[PATCH v2 3/6] sg: reinstate cmd_len > 32

[Douglas Gilbert <dgilbert@interlog.com>]

Use the changes to include/scsi/scsi_cmnd.h in earlier patch
to use the scsi_cmnd_set_cdb() function to place a SCSI CDB
in the struct scsi_cmnd object.

When free-ing up a struct request, or its attached scsi_cmnd
sub-object, call scsi_free_cmnd() which ensures that if a
long cdb used its own heap allocation, then that heap is freed.

Signed-off-by: Douglas Gilbert <dgilbert@interlog.com>
---
 drivers/scsi/sg.c | 23 ++++++++++++-----------
 1 file changed, 12 insertions(+), 11 deletions(-)

diff --git a/drivers/scsi/sg.c b/drivers/scsi/sg.c
index cbffa712b9f3..653c172a6338 100644
--- a/drivers/scsi/sg.c
+++ b/drivers/scsi/sg.c
@@ -77,7 +77,7 @@ static int sg_proc_init(void);
  * of sg_io_hdr::cmd_len can only represent 255. All SCSI commands greater
  * than 16 bytes are "variable length" whose length is a multiple of 4
  */
-#define SG_MAX_CDB_SIZE 252
+#define SG_MAX_CDB_SIZE SCSI_MAX_RUN_TIME_8BIT_CDB_LEN
 
 #define SG_DEFAULT_TIMEOUT mult_frac(SG_DEFAULT_TIMEOUT_USER, HZ, USER_HZ)
 
@@ -813,7 +813,7 @@ sg_common_write(Sg_fd * sfp, Sg_request * srp,
 	}
 	if (atomic_read(&sdp->detaching)) {
 		if (srp->bio) {
-			blk_mq_free_request(srp->rq);
+			scsi_free_cmnd(blk_mq_rq_to_pdu(srp->rq));
 			srp->rq = NULL;
 		}
 
@@ -1387,7 +1387,7 @@ sg_rq_end_io(struct request *rq, blk_status_t status)
 	 * blk_rq_unmap_user() can be called from user context.
 	 */
 	srp->rq = NULL;
-	blk_mq_free_request(rq);
+	scsi_free_cmnd(scmd);
 
 	write_lock_irqsave(&sfp->rq_list_lock, iflags);
 	if (unlikely(srp->orphan)) {
@@ -1753,14 +1753,14 @@ sg_start_req(Sg_request *srp, unsigned char *cmd)
 		return PTR_ERR(rq);
 	scmd = blk_mq_rq_to_pdu(rq);
 
-	if (hp->cmd_len > sizeof(scmd->cmnd)) {
-		blk_mq_free_request(rq);
+	if (unlikely(hp->cmd_len > SCSI_MAX_RUN_TIME_CDB_LEN)) {
+		scsi_free_cmnd(scmd);
 		return -EINVAL;
 	}
-
-	memcpy(scmd->cmnd, cmd, hp->cmd_len);
-	scmd->cmd_len = hp->cmd_len;
-
+	if (unlikely(!scsi_cmnd_set_cdb(scmd, cmd, hp->cmd_len))) {
+		scsi_free_cmnd(scmd);
+		return -ENOMEM;
+	}
 	srp->rq = rq;
 	rq->end_io_data = srp;
 	scmd->allowed = SG_DEFAULT_RETRIES;
@@ -1845,6 +1845,7 @@ sg_finish_rem_req(Sg_request *srp)
 
 	Sg_fd *sfp = srp->parentfp;
 	Sg_scatter_hold *req_schp = &srp->data;
+	struct request *rq = srp->rq;
 
 	SCSI_LOG_TIMEOUT(4, sg_printk(KERN_INFO, sfp->parentdp,
 				      "sg_finish_rem_req: res_used=%d\n",
@@ -1852,8 +1853,8 @@ sg_finish_rem_req(Sg_request *srp)
 	if (srp->bio)
 		ret = blk_rq_unmap_user(srp->bio);
 
-	if (srp->rq)
-		blk_mq_free_request(srp->rq);
+	if (rq)
+		scsi_free_cmnd(blk_mq_rq_to_pdu(rq));
 
 	if (srp->res_used)
 		sg_unlink_reserve(sfp, srp);
-- 
2.25.1