linux-kernel - Re: [PATCH] tpm_crb: fix mapping of the buffers

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Message-ID: <20160419170953.GB20844@obsidianresearch.com>
Date:	Tue, 19 Apr 2016 11:09:53 -0600
From:	Jason Gunthorpe <jgunthorpe@...idianresearch.com>
To:	Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>
Cc:	Peter Huewe <peterhuewe@....de>,
	linux-security-module@...r.kernel.org, stable@...r.kernel.org,
	Marcel Selhorst <tpmdd@...horst.net>,
	"moderated list:TPM DEVICE DRIVER" 
	<tpmdd-devel@...ts.sourceforge.net>,
	open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] tpm_crb: fix mapping of the buffers

On Tue, Apr 19, 2016 at 12:54:18PM +0300, Jarkko Sakkinen wrote:
> Cc: stable@...r.kernel.org
> Fixes: 1bd047be37d9 ("tpm_crb: Use devm_ioremap_resource")
> Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>
>  drivers/char/tpm/tpm_crb.c | 39 ++++++++++++++++++++++++++++-----------
>  1 file changed, 28 insertions(+), 11 deletions(-)

This looks OK

Reviewed-by: Jason Gunthorpe <jgunthorpe@...idianresearch.com>

> +	if (cmd_pa != rsp_pa) {
> +		priv->rsp = crb_map_res(dev, priv, &io_res, rsp_pa, rsp_size);
> +		return PTR_ERR_OR_ZERO(priv->rsp);
> +	}

I would use an else here, 'exit on success' is considered an
anti-pattern.

Eg:

if (cmd_pa == rsp_pa) {
	/* According to the PTP specification, overlapping command and response
	 * buffer sizes must be identical.
	 */
	if (cmd_size != rsp_size) {
		dev_err(dev, FW_BUG "overlapping command and response buffer sizes are not identical");
		return -EINVAL;
	}
	priv->rsp = priv->cmd;
}
else {
	priv->rsp = crb_map_res(dev, priv, &io_res, rsp_pa, rsp_size);
        if (IS_ERR(priv->rsp))
	   	return PTR_ERR(priv->rsp);
}

return 0;


Jason