On Mon, 2015-08-10 at 12:09 -0500, Matthew R. Ochs wrote:
> Introduce support for enhanced I/O error handling.
>
> Signed-off-by: Matthew R. Ochs <mro...@linux.vnet.ibm.com>
> Signed-off-by: Manoj N. Kumar <ma...@linux.vnet.ibm.com>
> ---
So I'm not necessarily very qualified to review SCSI bits as I haven't
done anything close to the Linux SCSI code for almost a decade but I
have a couple of questions and nits...
> wait_queue_head_t tmf_waitq;
> bool tmf_active;
> - u8 err_recovery_active:1;
> + wait_queue_head_t limbo_waitq;
> + enum cxlflash_state state;
> };
>
> struct afu_cmd {
> diff --git a/drivers/scsi/cxlflash/main.c b/drivers/scsi/cxlflash/main.c
> index 76a7286..18359d4 100644
> --- a/drivers/scsi/cxlflash/main.c
> +++ b/drivers/scsi/cxlflash/main.c
> @@ -380,6 +380,18 @@ static int cxlflash_queuecommand(struct Scsi_Host *host,
> struct scsi_cmnd *scp)
> }
> spin_unlock_irqrestore(&cfg->tmf_waitq.lock, lock_flags);
>
> + switch (cfg->state) {
> + case STATE_LIMBO:
> + pr_debug_ratelimited("%s: device in limbo!\n", __func__);
> + rc = SCSI_MLQUEUE_HOST_BUSY;
> + goto out;
> + case STATE_FAILTERM:
> + pr_debug_ratelimited("%s: device has failed!\n", __func__);
> + goto error;
> + default:
> + break;
> + }
I noticed that you mostly read and write that new state outside of your
tmf_waitq.lock. Is there any other lock or mutex protecting you ? In
this specific case ?
I know in the old day queuecommand was called with a host lock, is that
still the case ?
Or you just don't care about an occasional spurrious
SCSI_MLQUEUE_HOST_BUSY ?
> cmd = cxlflash_cmd_checkout(afu);
> if (unlikely(!cmd)) {
> pr_err("%s: could not get a free command\n", __func__);
> @@ -428,6 +440,10 @@ static int cxlflash_queuecommand(struct Scsi_Host *host,
> struct scsi_cmnd *scp)
>
> out:
> return rc;
> +error:
> + scp->result = (DID_NO_CONNECT << 16);
> + scp->scsi_done(scp);
> + return 0;
> }
>
> /**
> @@ -455,9 +471,21 @@ static int cxlflash_eh_device_reset_handler(struct
> scsi_cmnd *scp)
> get_unaligned_be32(&((u32 *)scp->cmnd)[2]),
> get_unaligned_be32(&((u32 *)scp->cmnd)[3]));
>
> - rcr = send_tmf(afu, scp, TMF_LUN_RESET);
> - if (unlikely(rcr))
> + switch (cfg->state) {
> + case STATE_NORMAL:
> + rcr = send_tmf(afu, scp, TMF_LUN_RESET);
> + if (unlikely(rcr))
> + rc = FAILED;
> + break;
> + case STATE_LIMBO:
> + wait_event(cfg->limbo_waitq, cfg->state != STATE_LIMBO);
> + if (cfg->state == STATE_NORMAL)
> + break;
> + /* fall through */
> + default:
> rc = FAILED;
> + break;
> + }
Same here, since you are doing wait_event, I assume no lock is held
(unless it's a mutex) and in subsequent places I am not listing.
As I said, it could well be that it all works fine but it would be worth
mentioning in this case because it's not obvious from simply reading the
code.
Cheers,
Ben.
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