[PATCH v4 1/3] scsi: ufs-bsg: Change the calling convention for write descriptor

[Avri Altman]

When we had a write descriptor query upiu, we appended the descriptor
right after the bsg request.  This was fine as the bsg driver allows to
allocate whatever buffer we needed in its job request.

Still, the proper way to deliver payload, however small (we only write
config descriptors of 144 bytes), is by using the job request payload
data buffer.

So change this ABI now, while ufs-bsg is still new, and nobody is
actually using it.

Signed-off-by: Avri Altman <avri.altman@xxxxxxx>
Reviewed-by: Evan Green <evgreen@xxxxxxxxxxxx>
---
 Documentation/scsi/ufs.txt |  6 ++++++
 drivers/scsi/ufs/ufs_bsg.c | 47 +++++++++++++++++++++++++---------------------
 2 files changed, 32 insertions(+), 21 deletions(-)

diff --git a/Documentation/scsi/ufs.txt b/Documentation/scsi/ufs.txt
index 520b5b0..78fe7cb 100644
--- a/Documentation/scsi/ufs.txt
+++ b/Documentation/scsi/ufs.txt
@@ -147,6 +147,12 @@ send SG_IO with the applicable sg_io_v4:
 	io_hdr_v4.max_response_len = reply_len;
 	io_hdr_v4.request_len = request_len;
 	io_hdr_v4.request = (__u64)request_upiu;
+	if (dir == SG_DXFER_TO_DEV) {
+		io_hdr_v4.dout_xfer_len = (uint32_t)byte_cnt;
+		io_hdr_v4.dout_xferp = (uintptr_t)(__u64)buff;
+	}
+
+If you wish to write a descriptor, use the dout_xferp sg_io_v4.
 
 UFS Specifications can be found at,
 UFS - http://www.jedec.org/sites/default/files/docs/JESD220.pdf
diff --git a/drivers/scsi/ufs/ufs_bsg.c b/drivers/scsi/ufs/ufs_bsg.c
index 775bb4e..2fd0769 100644
--- a/drivers/scsi/ufs/ufs_bsg.c
+++ b/drivers/scsi/ufs/ufs_bsg.c
@@ -27,15 +27,11 @@ static int ufs_bsg_get_query_desc_size(struct ufs_hba *hba, int *desc_len,
 
 static int ufs_bsg_verify_query_size(struct ufs_hba *hba,
 				     unsigned int request_len,
-				     unsigned int reply_len,
-				     int desc_len, enum query_opcode desc_op)
+				     unsigned int reply_len)
 {
 	int min_req_len = sizeof(struct ufs_bsg_request);
 	int min_rsp_len = sizeof(struct ufs_bsg_reply);
 
-	if (desc_op == UPIU_QUERY_OPCODE_WRITE_DESC)
-		min_req_len += desc_len;
-
 	if (min_req_len > request_len || min_rsp_len > reply_len) {
 		dev_err(hba->dev, "not enough space assigned\n");
 		return -EINVAL;
@@ -44,14 +40,13 @@ static int ufs_bsg_verify_query_size(struct ufs_hba *hba,
 	return 0;
 }
 
-static int ufs_bsg_verify_query_params(struct ufs_hba *hba,
-				       struct ufs_bsg_request *bsg_request,
-				       unsigned int request_len,
-				       unsigned int reply_len,
-				       uint8_t *desc_buff, int *desc_len,
-				       enum query_opcode desc_op)
+static int ufs_bsg_alloc_desc_buffer(struct ufs_hba *hba, struct bsg_job *job,
+				     uint8_t **desc_buff, int *desc_len,
+				     enum query_opcode desc_op)
 {
+	struct ufs_bsg_request *bsg_request = job->request;
 	struct utp_upiu_query *qr;
+	u8 *descp;
 
 	if (desc_op == UPIU_QUERY_OPCODE_READ_DESC) {
 		dev_err(hba->dev, "unsupported opcode %d\n", desc_op);
@@ -67,11 +62,19 @@ static int ufs_bsg_verify_query_params(struct ufs_hba *hba,
 		return -EINVAL;
 	}
 
-	if (ufs_bsg_verify_query_size(hba, request_len, reply_len, *desc_len,
-				      desc_op))
+	if (*desc_len > job->request_payload.payload_len) {
+		dev_err(hba->dev, "Illegal desc size\n");
 		return -EINVAL;
+	}
+
+	descp = kzalloc(*desc_len, GFP_KERNEL);
+	if (!descp)
+		return -ENOMEM;
 
-	desc_buff = (uint8_t *)(bsg_request + 1);
+	sg_copy_to_buffer(job->request_payload.sg_list,
+			  job->request_payload.sg_cnt, descp, *desc_len);
+
+	*desc_buff = descp;
 
 out:
 	return 0;
@@ -91,7 +94,7 @@ static int ufs_bsg_request(struct bsg_job *job)
 	enum query_opcode desc_op = UPIU_QUERY_OPCODE_NOP;
 	int ret;
 
-	ret = ufs_bsg_verify_query_size(hba, req_len, reply_len, 0, desc_op);
+	ret = ufs_bsg_verify_query_size(hba, req_len, reply_len);
 	if (ret)
 		goto out;
 
@@ -101,9 +104,8 @@ static int ufs_bsg_request(struct bsg_job *job)
 	switch (msgcode) {
 	case UPIU_TRANSACTION_QUERY_REQ:
 		desc_op = bsg_request->upiu_req.qr.opcode;
-		ret = ufs_bsg_verify_query_params(hba, bsg_request, req_len,
-						  reply_len, desc_buff,
-						  &desc_len, desc_op);
+		ret = ufs_bsg_alloc_desc_buffer(hba, job, &desc_buff,
+						&desc_len, desc_op);
 		if (ret)
 			goto out;
 
@@ -135,11 +137,14 @@ static int ufs_bsg_request(struct bsg_job *job)
 		break;
 	}
 
+	if (!desc_buff)
+		goto out;
+
+	kfree(desc_buff);
+
 out:
 	bsg_reply->result = ret;
-	job->reply_len = sizeof(struct ufs_bsg_reply) +
-			 bsg_reply->reply_payload_rcv_len;
-
+	job->reply_len = sizeof(struct ufs_bsg_reply);
 	bsg_job_done(job, ret, bsg_reply->reply_payload_rcv_len);
 
 	return ret;
-- 
1.9.1