[RFC PATCH 07/11] mm/hmm: Delete hmm_mirror_mm_is_alive()

[Jason Gunthorpe <jgg@xxxxxxxx>]

From: Jason Gunthorpe <jgg@xxxxxxxxxxxx>

Now that it is clarified that callers to hmm_range_dma_map() must hold
the mmap_sem and thus the mmget, there is no purpose for this function.

It was the last user of dead, so delete it as well.

Signed-off-by: Jason Gunthorpe <jgg@xxxxxxxxxxxx>
---
 include/linux/hmm.h | 27 ---------------------------
 mm/hmm.c            |  4 ----
 2 files changed, 31 deletions(-)

diff --git a/include/linux/hmm.h b/include/linux/hmm.h
index 7f3b751fcab1ce..6671643703a7ab 100644
--- a/include/linux/hmm.h
+++ b/include/linux/hmm.h
@@ -91,7 +91,6 @@
  * @mirrors_sem: read/write semaphore protecting the mirrors list
  * @wq: wait queue for user waiting on a range invalidation
  * @notifiers: count of active mmu notifiers
- * @dead: is the mm dead ?
  */
 struct hmm {
 	struct mm_struct	*mm;
@@ -104,7 +103,6 @@ struct hmm {
 	wait_queue_head_t	wq;
 	struct rcu_head		rcu;
 	long			notifiers;
-	bool			dead;
 };
 
 /*
@@ -466,31 +464,6 @@ struct hmm_mirror {
 int hmm_mirror_register(struct hmm_mirror *mirror, struct mm_struct *mm);
 void hmm_mirror_unregister(struct hmm_mirror *mirror);
 
-/*
- * hmm_mirror_mm_is_alive() - test if mm is still alive
- * @mirror: the HMM mm mirror for which we want to lock the mmap_sem
- * Returns: false if the mm is dead, true otherwise
- *
- * This is an optimization it will not accurately always return -EINVAL if the
- * mm is dead ie there can be false negative (process is being kill but HMM is
- * not yet inform of that). It is only intented to be use to optimize out case
- * where driver is about to do something time consuming and it would be better
- * to skip it if the mm is dead.
- */
-static inline bool hmm_mirror_mm_is_alive(struct hmm_mirror *mirror)
-{
-	struct mm_struct *mm;
-
-	if (!mirror || !mirror->hmm)
-		return false;
-	mm = READ_ONCE(mirror->hmm->mm);
-	if (mirror->hmm->dead || !mm)
-		return false;
-
-	return true;
-}
-
-
 /*
  * Please see Documentation/vm/hmm.rst for how to use the range API.
  */
diff --git a/mm/hmm.c b/mm/hmm.c
index d97ec293336ea5..2695925c0c5927 100644
--- a/mm/hmm.c
+++ b/mm/hmm.c
@@ -80,7 +80,6 @@ static struct hmm *hmm_get_or_create(struct mm_struct *mm)
 	mutex_init(&hmm->lock);
 	kref_init(&hmm->kref);
 	hmm->notifiers = 0;
-	hmm->dead = false;
 	hmm->mm = mm;
 	mmgrab(hmm->mm);
 
@@ -130,9 +129,6 @@ static void hmm_release(struct mmu_notifier *mn, struct mm_struct *mm)
 	if (!kref_get_unless_zero(&hmm->kref))
 		return;
 
-	/* Report this HMM as dying. */
-	hmm->dead = true;
-
 	/* Wake-up everyone waiting on any range. */
 	mutex_lock(&hmm->lock);
 	list_for_each_entry(range, &hmm->ranges, list) {
-- 
2.21.0