sched: Add a PF flag for ksoftirqd identification

To account softirq time cleanly in scheduler, we need to identify whether
softirq is invoked in ksoftirqd context or softirq at hardirq tail context.
Add PF_KSOFTIRQD for that purpose.

As all PF flag bits are currently taken, create space by moving one of the
infrequently used bits (PF_THREAD_BOUND) down in task_struct to be along
with some other state fields.

Signed-off-by: Venkatesh Pallipadi <venki@google.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <1286237003-12406-4-git-send-email-venki@google.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

2 files changed, 2 insertions, 0 deletions

diff --git a/include/linux/sched.h b/include/linux/sched.h
index 8744e50cb083..aca0ce675939 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -1682,6 +1682,7 @@ extern void thread_group_times(struct task_struct *p, cputime_t *ut, cputime_t *
 /*
  * Per process flags
  */
+#define PF_KSOFTIRQD    0x00000001      /* I am ksoftirqd */
 #define PF_STARTING     0x00000002      /* being created */
 #define PF_EXITING      0x00000004      /* getting shut down */
 #define PF_EXITPIDONE   0x00000008      /* pi exit done on shut down */
diff --git a/kernel/softirq.c b/kernel/softirq.c
index 988dfbe6bbe8..267f7b763ebb 100644
--- a/kernel/softirq.c
+++ b/kernel/softirq.c
@@ -713,6 +713,7 @@ static int run_ksoftirqd(void * __bind_cpu)
 {
         set_current_state(TASK_INTERRUPTIBLE);
 
+        current->flags |= PF_KSOFTIRQD;
         while (!kthread_should_stop()) {
                 preempt_disable();
                 if (!local_softirq_pending()) {