[PATCH 4/8] snd: make snd_map_bufs() deal with ITER_UBUF

[Jens Axboe <axboe@kernel.dk>]

This probably doesn't make any sense, as it's reliant on passing in
different things in multiple segments. Most likely we can just make
this go away as it's already checking for ITER_IOVEC upon entry, and
it looks like nr_segments == 2 is the smallest legal value. IOW, any
attempt to readv/writev with 1 segment would fail with -EINVAL already.

Signed-off-by: Jens Axboe <axboe@kernel.dk>
---
 sound/core/pcm_native.c | 17 +++++++++++------
 1 file changed, 11 insertions(+), 6 deletions(-)

diff --git a/sound/core/pcm_native.c b/sound/core/pcm_native.c
index 925d96343148..05913d68923a 100644
--- a/sound/core/pcm_native.c
+++ b/sound/core/pcm_native.c
@@ -3516,23 +3516,28 @@ static void __user **snd_map_bufs(struct snd_pcm_runtime *runtime,
 				  struct iov_iter *iter,
 				  snd_pcm_uframes_t *frames, int max_segs)
 {
+	int nr_segs = iovec_nr_user_vecs(iter);
 	void __user **bufs;
+	struct iovec iov;
 	unsigned long i;
 
 	if (!iter->user_backed)
 		return ERR_PTR(-EFAULT);
-	if (!iter->nr_segs)
+	if (!nr_segs)
 		return ERR_PTR(-EINVAL);
-	if (iter->nr_segs > max_segs || iter->nr_segs != runtime->channels)
+	if (nr_segs > max_segs || nr_segs != runtime->channels)
 		return ERR_PTR(-EINVAL);
-	if (!frame_aligned(runtime, iter->iov->iov_len))
+	iov = iov_iter_iovec(iter);
+	if (!frame_aligned(runtime, iov.iov_len))
 		return ERR_PTR(-EINVAL);
-	bufs = kmalloc_array(iter->nr_segs, sizeof(void *), GFP_KERNEL);
+	bufs = kmalloc_array(nr_segs, sizeof(void *), GFP_KERNEL);
 	if (bufs == NULL)
 		return ERR_PTR(-ENOMEM);
-	for (i = 0; i < iter->nr_segs; ++i)
+	bufs[0] = iov.iov_base;
+	/* we know it's an ITER_IOVEC is nr_segs > 1 */
+	for (i = 1; i < nr_segs; ++i)
 		bufs[i] = iter->iov[i].iov_base;
-	*frames = bytes_to_samples(runtime, iter->iov->iov_len);
+	*frames = bytes_to_samples(runtime, iov.iov_len);
 	return bufs;
 }
 
-- 
2.39.2