This patch (as1036) causes the SCSI midlayer to take into account the
residue value provided by some low-level drivers. There's at least
one situation (USB mass storage with the Bulk-only transport) where
the specification states that it is permissible for a device to
indicate some of the data was not transferred correctly merely by
setting the residue value, without issuing a Check Condition.
Signed-off-by: Alan Stern <stern@xxxxxxxxxxxxxxxxxxx>
CC: Boaz Harrosh <bharrosh@xxxxxxxxxxx>
---
Index: usb-2.6/drivers/scsi/scsi.c
===================================================================
--- usb-2.6.orig/drivers/scsi/scsi.c
+++ usb-2.6/drivers/scsi/scsi.c
@@ -732,6 +732,7 @@ void scsi_finish_command(struct scsi_cmn
struct Scsi_Host *shost = sdev->host;
struct scsi_driver *drv;
unsigned int good_bytes;
+ unsigned int non_residue_bytes;
scsi_device_unbusy(sdev);
@@ -758,11 +759,16 @@ void scsi_finish_command(struct scsi_cmn
"(result %x)\n", cmd->result));
good_bytes = scsi_bufflen(cmd);
+ non_residue_bytes = good_bytes - scsi_get_resid(cmd);
if (cmd->request->cmd_type != REQ_TYPE_BLOCK_PC) {
drv = scsi_cmd_to_driver(cmd);
if (drv->done)
good_bytes = drv->done(cmd);
}
+
+ /* If the device sent a meaningful residue, accept it. */
+ if (unlikely(non_residue_bytes < good_bytes))
+ good_bytes = non_residue_bytes;
scsi_io_completion(cmd, good_bytes);
}
EXPORT_SYMBOL(scsi_finish_command);
-
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