linux-kernel - Re: [PATCH v2 2/3] ntb_transport: Check the number of spads the hardware supports

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Date:	Tue, 7 Jun 2016 17:24:29 +0000
From:	"Jiang, Dave" <dave.jiang@...el.com>
To:	"logang@...tatee.com" <logang@...tatee.com>,
	"jdmason@...zu.us" <jdmason@...zu.us>
CC:	"Allen.Hubbe@....com" <Allen.Hubbe@....com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"sudipm.mukherjee@...il.com" <sudipm.mukherjee@...il.com>,
	"arnd@...db.de" <arnd@...db.de>,
	"john.kading@...ms.com" <john.kading@...ms.com>,
	"linux-ntb@...glegroups.com" <linux-ntb@...glegroups.com>
Subject: Re: [PATCH v2 2/3] ntb_transport: Check the number of spads the
 hardware supports

On Tue, 2016-06-07 at 11:20 -0600, Logan Gunthorpe wrote:
> I'm working on hardware that currently has a limited number of
> scratchpad registers and ntb_ndev fails with no clue as to why. I
> feel it is better to fail early and provide a reasonable error
> message
> then to fail later on.
> 
> The same is done to ntb_perf, but it doesn't currently require enough
> spads to actually fail. I've also removed the unused SPAD_MSG and
> SPAD_ACK enums so that MAX_SPAD accurately reflects the number of
> spads used.
> 
> Signed-off-by: Logan Gunthorpe <logang@...tatee.com>

Acked-by: Dave Jiang <dave.jiang@...el.com>

> ---
>  drivers/ntb/ntb_transport.c | 9 +++++++--
>  drivers/ntb/test/ntb_perf.c | 8 ++++++--
>  2 files changed, 13 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/ntb/ntb_transport.c
> b/drivers/ntb/ntb_transport.c
> index 2ef9d913..6d9940a 100644
> --- a/drivers/ntb/ntb_transport.c
> +++ b/drivers/ntb/ntb_transport.c
> @@ -1037,6 +1037,13 @@ static int ntb_transport_probe(struct
> ntb_client *self, struct ntb_dev *ndev)
>  	int node;
>  	int rc, i;
>  
> +	mw_count = ntb_mw_count(ndev);
> +	if (ntb_spad_count(ndev) < (NUM_MWS + 1 + mw_count * 2)) {
> +		dev_err(&ndev->dev, "Not enough scratch pad
> registers for %s",
> +			NTB_TRANSPORT_NAME);
> +		return -EIO;
> +	}
> +
>  	if (ntb_db_is_unsafe(ndev))
>  		dev_dbg(&ndev->dev,
>  			"doorbell is unsafe, proceed anyway...\n");
> @@ -1052,8 +1059,6 @@ static int ntb_transport_probe(struct
> ntb_client *self, struct ntb_dev *ndev)
>  
>  	nt->ndev = ndev;
>  
> -	mw_count = ntb_mw_count(ndev);
> -
>  	nt->mw_count = mw_count;
>  
>  	nt->mw_vec = kzalloc_node(mw_count * sizeof(*nt->mw_vec),
> diff --git a/drivers/ntb/test/ntb_perf.c
> b/drivers/ntb/test/ntb_perf.c
> index 30635c8..4368519 100644
> --- a/drivers/ntb/test/ntb_perf.c
> +++ b/drivers/ntb/test/ntb_perf.c
> @@ -143,8 +143,6 @@ enum {
>  	VERSION = 0,
>  	MW_SZ_HIGH,
>  	MW_SZ_LOW,
> -	SPAD_MSG,
> -	SPAD_ACK,
>  	MAX_SPAD
>  };
>  
> @@ -696,6 +694,12 @@ static int perf_probe(struct ntb_client *client,
> struct ntb_dev *ntb)
>  	int node;
>  	int rc = 0;
>  
> +	if (ntb_spad_count(ntb) < MAX_SPAD) {
> +		dev_err(&ntb->dev, "Not enough scratch pad registers
> for %s",
> +			DRIVER_NAME);
> +		return -EIO;
> +	}
> +
>  	node = dev_to_node(&pdev->dev);
>  
>  	perf = kzalloc_node(sizeof(*perf), GFP_KERNEL, node);
> -- 
> 2.1.4
>