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[1/4] drm/i915/gt: GEM_BUG_ON unexpected NULL at scatterlist walking

Message ID 20220421113813.30796-2-ramalingam.c@intel.com (mailing list archive)
State New, archived
Headers show
Series Flat-CCS eviction enhancements | expand

Commit Message

Ramalingam C April 21, 2022, 11:38 a.m. UTC
While locating the start of ccs scatterlist in smem scatterlist, that has
to be the size of lmem obj size + corresponding ccs data size. Report bug
if scatterlist terminate before that length.

Signed-off-by: Ramalingam C <ramalingam.c@intel.com>
---
 drivers/gpu/drm/i915/gt/intel_migrate.c | 6 ++++++
 1 file changed, 6 insertions(+)

Comments

Hellstrom, Thomas April 21, 2022, 1:27 p.m. UTC | #1
On Thu, 2022-04-21 at 17:08 +0530, Ramalingam C wrote:
> While locating the start of ccs scatterlist in smem scatterlist, that
> has
> to be the size of lmem obj size + corresponding ccs data size. Report
> bug
> if scatterlist terminate before that length.
> 
> Signed-off-by: Ramalingam C <ramalingam.c@intel.com>
> ---
>  drivers/gpu/drm/i915/gt/intel_migrate.c | 6 ++++++
>  1 file changed, 6 insertions(+)
> 
> diff --git a/drivers/gpu/drm/i915/gt/intel_migrate.c
> b/drivers/gpu/drm/i915/gt/intel_migrate.c
> index 9d552f30b627..29d761da02c4 100644
> --- a/drivers/gpu/drm/i915/gt/intel_migrate.c
> +++ b/drivers/gpu/drm/i915/gt/intel_migrate.c
> @@ -687,6 +687,12 @@ static void get_ccs_sg_sgt(struct sgt_dma *it,
> u32 bytes_to_cpy)
>                 bytes_to_cpy -= len;
>  


>                 it->sg = __sg_next(it->sg);

If bytes_to_cpy == 0 here, couldn't it->sg be NULL then?

> +
> +               /*
> +                * scatterlist supposed to be the size of
> +                * bytes_to_cpy + GET_CCS_BYTES(bytes_to_copy).
> +                */
> +               GEM_BUG_ON(!it->sg);
>                 it->dma = sg_dma_address(it->sg);
>                 it->max = it->dma + sg_dma_len(it->sg);
>         } while (bytes_to_cpy);

/Thomas
Ramalingam C April 21, 2022, 2:04 p.m. UTC | #2
On 2022-04-21 at 18:57:59 +0530, Hellstrom, Thomas wrote:
> On Thu, 2022-04-21 at 17:08 +0530, Ramalingam C wrote:
> > While locating the start of ccs scatterlist in smem scatterlist, that
> > has
> > to be the size of lmem obj size + corresponding ccs data size. Report
> > bug
> > if scatterlist terminate before that length.
> >
> > Signed-off-by: Ramalingam C <ramalingam.c@intel.com>
> > ---
> >  drivers/gpu/drm/i915/gt/intel_migrate.c | 6 ++++++
> >  1 file changed, 6 insertions(+)
> >
> > diff --git a/drivers/gpu/drm/i915/gt/intel_migrate.c
> > b/drivers/gpu/drm/i915/gt/intel_migrate.c
> > index 9d552f30b627..29d761da02c4 100644
> > --- a/drivers/gpu/drm/i915/gt/intel_migrate.c
> > +++ b/drivers/gpu/drm/i915/gt/intel_migrate.c
> > @@ -687,6 +687,12 @@ static void get_ccs_sg_sgt(struct sgt_dma *it,
> > u32 bytes_to_cpy)
> >                 bytes_to_cpy -= len;
> >
> 
> 
> >                 it->sg = __sg_next(it->sg);
> 
> If bytes_to_cpy == 0 here, couldn't it->sg be NULL then?
Hi,

bytes_to_cpy is the lmem size and the scatterlist is the length of
bytes_to_cpy + GET_CCS_BYTES(bytes_to_cpy). So this should not be null.

when bytes_to_cpy reduces to zero we will be having the start of the scatterlist
for ccs.

Ram.
> 
> > +
> > +               /*
> > +                * scatterlist supposed to be the size of
> > +                * bytes_to_cpy + GET_CCS_BYTES(bytes_to_copy).
> > +                */
> > +               GEM_BUG_ON(!it->sg);
> >                 it->dma = sg_dma_address(it->sg);
> >                 it->max = it->dma + sg_dma_len(it->sg);
> >         } while (bytes_to_cpy);
> 
> /Thomas
>
diff mbox series

Patch

diff --git a/drivers/gpu/drm/i915/gt/intel_migrate.c b/drivers/gpu/drm/i915/gt/intel_migrate.c
index 9d552f30b627..29d761da02c4 100644
--- a/drivers/gpu/drm/i915/gt/intel_migrate.c
+++ b/drivers/gpu/drm/i915/gt/intel_migrate.c
@@ -687,6 +687,12 @@  static void get_ccs_sg_sgt(struct sgt_dma *it, u32 bytes_to_cpy)
 		bytes_to_cpy -= len;
 
 		it->sg = __sg_next(it->sg);
+
+		/*
+		 * scatterlist supposed to be the size of
+		 * bytes_to_cpy + GET_CCS_BYTES(bytes_to_copy).
+		 */
+		GEM_BUG_ON(!it->sg);
 		it->dma = sg_dma_address(it->sg);
 		it->max = it->dma + sg_dma_len(it->sg);
 	} while (bytes_to_cpy);