Re: [PATCH v2] scsi: Fix scsi_get/set_resid() interface

Bart Van Assche <bvanassche@xxxxxxx> · Wed, 30 Oct 2019 08:15:15 -0700

On 10/30/19 2:08 AM, Damien Le Moal wrote:
struct scsi_cmnd cmd->req.resid_len which is returned and set
respectively by the helper functions scsi_get_resid() and
scsi_set_resid() is an unsigned int. Reflect this fact in the interface
of these helper functions.

Also fix compilation errors due to min() and max() type mismatch
introduced by this change in scsi debug code, usb transport code and in
the USB ENE card reader driver.
 Please answer my question about how a SCSI LLD should report residual 
overflows. I think this patch is incompatible with the approach used by 
the SRP initiator driver:

if (unlikely(rsp->flags & SRP_RSP_FLAG_DIUNDER))
	scsi_set_resid(scmnd, be32_to_cpu(rsp->data_in_res_cnt));
else if (unlikely(rsp->flags & SRP_RSP_FLAG_DIOVER))
	scsi_set_resid(scmnd, -be32_to_cpu(rsp->data_in_res_cnt));
else if (unlikely(rsp->flags & SRP_RSP_FLAG_DOUNDER))
	scsi_set_resid(scmnd, be32_to_cpu(rsp->data_out_res_cnt));
else if (unlikely(rsp->flags & SRP_RSP_FLAG_DOOVER))
	scsi_set_resid(scmnd, -be32_to_cpu(rsp->data_out_res_cnt));

Thanks,

Bart.