[RFC,v2,3/3] smp: Change signatures to use call_single_data_t

Commit Message

Leonardo Bras May 20, 2023, 5:29 a.m. UTC

Every caller of smp_call_function_single_async() now makes use
of call_single_data_t, which is a size-aligned typedef of
struct __call_single_data.

Changing smp_call_function_single_async() csd parameter to
call_single_data_t makes possible to warn future callers if they
are using an unaligned csd, which can cause it to be split between 2
cachelines, which is usually bad for performance.

Also, for the same reason, change generic_exec_single().

Signed-off-by: Leonardo Bras <[e-mail]>
---
 include/linux/smp.h | 2 +-
 kernel/smp.c        | 4 ++--
 kernel/up.c         | 2 +-
 3 files changed, 4 insertions(+), 4 deletions(-)

Patch

diff --git a/include/linux/smp.h b/include/linux/smp.h
index 91ea4a67f8ca..e87520dc2959 100644
--- a/include/linux/smp.h
+++ b/include/linux/smp.h
@@ -53,7 +53,7 @@  int smp_call_function_single(int cpuid, smp_call_func_t func, void *info,
 void on_each_cpu_cond_mask(smp_cond_func_t cond_func, smp_call_func_t func,
 			   void *info, bool wait, const struct cpumask *mask);
 
-int smp_call_function_single_async(int cpu, struct __call_single_data *csd);
+int smp_call_function_single_async(int cpu, call_single_data_t *csd);
 
 /*
  * Cpus stopping functions in panic. All have default weak definitions.
diff --git a/kernel/smp.c b/kernel/smp.c
index ab3e5dad6cfe..919387be6d4e 100644
--- a/kernel/smp.c
+++ b/kernel/smp.c
@@ -361,7 +361,7 @@  void __smp_call_single_queue(int cpu, struct llist_node *node)
  * for execution on the given CPU. data must already have
  * ->func, ->info, and ->flags set.
  */
-static int generic_exec_single(int cpu, struct __call_single_data *csd)
+static int generic_exec_single(int cpu, call_single_data_t *csd)
 {
 	if (cpu == smp_processor_id()) {
 		smp_call_func_t func = csd->func;
@@ -645,7 +645,7 @@  EXPORT_SYMBOL(smp_call_function_single);
  *
  * Return: %0 on success or negative errno value on error
  */
-int smp_call_function_single_async(int cpu, struct __call_single_data *csd)
+int smp_call_function_single_async(int cpu, call_single_data_t *csd)
 {
 	int err = 0;
 
diff --git a/kernel/up.c b/kernel/up.c
index a38b8b095251..df50828cc2f0 100644
--- a/kernel/up.c
+++ b/kernel/up.c
@@ -25,7 +25,7 @@  int smp_call_function_single(int cpu, void (*func) (void *info), void *info,
 }
 EXPORT_SYMBOL(smp_call_function_single);
 
-int smp_call_function_single_async(int cpu, struct __call_single_data *csd)
+int smp_call_function_single_async(int cpu, call_single_data_t *csd)
 {
 	unsigned long flags;