[SCSI] Fix printing of failed 32-byte commands

Having the large CDB allocation logic in sd.c means that
scsi_io_completion does not have access to the command buffer. That in
turn causes garbage to be printed when a 32-byte command fails. Move the
command printing to sd_done where the command buffer is intact.  Clear
the command buffer pointer after the extended CDB has been freed.

Make scsi_print_command ignore commands with NULL CDB pointers to
inhibit printing of garbled command strings.
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>
Reviewed-by: NBoaz Harrosh <bharrosh@panasas.com>
Signed-off-by: NJames Bottomley <James.Bottomley@suse.de>

drivers/scsi/constants.c

@@ -346,6 +346,9 @@ void scsi_print_command(struct scsi_cmnd *cmd)
 {
 	int k;
 
+	if (cmd->cmnd == NULL)
+		return;
+
 	scmd_printk(KERN_INFO, cmd, "CDB: ");
 	print_opcode_name(cmd->cmnd, cmd->cmd_len);
 

drivers/scsi/sd.c

@@ -1209,8 +1209,19 @@ static int sd_done(struct scsi_cmnd *SCpnt)
 		sd_dif_complete(SCpnt, good_bytes);
 
 	if (scsi_host_dif_capable(sdkp->device->host, sdkp->protection_type)
-	    == SD_DIF_TYPE2_PROTECTION && SCpnt->cmnd != SCpnt->request->cmd)
+	    == SD_DIF_TYPE2_PROTECTION && SCpnt->cmnd != SCpnt->request->cmd) {
+
+		/* We have to print a failed command here as the
+		 * extended CDB gets freed before scsi_io_completion()
+		 * is called.
+		 */
+		if (result)
+			scsi_print_command(SCpnt);
+
 		mempool_free(SCpnt->cmnd, sd_cdb_pool);
+		SCpnt->cmnd = NULL;
+		SCpnt->cmd_len = 0;
+	}
 
 	return good_bytes;
 }