Re: [PATCH 7/9] IB/srp: Avoid triggering an infinite loop if memory mapping fails

[Sagi Grimberg <sagig-LDSdmyG8hGV8YrgS2mwiifqBs+8SCbDb@public.gmane.org>]

On 5/6/2014 3:55 PM, Bart Van Assche wrote:
> Only request the SCSI mid-layer to retry a SCSI command after a
> temporary mapping failure (-ENOMEM) but not after a permanent
> mapping failure. This patch avoids that SCSI commands are retried
> indefinitely if a permanent memory mapping failure occurs.
>
> Signed-off-by: Bart Van Assche <bvanassche-HInyCGIudOg@public.gmane.org>
> Cc: Roland Dreier <roland-BHEL68pLQRGGvPXPguhicg@public.gmane.org>
> Cc: David Dillow <dave-i1Mk8JYDVaaSihdK6806/g@public.gmane.org>
> Cc: Sagi Grimberg <sagig-VPRAkNaXOzVWk0Htik3J/w@public.gmane.org>
> Cc: Vu Pham <vu-VPRAkNaXOzVWk0Htik3J/w@public.gmane.org>
> Cc: Sebastian Parschauer <sebastian.riemer-EIkl63zCoXaH+58JC4qpiA@public.gmane.org>
> ---
>   drivers/infiniband/ulp/srp/ib_srp.c | 19 ++++++++++++-------
>   1 file changed, 12 insertions(+), 7 deletions(-)
>
> diff --git a/drivers/infiniband/ulp/srp/ib_srp.c b/drivers/infiniband/ulp/srp/ib_srp.c
> index 1c4b0d3..af94381 100644
> --- a/drivers/infiniband/ulp/srp/ib_srp.c
> +++ b/drivers/infiniband/ulp/srp/ib_srp.c
> @@ -1564,7 +1564,7 @@ static int srp_queuecommand(struct Scsi_Host *shost, struct scsi_cmnd *scmnd)
>   	struct srp_cmd *cmd;
>   	struct ib_device *dev;
>   	unsigned long flags;
> -	int len, result;
> +	int len, result, ret = SCSI_MLQUEUE_HOST_BUSY;
>   	const bool in_scsi_eh = !in_interrupt() && current == shost->ehandler;
>   
>   	/*
> @@ -1580,6 +1580,7 @@ static int srp_queuecommand(struct Scsi_Host *shost, struct scsi_cmnd *scmnd)
>   	if (unlikely(result)) {
>   		scmnd->result = result;
>   		scmnd->scsi_done(scmnd);
> +		ret = 0;
>   		goto unlock_rport;
>   	}
>   
> @@ -1613,7 +1614,12 @@ static int srp_queuecommand(struct Scsi_Host *shost, struct scsi_cmnd *scmnd)
>   	len = srp_map_data(scmnd, target, req);
>   	if (len < 0) {
>   		shost_printk(KERN_ERR, target->scsi_host,
> -			     PFX "Failed to map data\n");
> +			     PFX "Failed to map data (%d)\n", len);
> +		if (len != -ENOMEM) {
> +			scmnd->result = DID_ERROR << 16;
> +			scmnd->scsi_done(scmnd);
> +			ret = 0;
> +		}
>   		goto err_iu;
>   	}
>   
> @@ -1625,11 +1631,13 @@ static int srp_queuecommand(struct Scsi_Host *shost, struct scsi_cmnd *scmnd)
>   		goto err_unmap;
>   	}
>   
> +	ret = 0;
> +
>   unlock_rport:
>   	if (in_scsi_eh)
>   		mutex_unlock(&rport->mutex);
>   
> -	return 0;
> +	return ret;
>   
>   err_unmap:
>   	srp_unmap_data(scmnd, target, req);
> @@ -1643,10 +1651,7 @@ err_iu:
>   err_unlock:
>   	spin_unlock_irqrestore(&target->lock, flags);
>   
> -	if (in_scsi_eh)
> -		mutex_unlock(&rport->mutex);
> -
> -	return SCSI_MLQUEUE_HOST_BUSY;
> +	goto unlock_rport;
>   }
>   
>   /*
Looks good.

Reviewed-by: Sagi Grimberg <sagig-VPRAkNaXOzVWk0Htik3J/w@public.gmane.org>
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