(rtas_args->token == RTAS_UNKNOWN_SERVICE); BUG_ON(rtas_args->token == RTAS_UNKNOWN_SERVICE);
rtas_args->nargs = 0; rtas_args->nargs = 0;
...@@ -516,7 +516,6 @@ void rtas_stop_self(void) ...@@ -516,7 +516,6 @@ void rtas_stop_self(void)
printk("%u %u Ready to die...\n", printk("%u %u Ready to die...\n",
smp_processor_id(), hard_smp_processor_id()); smp_processor_id(), hard_smp_processor_id());
enter_rtas((void *)__pa(rtas_args)); enter_rtas((void *)__pa(rtas_args));
spin_unlock_irqrestore(&rtas.lock, s);
panic("Alas, I survived.\n"); panic("Alas, I survived.\n");
} }
......
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