[PATCH 1/2] membarrier: allow cpu_id to be set on more commands

[Dylan Yudaken <dyudaken@gmail.com>]

No reason to not allow MEMBARRIER_CMD_FLAG_CPU on
MEMBARRIER_CMD_PRIVATE_EXPEDITED or
MEMBARRIER_CMD_PRIVATE_EXPEDITED_SYNC_CORE.

If it is known specifically what cpu you want to interrupt then there
is a decent efficiency saving in not interrupting all the other ones.

Also - the code already works as is for them.

Signed-off-by: Dylan Yudaken <dyudaken@gmail.com>
---
 kernel/sched/membarrier.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/kernel/sched/membarrier.c b/kernel/sched/membarrier.c
index 809194cd779f..def6d4094ad6 100644
--- a/kernel/sched/membarrier.c
+++ b/kernel/sched/membarrier.c
@@ -595,7 +595,9 @@ static int membarrier_get_registrations(void)
  *          contains the CPU on which to interrupt (= restart)
  *          the RSEQ critical section.
  * @cpu_id: if @flags == MEMBARRIER_CMD_FLAG_CPU, indicates the cpu on which
- *          RSEQ CS should be interrupted (@cmd must be
+ *          RSEQ CS should be interrupted (@cmd must be one of
+ *          MEMBARRIER_CMD_PRIVATE_EXPEDITED,
+ *          MEMBARRIER_CMD_PRIVATE_EXPEDITED_SYNC_CORE,
  *          MEMBARRIER_CMD_PRIVATE_EXPEDITED_RSEQ).
  *
  * If this system call is not implemented, -ENOSYS is returned. If the
@@ -625,6 +627,8 @@ static int membarrier_get_registrations(void)
 SYSCALL_DEFINE3(membarrier, int, cmd, unsigned int, flags, int, cpu_id)
 {
 	switch (cmd) {
+	case MEMBARRIER_CMD_PRIVATE_EXPEDITED:
+	case MEMBARRIER_CMD_PRIVATE_EXPEDITED_SYNC_CORE:
 	case MEMBARRIER_CMD_PRIVATE_EXPEDITED_RSEQ:
 		if (unlikely(flags && flags != MEMBARRIER_CMD_FLAG_CPU))
 			return -EINVAL;
-- 
2.49.0