Commit 89ab2d39 authored by Hans Verkuil's avatar Hans Verkuil Committed by Mauro Carvalho Chehab
Browse files

media: vb2: frame_vector.c: don't overwrite error code 



get_vaddr_frames() first calls pin_user_pages_fast() and if
that fails tries follow_pfn(). But if that also fails, then
the error code from pin_user_pages_fast() is overwritten with
the error code from follow_pfn().

Specifically if pin_user_pages_fast() returns -ENOMEM, then
follow_pfn() will overwrite that with -EINVAL, which is very
confusing.

So store the error code from pin_user_pages_fast() and return
that if follow_pfn() returns -EINVAL. -EINVAL indicates that
the page is unsuitable for follow_pfn, so pin_user_pages_fast()
was the correct call to make, and that error code should be
returned instead.

Signed-off-by: default avatarHans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: default avatarMauro Carvalho Chehab <mchehab+huawei@kernel.org>
parent fadecf79

drivers/media/common/videobuf2/frame_vector.c

+14 −1
Original line number Diff line number Diff line
@@ -37,6 +37,7 @@ int get_vaddr_frames(unsigned long start, unsigned int nr_frames, 
{

	struct mm_struct *mm = current->mm;

	struct vm_area_struct *vma;

	int ret_pin_user_pages_fast = 0;

	int ret = 0;

	int err;
@@ -56,6 +57,7 @@ int get_vaddr_frames(unsigned long start, unsigned int nr_frames, 
		vec->is_pfns = false;

		goto out_unlocked;

	}

	ret_pin_user_pages_fast = ret;



	mmap_read_lock(mm);

	vec->got_ref = false;
@@ -71,7 +73,18 @@ int get_vaddr_frames(unsigned long start, unsigned int nr_frames, 
		while (ret < nr_frames && start + PAGE_SIZE <= vma->vm_end) {

			err = follow_pfn(vma, start, &nums[ret]);

			if (err) {

				if (ret == 0)

				if (ret)

					goto out;

				// If follow_pfn() returns -EINVAL, then this

				// is not an IO mapping or a raw PFN mapping.

				// In that case, return the original error from

				// pin_user_pages_fast(). Otherwise this

				// function would return -EINVAL when

				// pin_user_pages_fast() returned -ENOMEM,

				// which makes debugging hard.

				if (err == -EINVAL && ret_pin_user_pages_fast)

					ret = ret_pin_user_pages_fast;

				else

					ret = err;

				goto out;

			}