mm/hmm: clean up some coding style and comments

There are no functional changes, just some coding style clean ups and
minor comment changes.

Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Ira Weiny <ira.weiny@intel.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Balbir Singh <bsingharora@gmail.com>
Cc: Dan Carpenter <dan.carpenter@oracle.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Souptick Joarder <jrdr.linux@gmail.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Ralph Campbell <rcampbell@nvidia.com>
Reviewed-by: Jérôme Glisse <jglisse@redhat.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>

mm/hmm.c

@@ -153,9 +153,8 @@ static void hmm_release(struct mmu_notifier *mn, struct mm_struct *mm)
 
 	/* Wake-up everyone waiting on any range. */
 	mutex_lock(&hmm->lock);
-	list_for_each_entry(range, &hmm->ranges, list) {
+	list_for_each_entry(range, &hmm->ranges, list)
 		range->valid = false;
-	}
 	wake_up_all(&hmm->wq);
 	mutex_unlock(&hmm->lock);
 
@@ -166,9 +165,10 @@ static void hmm_release(struct mmu_notifier *mn, struct mm_struct *mm)
 		list_del_init(&mirror->list);
 		if (mirror->ops->release) {
 			/*
-			 * Drop mirrors_sem so callback can wait on any pending
-			 * work that might itself trigger mmu_notifier callback
-			 * and thus would deadlock with us.
+			 * Drop mirrors_sem so the release callback can wait
+			 * on any pending work that might itself trigger a
+			 * mmu_notifier callback and thus would deadlock with
+			 * us.
 			 */
 			up_write(&hmm->mirrors_sem);
 			mirror->ops->release(mirror);
@@ -223,11 +223,8 @@ static int hmm_invalidate_range_start(struct mmu_notifier *mn,
 		int ret;
 
 		ret = mirror->ops->sync_cpu_device_pagetables(mirror, &update);
-		if (!update.blockable && ret == -EAGAIN) {
-			up_read(&hmm->mirrors_sem);
-			ret = -EAGAIN;
-			goto out;
-		}
+		if (!update.blockable && ret == -EAGAIN)
+			break;
 	}
 	up_read(&hmm->mirrors_sem);
 
@@ -271,6 +268,7 @@ static const struct mmu_notifier_ops hmm_mmu_notifier_ops = {
  *
  * @mirror: new mirror struct to register
  * @mm: mm to register against
+ * Return: 0 on success, -ENOMEM if no memory, -EINVAL if invalid arguments
  *
  * To start mirroring a process address space, the device driver must register
  * an HMM mirror struct.
@@ -298,7 +296,7 @@ EXPORT_SYMBOL(hmm_mirror_register);
 /*
  * hmm_mirror_unregister() - unregister a mirror
  *
- * @mirror: new mirror struct to register
+ * @mirror: mirror struct to unregister
  *
  * Stop mirroring a process address space, and cleanup.
  */
@@ -372,7 +370,7 @@ static int hmm_pfns_bad(unsigned long addr,
  * @fault: should we fault or not ?
  * @write_fault: write fault ?
  * @walk: mm_walk structure
- * Returns: 0 on success, -EBUSY after page fault, or page fault error
+ * Return: 0 on success, -EBUSY after page fault, or page fault error
  *
  * This function will be called whenever pmd_none() or pte_none() returns true,
  * or whenever there is no page directory covering the virtual address range.
@@ -911,6 +909,7 @@ int hmm_range_register(struct hmm_range *range,
 		       unsigned page_shift)
 {
 	unsigned long mask = ((1UL << page_shift) - 1UL);
+	struct hmm *hmm;
 
 	range->valid = false;
 	range->hmm = NULL;
@@ -924,28 +923,29 @@ int hmm_range_register(struct hmm_range *range,
 	range->start = start;
 	range->end = end;
 
-	range->hmm = hmm_get_or_create(mm);
-	if (!range->hmm)
+	hmm = hmm_get_or_create(mm);
+	if (!hmm)
 		return -EFAULT;
 
 	/* Check if hmm_mm_destroy() was call. */
-	if (range->hmm->mm == NULL || range->hmm->dead) {
-		hmm_put(range->hmm);
+	if (hmm->mm == NULL || hmm->dead) {
+		hmm_put(hmm);
 		return -EFAULT;
 	}
 
-	/* Initialize range to track CPU page table update */
-	mutex_lock(&range->hmm->lock);
+	/* Initialize range to track CPU page table updates. */
+	mutex_lock(&hmm->lock);
 
-	list_add_rcu(&range->list, &range->hmm->ranges);
+	range->hmm = hmm;
+	list_add_rcu(&range->list, &hmm->ranges);
 
 	/*
 	 * If there are any concurrent notifiers we have to wait for them for
 	 * the range to be valid (see hmm_range_wait_until_valid()).
 	 */
-	if (!range->hmm->notifiers)
+	if (!hmm->notifiers)
 		range->valid = true;
-	mutex_unlock(&range->hmm->lock);
+	mutex_unlock(&hmm->lock);
 
 	return 0;
 }
@@ -960,17 +960,19 @@ EXPORT_SYMBOL(hmm_range_register);
  */
 void hmm_range_unregister(struct hmm_range *range)
 {
+	struct hmm *hmm = range->hmm;
+
 	/* Sanity check this really should not happen. */
-	if (range->hmm == NULL || range->end <= range->start)
+	if (hmm == NULL || range->end <= range->start)
 		return;
 
-	mutex_lock(&range->hmm->lock);
+	mutex_lock(&hmm->lock);
 	list_del_rcu(&range->list);
-	mutex_unlock(&range->hmm->lock);
+	mutex_unlock(&hmm->lock);
 
 	/* Drop reference taken by hmm_range_register() */
 	range->valid = false;
-	hmm_put(range->hmm);
+	hmm_put(hmm);
 	range->hmm = NULL;
 }
 EXPORT_SYMBOL(hmm_range_unregister);
@@ -978,7 +980,7 @@ EXPORT_SYMBOL(hmm_range_unregister);
 /*
  * hmm_range_snapshot() - snapshot CPU page table for a range
  * @range: range
- * Returns: -EINVAL if invalid argument, -ENOMEM out of memory, -EPERM invalid
+ * Return: -EINVAL if invalid argument, -ENOMEM out of memory, -EPERM invalid
  *          permission (for instance asking for write and range is read only),
  *          -EAGAIN if you need to retry, -EFAULT invalid (ie either no valid
  *          vma or it is illegal to access that range), number of valid pages
@@ -1061,7 +1063,7 @@ EXPORT_SYMBOL(hmm_range_snapshot);
  * hmm_range_fault() - try to fault some address in a virtual address range
  * @range: range being faulted
  * @block: allow blocking on fault (if true it sleeps and do not drop mmap_sem)
- * Returns: number of valid pages in range->pfns[] (from range start
+ * Return: number of valid pages in range->pfns[] (from range start
  *          address). This may be zero. If the return value is negative,
  *          then one of the following values may be returned:
  *
@@ -1179,7 +1181,7 @@ EXPORT_SYMBOL(hmm_range_fault);
  * @device: device against to dma map page to
  * @daddrs: dma address of mapped pages
  * @block: allow blocking on fault (if true it sleeps and do not drop mmap_sem)
- * Returns: number of pages mapped on success, -EAGAIN if mmap_sem have been
+ * Return: number of pages mapped on success, -EAGAIN if mmap_sem have been
  *          drop and you need to try again, some other error value otherwise
  *
  * Note same usage pattern as hmm_range_fault().
@@ -1267,7 +1269,7 @@ EXPORT_SYMBOL(hmm_range_dma_map);
  * @device: device against which dma map was done
  * @daddrs: dma address of mapped pages
  * @dirty: dirty page if it had the write flag set
- * Returns: number of page unmapped on success, -EINVAL otherwise
+ * Return: number of page unmapped on success, -EINVAL otherwise
  *
  * Note that caller MUST abide by mmu notifier or use HMM mirror and abide
  * to the sync_cpu_device_pagetables() callback so that it is safe here to
@@ -1390,7 +1392,7 @@ static void hmm_devmem_free(struct page *page, void *data)
  * @ops: memory event device driver callback (see struct hmm_devmem_ops)
  * @device: device struct to bind the resource too
  * @size: size in bytes of the device memory to add
- * Returns: pointer to new hmm_devmem struct ERR_PTR otherwise
+ * Return: pointer to new hmm_devmem struct ERR_PTR otherwise
  *
  * This function first finds an empty range of physical address big enough to
  * contain the new resource, and then hotplugs it as ZONE_DEVICE memory, which