Re: [PATCH v3] SG_SCSI_RESET ioctl: add no_escalate values

[Hannes Reinecke <hare@suse.de>]

On 10/18/2014 10:11 PM, Douglas Gilbert wrote:
> 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>

Reviewed-by: Hannes Reinecke <hare@suse.de>

Cheers,

Hannes
-- 
Dr. Hannes Reinecke		      zSeries & Storage
hare@suse.de			      +49 911 74053 688
SUSE LINUX Products GmbH, Maxfeldstr. 5, 90409 Nürnberg
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