linux-kernel - Re: [PATCH v2 1/2] cxl/cdat: Handle cdat table build errors

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Date: Wed, 20 Dec 2023 11:55:33 -0800
From: Ira Weiny <ira.weiny@...el.com>
To: fan <nifan.cxl@...il.com>, Ira Weiny <ira.weiny@...el.com>
CC: Jonathan Cameron <jonathan.cameron@...wei.com>, Fan Ni
	<nifan.cxl@...il.com>, Dave Jiang <dave.jiang@...el.com>,
	<linux-cxl@...r.kernel.org>, <linux-kernel@...r.kernel.org>, Huai-Cheng Kuo
	<hchkuo@...ry-design.com.tw>
Subject: Re: [PATCH v2 1/2] cxl/cdat: Handle cdat table build errors

fan wrote:
> On Wed, Nov 29, 2023 at 05:33:03PM -0800, Ira Weiny wrote:
> > The callback for building CDAT tables may return negative error codes.
> > This was previously unhandled and will result in potentially huge
> > allocations later on in ct3_build_cdat()
> > 
> > Detect the negative error code and defer cdat building.
> > 
> > Fixes: f5ee7413d592 ("hw/mem/cxl-type3: Add CXL CDAT Data Object Exchange")
> > Cc: Huai-Cheng Kuo <hchkuo@...ry-design.com.tw>
> > Reviewed-by: Dave Jiang <dave.jiang@...el.com>
> > Signed-off-by: Ira Weiny <ira.weiny@...el.com>
> > ---
> >  hw/cxl/cxl-cdat.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> > 
> > diff --git a/hw/cxl/cxl-cdat.c b/hw/cxl/cxl-cdat.c
> > index 639a2db3e17b..24829cf2428d 100644
> > --- a/hw/cxl/cxl-cdat.c
> > +++ b/hw/cxl/cxl-cdat.c
> > @@ -63,7 +63,7 @@ static void ct3_build_cdat(CDATObject *cdat, Error **errp)
> >      cdat->built_buf_len = cdat->build_cdat_table(&cdat->built_buf,
> >                                                   cdat->private);
> >  
> > -    if (!cdat->built_buf_len) {
> > +    if (cdat->built_buf_len <= 0) {
> >          /* Build later as not all data available yet */
> >          cdat->to_update = true;
> >          return;
> > 
> 
> The fix looks good to me. Just curious how to really build cdat table
> again when an error occurs, for example, the memory allocation fails.

I did not go that far as I am unsure as well.

Ira