Add generic helpers for arch IPI function calls

This adds kernel/smp.c which contains helpers for IPI function calls. In
addition to supporting the existing smp_call_function() in a more efficient
manner, it also adds a more scalable variant called smp_call_function_single()
for calling a given function on a single CPU only.

The core of this is based on the x86-64 patch from Nick Piggin, lots of
changes since then. "Alan D. Brunelle" <Alan.Brunelle@hp.com> has
contributed lots of fixes and suggestions as well. Also thanks to
Paul E. McKenney <paulmck@linux.vnet.ibm.com> for reviewing RCU usage
and getting rid of the data allocation fallback deadlock.

Acked-by: Ingo Molnar <mingo@elte.hu>
Reviewed-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>

2 files changed, 9 insertions, 5 deletions

diff --git a/arch/Kconfig b/arch/Kconfig
index 3ea332b009e5..ad89a33d8c6e 100644
--- a/arch/Kconfig
+++ b/arch/Kconfig
@@ -39,3 +39,6 @@ config HAVE_KRETPROBES
 
 config HAVE_DMA_ATTRS
         def_bool n
+
+config USE_GENERIC_SMP_HELPERS
+        def_bool n
diff --git a/arch/sparc64/kernel/smp.c b/arch/sparc64/kernel/smp.c
index fa63c68a1819..b82d017a1744 100644
--- a/arch/sparc64/kernel/smp.c
+++ b/arch/sparc64/kernel/smp.c
@@ -816,8 +816,9 @@ extern unsigned long xcall_call_function;
  * You must not call this function with disabled interrupts or from a
  * hardware interrupt handler or from a bottom half handler.
  */
-static int smp_call_function_mask(void (*func)(void *info), void *info,
-                                  int nonatomic, int wait, cpumask_t mask)
+static int sparc64_smp_call_function_mask(void (*func)(void *info), void *info,
+                                          int nonatomic, int wait,
+                                          cpumask_t mask)
 {
         struct call_data_struct data;
         int cpus;
@@ -855,8 +856,8 @@ out_unlock:
 int smp_call_function(void (*func)(void *info), void *info,
                       int nonatomic, int wait)
 {
-        return smp_call_function_mask(func, info, nonatomic, wait,
-                                      cpu_online_map);
+        return sparc64_smp_call_function_mask(func, info, nonatomic, wait,
+                                                cpu_online_map);
 }
 
 void smp_call_function_client(int irq, struct pt_regs *regs)
@@ -893,7 +894,7 @@ static void tsb_sync(void *info)
 
 void smp_tsb_sync(struct mm_struct *mm)
 {
-        smp_call_function_mask(tsb_sync, mm, 0, 1, mm->cpu_vm_mask);
+        sparc64_smp_call_function_mask(tsb_sync, mm, 0, 1, mm->cpu_vm_mask);
 }
 
 extern unsigned long xcall_flush_tlb_mm;