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x86: improve UP kernel when CPU-hotplug and SMP is enabled 

num_possible_cpus() can be > 1 when disabled CPUs have been accounted.

Disabled CPUs are not in the cpu_present_map, so we can use
num_present_cpus() as a safe indicator to switch to UP alternatives.

Reported-by: Chuck Ebbert <cebbert@redhat.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: <stable@kernel.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Thomas Gleixner 2008-10-05 16:52:24 +02:00 committed by Ingo Molnar
parent 8a541665b9
commit 649c6653fa
1 changed files with 1 additions and 1 deletions
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2
arch/x86/kernel/alternative.c
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@ -444,7 +444,7 @@ void __init alternative_instructions(void)
_text, _etext);
/* Only switch to UP mode if we don't immediately boot others */
if (num_possible_cpus() == 1 || setup_max_cpus <= 1)
if (num_present_cpus() == 1 || setup_max_cpus <= 1)
alternatives_smp_switch(0);
}
#endif