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smp: have smp_call_function_single() detect invalid CPUs 

Have smp_call_function_single() return invalid CPU indicies and return
-ENXIO.  This function is already executed inside a
get_cpu()..put_cpu() which locks out CPU removal, so rather than
having the higher layers doing another layer of locking to guard
against unplugged CPUs do the test here.

Signed-off-by: H. Peter Anvin <hpa@zytor.com>
This commit is contained in:
H. Peter Anvin 2008-08-25 17:07:14 -07:00
parent 2a61812af2
commit f73be6dedf
1 changed files with 7 additions and 3 deletions
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10
kernel/smp.c
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@ -210,8 +210,10 @@ int smp_call_function_single(int cpu, void (*func) (void *info), void *info,
{ {
struct call_single_data d; struct call_single_data d;
unsigned long flags; unsigned long flags;
/* prevent preemption and reschedule on another processor */ /* prevent preemption and reschedule on another processor,
as well as CPU removal */
int me = get_cpu(); int me = get_cpu();
int err = 0;
/* Can deadlock when called with interrupts disabled */ /* Can deadlock when called with interrupts disabled */
WARN_ON(irqs_disabled()); WARN_ON(irqs_disabled());
@ -220,7 +222,7 @@ int smp_call_function_single(int cpu, void (*func) (void *info), void *info,
local_irq_save(flags); local_irq_save(flags);
func(info); func(info);
local_irq_restore(flags); local_irq_restore(flags);
} else { } else if ((unsigned)cpu < NR_CPUS && cpu_online(cpu)) {
struct call_single_data *data = NULL; struct call_single_data *data = NULL;
if (!wait) { if (!wait) {
@ -236,10 +238,12 @@ int smp_call_function_single(int cpu, void (*func) (void *info), void *info,
data->func = func; data->func = func;
data->info = info; data->info = info;
generic_exec_single(cpu, data); generic_exec_single(cpu, data);
} else {
err = -ENXIO; /* CPU not online */
} }
put_cpu(); put_cpu();
return 0; return err;
} }
EXPORT_SYMBOL(smp_call_function_single); EXPORT_SYMBOL(smp_call_function_single);