smp: Consolidate the various smp_call_function_single() declensions

__smp_call_function_single() and smp_call_function_single() share some
code that can be factorized: execute inline when the target is local,
check if the target is online, lock the csd, call generic_exec_single().

Lets move the common parts to generic_exec_single().

Reviewed-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: Jan Kara <jack@suse.cz>
Cc: Jens Axboe <axboe@fb.com>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: Jens Axboe <axboe@fb.com>

1 files changed, 39 insertions, 41 deletions

diff --git a/kernel/smp.c b/kernel/smp.c
index 5ff14e3739ca..64bb0d48e96f 100644
--- a/kernel/smp.c
+++ b/kernel/smp.c
@@ -117,13 +117,43 @@ static void csd_unlock(struct call_single_data *csd)
         csd->flags &= ~CSD_FLAG_LOCK;
 }
 
+static DEFINE_PER_CPU_SHARED_ALIGNED(struct call_single_data, csd_data);
+
 /*
  * Insert a previously allocated call_single_data element
  * for execution on the given CPU. data must already have
  * ->func, ->info, and ->flags set.
  */
-static void generic_exec_single(int cpu, struct call_single_data *csd, int wait)
+static int generic_exec_single(int cpu, struct call_single_data *csd,
+                               smp_call_func_t func, void *info, int wait)
 {
+        struct call_single_data csd_stack = { .flags = 0 };
+        unsigned long flags;
+
+
+        if (cpu == smp_processor_id()) {
+                local_irq_save(flags);
+                func(info);
+                local_irq_restore(flags);
+                return 0;
+        }
+
+
+        if ((unsigned)cpu >= nr_cpu_ids || !cpu_online(cpu))
+                return -ENXIO;
+
+
+        if (!csd) {
+                csd = &csd_stack;
+                if (!wait)
+                        csd = &__get_cpu_var(csd_data);
+        }
+
+        csd_lock(csd);
+
+        csd->func = func;
+        csd->info = info;
+
         if (wait)
                 csd->flags |= CSD_FLAG_WAIT;
 
@@ -143,6 +173,8 @@ static void generic_exec_single(int cpu, struct call_single_data *csd, int wait)
 
         if (wait)
                 csd_lock_wait(csd);
+
+        return 0;
 }
 
 /*
@@ -168,8 +200,6 @@ void generic_smp_call_function_single_interrupt(void)
         }
 }
 
-static DEFINE_PER_CPU_SHARED_ALIGNED(struct call_single_data, csd_data);
-
 /*
  * smp_call_function_single - Run a function on a specific CPU
  * @func: The function to run. This must be fast and non-blocking.
@@ -181,12 +211,8 @@ static DEFINE_PER_CPU_SHARED_ALIGNED(struct call_single_data, csd_data);
 int smp_call_function_single(int cpu, smp_call_func_t func, void *info,
                              int wait)
 {
-        struct call_single_data d = {
-                .flags = 0,
-        };
-        unsigned long flags;
         int this_cpu;
-        int err = 0;
+        int err;
 
         /*
          * prevent preemption and reschedule on another processor,
@@ -203,26 +229,7 @@ int smp_call_function_single(int cpu, smp_call_func_t func, void *info,
         WARN_ON_ONCE(cpu_online(this_cpu) && irqs_disabled()
                      && !oops_in_progress);
 
-        if (cpu == this_cpu) {
-                local_irq_save(flags);
-                func(info);
-                local_irq_restore(flags);
-        } else {
-                if ((unsigned)cpu < nr_cpu_ids && cpu_online(cpu)) {
-                        struct call_single_data *csd = &d;
-
-                        if (!wait)
-                                csd = &__get_cpu_var(csd_data);
-
-                        csd_lock(csd);
-
-                        csd->func = func;
-                        csd->info = info;
-                        generic_exec_single(cpu, csd, wait);
-                } else {
-                        err = -ENXIO;   /* CPU not online */
-                }
-        }
+        err = generic_exec_single(cpu, NULL, func, info, wait);
 
         put_cpu();
 
@@ -285,9 +292,8 @@ EXPORT_SYMBOL_GPL(smp_call_function_any);
  */
 int __smp_call_function_single(int cpu, struct call_single_data *csd, int wait)
 {
-        unsigned int this_cpu;
-        unsigned long flags;
         int err = 0;
+        int this_cpu;
 
         this_cpu = get_cpu();
         /*
@@ -296,20 +302,12 @@ int __smp_call_function_single(int cpu, struct call_single_data *csd, int wait)
          * send smp call function interrupt to this cpu and as such deadlocks
          * can't happen.
          */
-        WARN_ON_ONCE(cpu_online(smp_processor_id()) && wait && irqs_disabled()
+        WARN_ON_ONCE(cpu_online(this_cpu) && wait && irqs_disabled()
                      && !oops_in_progress);
 
-        if (cpu == this_cpu) {
-                local_irq_save(flags);
-                csd->func(csd->info);
-                local_irq_restore(flags);
-        } 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 */
-        }
+        err = generic_exec_single(cpu, csd, csd->func, csd->info, wait);
         put_cpu();
+
         return err;
 }
 EXPORT_SYMBOL_GPL(__smp_call_function_single);