Commit bd428b8c authored by David Hildenbrand's avatar David Hildenbrand Committed by Claudio Imbrenda
Browse files

s390/uv: Always return 0 from s390_wiggle_split_folio() if successful 



Let's consistently return 0 if the operation was successful, and just
detect ourselves whether splitting is required -- folio_test_large() is
a cheap operation.

Update the documentation.

Should we simply always return -EAGAIN instead of 0, so we don't have
to handle it in the caller? Not sure, staring at the documentation, this
way looks a bit cleaner.

Signed-off-by: default avatarDavid Hildenbrand <david@redhat.com>
Link: https://lore.kernel.org/r/20250516123946.1648026-3-david@redhat.com


Message-ID: <20250516123946.1648026-3-david@redhat.com>
Reviewed-by: default avatarClaudio Imbrenda <imbrenda@linux.ibm.com>
Signed-off-by: default avatarClaudio Imbrenda <imbrenda@linux.ibm.com>
parent 3ec8a833

arch/s390/kernel/uv.c

+12 −10
Original line number Diff line number Diff line
@@ -324,35 +324,37 @@ static int make_folio_secure(struct mm_struct *mm, struct folio *folio, struct u 
}



/**

 * s390_wiggle_split_folio() - try to drain extra references to a folio and optionally split.

 * s390_wiggle_split_folio() - try to drain extra references to a folio and

 *			       split the folio if it is large.

 * @mm:    the mm containing the folio to work on

 * @folio: the folio

 * @split: whether to split a large folio

 *

 * Context: Must be called while holding an extra reference to the folio;

 *          the mm lock should not be held.

 * Return: 0 if the folio was split successfully;

 *         -EAGAIN if the folio was not split successfully but another attempt

 *                 can be made, or if @split was set to false;

 *         -EINVAL in case of other errors. See split_folio().

 * Return: 0 if the operation was successful;

 *	   -EAGAIN if splitting the large folio was not successful,

 *		   but another attempt can be made;

 *	   -EINVAL in case of other folio splitting errors. See split_folio().

 */

static int s390_wiggle_split_folio(struct mm_struct *mm, struct folio *folio, bool split)

static int s390_wiggle_split_folio(struct mm_struct *mm, struct folio *folio)

{

	int rc;



	lockdep_assert_not_held(&mm->mmap_lock);

	folio_wait_writeback(folio);

	lru_add_drain_all();

	if (split) {



	if (folio_test_large(folio)) {

		folio_lock(folio);

		rc = split_folio(folio);

		folio_unlock(folio);



		if (rc != -EBUSY)

			return rc;

	}

		return -EAGAIN;

	}

	return 0;

}



int make_hva_secure(struct mm_struct *mm, unsigned long hva, struct uv_cb_header *uvcb)

{
@@ -394,7 +396,7 @@ int make_hva_secure(struct mm_struct *mm, unsigned long hva, struct uv_cb_header 
	mmap_read_unlock(mm);



	if (rc == -E2BIG || rc == -EBUSY) {

		rc = s390_wiggle_split_folio(mm, folio, rc == -E2BIG);

		rc = s390_wiggle_split_folio(mm, folio);

		if (!rc)

			rc = -EAGAIN;

	}