linux-kernel - Re: [PATCH 2/2 v2] cxl/region: Use cond_guard() in show

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Date: Mon, 5 Feb 2024 10:13:31 -0700
From: Dave Jiang <dave.jiang@...el.com>
To: "Fabio M. De Francesco" <fabio.maria.de.francesco@...ux.intel.com>,
 Peter Zijlstra <peterz@...radead.org>,
 Dan Williams <dan.j.williams@...el.com>, linux-kernel@...r.kernel.org
Cc: linux-cxl@...r.kernel.org, Ingo Molnar <mingo@...nel.org>,
 Jonathan Cameron <Jonathan.Cameron@...wei.com>,
 Ira Weiny <ira.weiny@...el.com>
Subject: Re: [PATCH 2/2 v2] cxl/region: Use cond_guard() in show_targetN()



On 2/5/24 7:26 AM, Fabio M. De Francesco wrote:
> Use cond_guard() in show_target() to not open code an up_read() in an 'out'
> block. If the down_read_interruptible() fails, the statement passed to the
> second argument of cond_guard() returns -EINTR.
> 
> Cc: Peter Zijlstra <peterz@...radead.org>
> Suggested-by: Dan Williams <dan.j.williams@...el.com>
> Suggested-by: Ira Weiny <ira.weiny@...el.com>
> Reviewed-by: Jonathan Cameron <Jonathan.Cameron@...wei.com>
> Signed-off-by: Fabio M. De Francesco <fabio.maria.de.francesco@...ux.intel.com>
> ---
>  drivers/cxl/core/region.c | 16 ++++------------
>  1 file changed, 4 insertions(+), 12 deletions(-)
> 
> diff --git a/drivers/cxl/core/region.c b/drivers/cxl/core/region.c
> index 0f05692bfec3..bd3236786a25 100644
> --- a/drivers/cxl/core/region.c
> +++ b/drivers/cxl/core/region.c
> @@ -666,28 +666,20 @@ static size_t show_targetN(struct cxl_region *cxlr, char *buf, int pos)
>  {
>  	struct cxl_region_params *p = &cxlr->params;
>  	struct cxl_endpoint_decoder *cxled;
> -	int rc;
>  
> -	rc = down_read_interruptible(&cxl_region_rwsem);
> -	if (rc)
> -		return rc;
> +	cond_guard(rwsem_read_intr, return -EINTR, &cxl_region_rwsem);
>  
>  	if (pos >= p->interleave_ways) {
>  		dev_dbg(&cxlr->dev, "position %d out of range %d\n", pos,
>  			p->interleave_ways);
> -		rc = -ENXIO;
> -		goto out;
> +		return -ENXIO;
>  	}
>  
>  	cxled = p->targets[pos];
>  	if (!cxled)
> -		rc = sysfs_emit(buf, "\n");
> +		return sysfs_emit(buf, "\n");
>  	else

This else isn't needed because your if statement above returns. I think if you run checkpatch it should've flagged this.

> -		rc = sysfs_emit(buf, "%s\n", dev_name(&cxled->cxld.dev));
> -out:
> -	up_read(&cxl_region_rwsem);
> -
> -	return rc;
> +		return sysfs_emit(buf, "%s\n", dev_name(&cxled->cxld.dev));
>  }
>  
>  static int match_free_decoder(struct device *dev, void *data)