Further to a January 2013 thread titled: "[PATCH] SG_SCSI_RESET ioctl
should only perform requested operation" by Jeremy Linton a patch (v3)
is presented that expands the existing ioctl to include "no_escalate"
versions to the existing resets. This requires no changes to SCSI low
level drivers (LLDs); it adds several more finely tuned reset options
to the user space. For example:

   /* This call remains the same, with the same escalating semantics
    * if the device (LU) reset fail. That is: on failure to try a
    * target reset and if that fails, try a bus reset, and if that fails
    * try a host (i.e. LLD) reset. */
   val = SG_SCSI_RESET_DEVICE;
   res = ioctl(<sg_or_block_fd>, SG_SCSI_RESET, &val);

   /* What follows is a new option introduced by this patch series. Only
    * a device reset is attempted. If that fails then an appropriate
    * error code is provided. N.B. There is no reset escalation. */
   val = SG_SCSI_RESET_DEVICE | SG_SCSI_RESET_NO_ESCALATE;
   res = ioctl(<sg_or_block_fd>, SG_SCSI_RESET, &val);

This patches applies to lk 3.17.0 and Christoph's drivers-for-3.18
tree. The sg_reset utility has been extended to use this new option
since sg3_utils-1.36 package which was released on 20130531.

v3 of this patch changes adding, subtracting and arithmetic
comparisons to the corresponding bitwise logical operations.
For example 'SG_SCSI_RESET_DEVICE + SG_SCSI_RESET_NO_ESCALATE' has
been changed to 'SG_SCSI_RESET_DEVICE | SG_SCSI_RESET_NO_ESCALATE'.

ChangeLog:
   - modify SG_SCSI_RESET ioctl so the SG_SCSI_RESET_NO_ESCALATE
     value may be OR-ed to the existing values. If so the existing
     device->target->bus->host escalation does not occur. The
     SG_SCSI_RESET ioctl is modified in both the sg driver and
     scsi_ioctl.c (so block devices can use it).
   - modify scsi_reset_provider() in the scsi_error.c file in a
     similar way to support this additional functionality.

Signed-off-by: Douglas Gilbert <dgilbert@interlog.com>