[PATCH 0/6] scsi: fix scsi_cmd::cmd_len

From: Douglas Gilbert <dgilbert@interlog.com>
To: linux-scsi@vger.kernel.org
Cc: martin.petersen@oracle.com, jejb@linux.vnet.ibm.com,
	hare@suse.de, bvanassche@acm.org, hch@lst.de
Subject: [PATCH 0/6] scsi: fix scsi_cmd::cmd_len
Date: Thu,  7 Apr 2022 23:56:45 -0400	[thread overview]
Message-ID: <20220408035651.6472-1-dgilbert@interlog.com> (raw)

As described in the first patch of this set, commit ce70fd9a551af
reduced the maximum size of any SCSI commands (CDB length) to
32 bytes. It was previously larger in struct scsi_request which
has now (lk 5.18.0-rc1) been removed.

Use a slightly different scheme than before to support CDB lengths
greater than 32 bytes. Two access function are added, one for read
access, the other for create/write access to the CDB held inside
a scsi_cmnd object.

A scsi_cmnd object is always paired with a struct request object
that immediately precedes it. To note this pairing the new comments
refer to a scsi_cmnd "sub-object". Prior to this patch the
constructor/destructor naming was obscure:
   - scsi_alloc_request() to create a pair
   - blk_mq_free_request() to destruct a pair

Add a new destructor function:
   scsi_free_cmnd(struct scsi_cmnd *scmd)

to make this a bit clearer. Also scsi_free_cmnd() will free up a
pointer to a long cdb buffer on the heap, if one is present.

These changes have been applied to SCSI mid-level and the upper
level drivers (ULDs, e.g. sd). Only one low level driver (LLD)
has been updated: scsi_debug. The rest of the LLDs can continue
to use scsi_cmnd::cmnd directly _unless_ they wish to support
CDB lengths > 32 bytes; in that case they should use
scsi_cmnd_get_cdb().

This patchset is against lk 5.18.0-rc1 and also applies cleanly
to MKP's 5.19/scsi-queue branch.

Douglas Gilbert (6):
  scsi_cmnd: reinstate support for cmd_len > 32
  sd, sd_zbc: use scsi_cmnd cdb access functions
  sg: reinstate cmd_len > 32
  bsg: allow cmd_len > 32
  scsi_debug: reinstate cmd_len > 32
  st,sr: use scsi_cmnd cdb access functions and dtor

 drivers/scsi/scsi_bsg.c     |  22 +-
 drivers/scsi/scsi_debug.c   | 410 +++++++++++++++++++-----------------
 drivers/scsi/scsi_debugfs.c |   2 +-
 drivers/scsi/scsi_error.c   |  76 ++++---
 drivers/scsi/scsi_ioctl.c   |  21 +-
 drivers/scsi/scsi_lib.c     |  75 ++++++-
 drivers/scsi/scsi_logging.c |  11 +-
 drivers/scsi/sd.c           | 176 +++++++++-------
 drivers/scsi/sd_zbc.c       |  12 +-
 drivers/scsi/sg.c           |  21 +-
 drivers/scsi/sr.c           |  24 ++-
 drivers/scsi/st.c           |  12 +-
 include/scsi/scsi_cmnd.h    |  71 ++++++-
 include/scsi/scsi_eh.h      |   6 +-
 14 files changed, 565 insertions(+), 374 deletions(-)

-- 
2.25.1