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powerpc: Move checks in pseries_mach_cpu_die() 

Rearrange condition checks for better code readability and
	prevention of possible race conditions when
	preferred_offline_state can potentially change during the
	execution of pseries_mach_cpu_die().  The patch will make
	pseries_mach_cpu_die() put cpu in one of the consistent states
	and not hit the run over BUG()

Signed-off-by: Vaidyanathan Srinivasan <svaidy@linux.vnet.ibm.com>
Cc: Gautham R Shenoy <ego@in.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
This commit is contained in:
Vaidyanathan Srinivasan 2010-03-01 02:58:16 +00:00 committed by Benjamin Herrenschmidt
parent 8dbce53cc2
commit 0212f2602a
1 changed files with 16 additions and 16 deletions
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32
arch/powerpc/platforms/pseries/hotplug-cpu.c
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@ -140,25 +140,25 @@ static void pseries_mach_cpu_die(void)
if (!get_lppaca()->shared_proc) if (!get_lppaca()->shared_proc)
get_lppaca()->donate_dedicated_cpu = 0; get_lppaca()->donate_dedicated_cpu = 0;
get_lppaca()->idle = 0; get_lppaca()->idle = 0;
if (get_preferred_offline_state(cpu) == CPU_STATE_ONLINE) {
unregister_slb_shadow(hwcpu, __pa(get_slb_shadow()));
/*
* Call to start_secondary_resume() will not return.
* Kernel stack will be reset and start_secondary()
* will be called to continue the online operation.
*/
start_secondary_resume();
}
} }
if (get_preferred_offline_state(cpu) == CPU_STATE_ONLINE) { /* Requested state is CPU_STATE_OFFLINE at this point */
unregister_slb_shadow(hwcpu, __pa(get_slb_shadow())); WARN_ON(get_preferred_offline_state(cpu) != CPU_STATE_OFFLINE);
/* set_cpu_current_state(cpu, CPU_STATE_OFFLINE);
* Call to start_secondary_resume() will not return. unregister_slb_shadow(hwcpu, __pa(get_slb_shadow()));
* Kernel stack will be reset and start_secondary() rtas_stop_self();
* will be called to continue the online operation.
*/
start_secondary_resume();
} else if (get_preferred_offline_state(cpu) == CPU_STATE_OFFLINE) {
set_cpu_current_state(cpu, CPU_STATE_OFFLINE);
unregister_slb_shadow(hard_smp_processor_id(),
__pa(get_slb_shadow()));
rtas_stop_self();
}
/* Should never get here... */ /* Should never get here... */
BUG(); BUG();