On Fri, Sep 17, 2021 at 05:04:44PM -0700, Bart Van Assche wrote:
> Conditional statements are faster than indirect calls. Use a member variable
> to track the SCSI command submitter such that later patches can call
> scsi_done(scmd) instead of scmd->scsi_done(scmd).
>
> The asymmetric behavior that scsi_send_eh_cmnd() sets the submission
> context to the SCSI error handler and that it does not restore the
> submission context to the SCSI core is retained.
>
> Cc: Hannes Reinecke <hare@xxxxxxxx>
> Cc: Ming Lei <ming.lei@xxxxxxxxxx>
> Cc: Christoph Hellwig <hch@xxxxxx>
> Signed-off-by: Bart Van Assche <bvanassche@xxxxxxx>
> ---
> drivers/scsi/scsi_error.c | 18 +++++++-----------
> drivers/scsi/scsi_lib.c | 9 +++++++++
> drivers/scsi/scsi_priv.h | 1 +
> include/scsi/scsi_cmnd.h | 7 +++++++
> 4 files changed, 24 insertions(+), 11 deletions(-)
>
> diff --git a/include/scsi/scsi_cmnd.h b/include/scsi/scsi_cmnd.h
> index eaf04c9a1dfc..365d47a66c18 100644
> --- a/include/scsi/scsi_cmnd.h
> +++ b/include/scsi/scsi_cmnd.h
> @@ -65,6 +65,12 @@ struct scsi_pointer {
> #define SCMD_STATE_COMPLETE 0
> #define SCMD_STATE_INFLIGHT 1
>
> +enum scsi_cmnd_submitter {
> + BLOCK_LAYER = 0,
> + SCSI_ERROR_HANDLER = 1,
> + SCSI_RESET_IOCTL = 2,
> +} __packed;
> +
Might be prudent to not make them as generic, especially `BLOCK_LAYER`
might easily clash without namespace. `SUBMITTED_BY_...`?
> struct scsi_cmnd {
> struct scsi_request req;
> struct scsi_device *device;
> @@ -90,6 +96,7 @@ struct scsi_cmnd {
> unsigned char prot_op;
> unsigned char prot_type;
> unsigned char prot_flags;
> + enum scsi_cmnd_submitter submitter;
Do you think it'd make much of a difference, if you initialized this in
scsi_init_command(), or somewhere around there, explicitly to
`BLOCK_LAYER`? Makes it easier to maintain, and to not forget, that it
needs to be done, if the memset() to 0 ever changes... after the
memset() the memory should be hot.
I just had to search a bit where this gets set to 0, as I didn't
remember exactly where it was.
>
> unsigned short cmd_len;
> enum dma_data_direction sc_data_direction;
--
Best Regards, Benjamin Block / Linux on IBM Z Kernel Development / IBM Systems
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