On Wed, 2017-06-07 at 14:43 -0700, Himanshu Madhani wrote:
> +enum {
> + TYPE_SRB,
> + TYPE_TGT_CMD,
> +};
> +
> typedef struct srb {
> + /*
> + * Do not move cmd_type field, it needs to
> + * line up with qla_tgt_cmd->cmd_type
> + */
> + uint8_t cmd_type;
> + uint8_t pad[3];
> atomic_t ref_count;
> struct fc_port *fcport;
> struct scsi_qla_host *vha;
[ ... ]
> struct qla_tgt_cmd {
> + /*
> + * Do not move cmd_type field. it needs to line up with srb->cmd_type
> + */
> + uint8_t cmd_type;
> + uint8_t pad[7];
> struct se_cmd se_cmd;
> struct fc_port *sess;
> int state;
Hello Quinn and Himanshu,
Sorry but this is really inelegant. Have you considered the following?
- Keep the existing srb and qla_tgt_cmd data structures.
- Introduce a new data structure with enum cmd_type as the first member and
a union of struct srb and struct qla_tgt_cmd as the second member.
- Use __attribute__((aligned(...))) to express alignment requirements instead
of explicitly inserting padding bytes.
With that approach no casts are needed to convert a pointer to the new data
structure into a struct srb or struct qla_tgt_cmd pointer - all that will be
needed is to take the address of the appropriate member of the union.
Thanks,
Bart.
