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OpenCloudOS-Kernel
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x86, UV: Fix smp_processor_id() use in a preemptable region 

Fix a call by tunables_write() to smp_processor_id() within a
preemptable region.

Call get_cpu()/put_cpu() around the region where the returned
cpu number is actually used, which makes it non-preemptable.

A DEBUG_PREEMPT warning is prevented.

UV does not support cpu hotplug yet, but this is a step toward
that ability as well.

Signed-off-by: Cliff Wickman <cpw@sgi.com>
Link: http://lkml.kernel.org/r/20110621122242.086384966@sgi.com
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
cpw@sgi.com 2011-06-21 07:21:26 -05:00 committed by Ingo Molnar
parent 6885685923
commit 00b30cf04a
1 changed files with 3 additions and 2 deletions
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5
arch/x86/platform/uv/tlb_uv.c
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@ -1334,9 +1334,10 @@ static ssize_t tunables_write(struct file *file, const char __user *user,
instr[count] = '\0';
bcp = &per_cpu(bau_control, smp_processor_id());
cpu = get_cpu();
bcp = &per_cpu(bau_control, cpu);
ret = parse_tunables_write(bcp, instr, count);
put_cpu();
if (ret)
return ret;