[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: Martin K. Petersen <martin.petersen@oracle.com>
Reviewed-by: Boaz Harrosh <bharrosh@panasas.com>
Signed-off-by: James Bottomley <James.Bottomley@suse.de>
diff --git a/drivers/scsi/constants.c b/drivers/scsi/constants.c
index 7092ff6..cd05e04 100644
--- a/drivers/scsi/constants.c
+++ b/drivers/scsi/constants.c
@@ -346,6 +346,9 @@
 {
 	int k;
 
+	if (cmd->cmnd == NULL)
+		return;
+
 	scmd_printk(KERN_INFO, cmd, "CDB: ");
 	print_opcode_name(cmd->cmnd, cmd->cmd_len);