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Subject[PATCH 06/11] smp: Teach __smp_call_function_single() to check for offline cpus
Date
From: Jan Kara <jack@suse.cz>

Align __smp_call_function_single() with smp_call_function_single() so
that it also checks whether requested cpu is still online.

Signed-off-by: Jan Kara <jack@suse.cz>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Jens Axboe <jens.axboe@oracle.com>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
---
include/linux/smp.h | 3 +--
kernel/smp.c | 11 +++++++----
kernel/up.c | 5 +++--
3 files changed, 11 insertions(+), 8 deletions(-)

diff --git a/include/linux/smp.h b/include/linux/smp.h
index 9a1b8ba..1e8c721 100644
--- a/include/linux/smp.h
+++ b/include/linux/smp.h
@@ -50,8 +50,7 @@ void on_each_cpu_cond(bool (*cond_func)(int cpu, void *info),
smp_call_func_t func, void *info, bool wait,
gfp_t gfp_flags);

-void __smp_call_function_single(int cpuid, struct call_single_data *data,
- int wait);
+int __smp_call_function_single(int cpu, struct call_single_data *csd, int wait);

#ifdef CONFIG_SMP

diff --git a/kernel/smp.c b/kernel/smp.c
index e3852de..5ff14e3 100644
--- a/kernel/smp.c
+++ b/kernel/smp.c
@@ -276,18 +276,18 @@ EXPORT_SYMBOL_GPL(smp_call_function_any);
/**
* __smp_call_function_single(): Run a function on a specific CPU
* @cpu: The CPU to run on.
- * @data: Pre-allocated and setup data structure
+ * @csd: Pre-allocated and setup data structure
* @wait: If true, wait until function has completed on specified CPU.
*
* Like smp_call_function_single(), but allow caller to pass in a
* pre-allocated data structure. Useful for embedding @data inside
* other structures, for instance.
*/
-void __smp_call_function_single(int cpu, struct call_single_data *csd,
- int wait)
+int __smp_call_function_single(int cpu, struct call_single_data *csd, int wait)
{
unsigned int this_cpu;
unsigned long flags;
+ int err = 0;

this_cpu = get_cpu();
/*
@@ -303,11 +303,14 @@ void __smp_call_function_single(int cpu, struct call_single_data *csd,
local_irq_save(flags);
csd->func(csd->info);
local_irq_restore(flags);
- } else {
+ } else if ((unsigned)cpu < nr_cpu_ids && cpu_online(cpu)) {
csd_lock(csd);
generic_exec_single(cpu, csd, wait);
+ } else {
+ err = -ENXIO; /* CPU not online */
}
put_cpu();
+ return err;
}
EXPORT_SYMBOL_GPL(__smp_call_function_single);

diff --git a/kernel/up.c b/kernel/up.c
index 509403e..cdf03d1 100644
--- a/kernel/up.c
+++ b/kernel/up.c
@@ -22,14 +22,15 @@ int smp_call_function_single(int cpu, void (*func) (void *info), void *info,
}
EXPORT_SYMBOL(smp_call_function_single);

-void __smp_call_function_single(int cpu, struct call_single_data *csd,
- int wait)
+int __smp_call_function_single(int cpu, struct call_single_data *csd,
+ int wait)
{
unsigned long flags;

local_irq_save(flags);
csd->func(csd->info);
local_irq_restore(flags);
+ return 0;
}
EXPORT_SYMBOL(__smp_call_function_single);

--
1.8.3.1


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