| Message ID | 20200826063316.23486-9-m.szyprowski@samsung.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | DRM: fix struct sg_table nents vs. orig_nents misuse | expand |
On 2020-08-26 07:32, Marek Szyprowski wrote: > The Documentation/DMA-API-HOWTO.txt states that the dma_map_sg() function > returns the number of the created entries in the DMA address space. > However the subsequent calls to the dma_sync_sg_for_{device,cpu}() and > dma_unmap_sg must be called with the original number of the entries > passed to the dma_map_sg(). > > struct sg_table is a common structure used for describing a non-contiguous > memory buffer, used commonly in the DRM and graphics subsystems. It > consists of a scatterlist with memory pages and DMA addresses (sgl entry), > as well as the number of scatterlist entries: CPU pages (orig_nents entry) > and DMA mapped pages (nents entry). > > It turned out that it was a common mistake to misuse nents and orig_nents > entries, calling DMA-mapping functions with a wrong number of entries or > ignoring the number of mapped entries returned by the dma_map_sg() > function. > > This driver creatively uses sg_table->orig_nents to store the size of the > allocated scatterlist and ignores the number of the entries returned by > dma_map_sg function. The sg_table->orig_nents is (mis)used to properly > free the (over)allocated scatterlist. > > This patch only introduces the common DMA-mapping wrappers operating > directly on the struct sg_table objects to the dmabuf related functions, > so the other drivers, which might share buffers with i915 could rely on > the properly set nents and orig_nents values. This one looks mechanical enough :) Reviewed-by: Robin Murphy <robin.murphy@arm.com> > Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com> > --- > drivers/gpu/drm/i915/gem/i915_gem_dmabuf.c | 11 +++-------- > drivers/gpu/drm/i915/gem/selftests/mock_dmabuf.c | 7 +++---- > 2 files changed, 6 insertions(+), 12 deletions(-) > > diff --git a/drivers/gpu/drm/i915/gem/i915_gem_dmabuf.c b/drivers/gpu/drm/i915/gem/i915_gem_dmabuf.c > index 2679380159fc..8a988592715b 100644 > --- a/drivers/gpu/drm/i915/gem/i915_gem_dmabuf.c > +++ b/drivers/gpu/drm/i915/gem/i915_gem_dmabuf.c > @@ -48,12 +48,9 @@ static struct sg_table *i915_gem_map_dma_buf(struct dma_buf_attachment *attachme > src = sg_next(src); > } > > - if (!dma_map_sg_attrs(attachment->dev, > - st->sgl, st->nents, dir, > - DMA_ATTR_SKIP_CPU_SYNC)) { > - ret = -ENOMEM; > + ret = dma_map_sgtable(attachment->dev, st, dir, DMA_ATTR_SKIP_CPU_SYNC); > + if (ret) > goto err_free_sg; > - } > > return st; > > @@ -73,9 +70,7 @@ static void i915_gem_unmap_dma_buf(struct dma_buf_attachment *attachment, > { > struct drm_i915_gem_object *obj = dma_buf_to_obj(attachment->dmabuf); > > - dma_unmap_sg_attrs(attachment->dev, > - sg->sgl, sg->nents, dir, > - DMA_ATTR_SKIP_CPU_SYNC); > + dma_unmap_sgtable(attachment->dev, sg, dir, DMA_ATTR_SKIP_CPU_SYNC); > sg_free_table(sg); > kfree(sg); > > diff --git a/drivers/gpu/drm/i915/gem/selftests/mock_dmabuf.c b/drivers/gpu/drm/i915/gem/selftests/mock_dmabuf.c > index debaf7b18ab5..be30b27e2926 100644 > --- a/drivers/gpu/drm/i915/gem/selftests/mock_dmabuf.c > +++ b/drivers/gpu/drm/i915/gem/selftests/mock_dmabuf.c > @@ -28,10 +28,9 @@ static struct sg_table *mock_map_dma_buf(struct dma_buf_attachment *attachment, > sg = sg_next(sg); > } > > - if (!dma_map_sg(attachment->dev, st->sgl, st->nents, dir)) { > - err = -ENOMEM; > + err = dma_map_sgtable(attachment->dev, st, dir, 0); > + if (err) > goto err_st; > - } > > return st; > > @@ -46,7 +45,7 @@ static void mock_unmap_dma_buf(struct dma_buf_attachment *attachment, > struct sg_table *st, > enum dma_data_direction dir) > { > - dma_unmap_sg(attachment->dev, st->sgl, st->nents, dir); > + dma_unmap_sgtable(attachment->dev, st, dir, 0); > sg_free_table(st); > kfree(st); > } >
>-----Original Message----- >From: Intel-gfx <intel-gfx-bounces@lists.freedesktop.org> On Behalf Of >Marek Szyprowski >Sent: Wednesday, August 26, 2020 2:33 AM >To: dri-devel@lists.freedesktop.org; iommu@lists.linux-foundation.org; >linaro-mm-sig@lists.linaro.org; linux-kernel@vger.kernel.org >Cc: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>; David Airlie ><airlied@linux.ie>; intel-gfx@lists.freedesktop.org; Robin Murphy ><robin.murphy@arm.com>; Christoph Hellwig <hch@lst.de>; linux-arm- >kernel@lists.infradead.org; Marek Szyprowski ><m.szyprowski@samsung.com> >Subject: [Intel-gfx] [PATCH v9 08/32] drm: i915: fix common struct sg_table >related issues > >The Documentation/DMA-API-HOWTO.txt states that the dma_map_sg() >function >returns the number of the created entries in the DMA address space. >However the subsequent calls to the dma_sync_sg_for_{device,cpu}() and >dma_unmap_sg must be called with the original number of the entries >passed to the dma_map_sg(). > >struct sg_table is a common structure used for describing a non-contiguous >memory buffer, used commonly in the DRM and graphics subsystems. It >consists of a scatterlist with memory pages and DMA addresses (sgl entry), >as well as the number of scatterlist entries: CPU pages (orig_nents entry) >and DMA mapped pages (nents entry). > >It turned out that it was a common mistake to misuse nents and orig_nents >entries, calling DMA-mapping functions with a wrong number of entries or >ignoring the number of mapped entries returned by the dma_map_sg() >function. > >This driver creatively uses sg_table->orig_nents to store the size of the >allocated scatterlist and ignores the number of the entries returned by >dma_map_sg function. The sg_table->orig_nents is (mis)used to properly >free the (over)allocated scatterlist. > >This patch only introduces the common DMA-mapping wrappers operating >directly on the struct sg_table objects to the dmabuf related functions, >so the other drivers, which might share buffers with i915 could rely on >the properly set nents and orig_nents values. > >Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com> >--- > drivers/gpu/drm/i915/gem/i915_gem_dmabuf.c | 11 +++-------- > drivers/gpu/drm/i915/gem/selftests/mock_dmabuf.c | 7 +++---- > 2 files changed, 6 insertions(+), 12 deletions(-) > >diff --git a/drivers/gpu/drm/i915/gem/i915_gem_dmabuf.c >b/drivers/gpu/drm/i915/gem/i915_gem_dmabuf.c >index 2679380159fc..8a988592715b 100644 >--- a/drivers/gpu/drm/i915/gem/i915_gem_dmabuf.c >+++ b/drivers/gpu/drm/i915/gem/i915_gem_dmabuf.c >@@ -48,12 +48,9 @@ static struct sg_table *i915_gem_map_dma_buf(struct >dma_buf_attachment *attachme > src = sg_next(src); > } > >- if (!dma_map_sg_attrs(attachment->dev, >- st->sgl, st->nents, dir, >- DMA_ATTR_SKIP_CPU_SYNC)) { >- ret = -ENOMEM; You have dropped this error value. Do you now if this is a benign loss? M >+ ret = dma_map_sgtable(attachment->dev, st, dir, >DMA_ATTR_SKIP_CPU_SYNC); >+ if (ret) > goto err_free_sg; >- } > > return st; > >@@ -73,9 +70,7 @@ static void i915_gem_unmap_dma_buf(struct >dma_buf_attachment *attachment, > { > struct drm_i915_gem_object *obj = dma_buf_to_obj(attachment- >>dmabuf); > >- dma_unmap_sg_attrs(attachment->dev, >- sg->sgl, sg->nents, dir, >- DMA_ATTR_SKIP_CPU_SYNC); >+ dma_unmap_sgtable(attachment->dev, sg, dir, >DMA_ATTR_SKIP_CPU_SYNC); > sg_free_table(sg); > kfree(sg); > >diff --git a/drivers/gpu/drm/i915/gem/selftests/mock_dmabuf.c >b/drivers/gpu/drm/i915/gem/selftests/mock_dmabuf.c >index debaf7b18ab5..be30b27e2926 100644 >--- a/drivers/gpu/drm/i915/gem/selftests/mock_dmabuf.c >+++ b/drivers/gpu/drm/i915/gem/selftests/mock_dmabuf.c >@@ -28,10 +28,9 @@ static struct sg_table *mock_map_dma_buf(struct >dma_buf_attachment *attachment, > sg = sg_next(sg); > } > >- if (!dma_map_sg(attachment->dev, st->sgl, st->nents, dir)) { >- err = -ENOMEM; >+ err = dma_map_sgtable(attachment->dev, st, dir, 0); >+ if (err) > goto err_st; >- } > > return st; > >@@ -46,7 +45,7 @@ static void mock_unmap_dma_buf(struct >dma_buf_attachment *attachment, > struct sg_table *st, > enum dma_data_direction dir) > { >- dma_unmap_sg(attachment->dev, st->sgl, st->nents, dir); >+ dma_unmap_sgtable(attachment->dev, st, dir, 0); > sg_free_table(st); > kfree(st); > } >-- >2.17.1 > >_______________________________________________ >Intel-gfx mailing list >Intel-gfx@lists.freedesktop.org >https://lists.freedesktop.org/mailman/listinfo/intel-gfx
On 2020-09-01 20:38, Ruhl, Michael J wrote: >> -----Original Message----- >> From: Intel-gfx <intel-gfx-bounces@lists.freedesktop.org> On Behalf Of >> Marek Szyprowski >> Sent: Wednesday, August 26, 2020 2:33 AM >> To: dri-devel@lists.freedesktop.org; iommu@lists.linux-foundation.org; >> linaro-mm-sig@lists.linaro.org; linux-kernel@vger.kernel.org >> Cc: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>; David Airlie >> <airlied@linux.ie>; intel-gfx@lists.freedesktop.org; Robin Murphy >> <robin.murphy@arm.com>; Christoph Hellwig <hch@lst.de>; linux-arm- >> kernel@lists.infradead.org; Marek Szyprowski >> <m.szyprowski@samsung.com> >> Subject: [Intel-gfx] [PATCH v9 08/32] drm: i915: fix common struct sg_table >> related issues >> >> The Documentation/DMA-API-HOWTO.txt states that the dma_map_sg() >> function >> returns the number of the created entries in the DMA address space. >> However the subsequent calls to the dma_sync_sg_for_{device,cpu}() and >> dma_unmap_sg must be called with the original number of the entries >> passed to the dma_map_sg(). >> >> struct sg_table is a common structure used for describing a non-contiguous >> memory buffer, used commonly in the DRM and graphics subsystems. It >> consists of a scatterlist with memory pages and DMA addresses (sgl entry), >> as well as the number of scatterlist entries: CPU pages (orig_nents entry) >> and DMA mapped pages (nents entry). >> >> It turned out that it was a common mistake to misuse nents and orig_nents >> entries, calling DMA-mapping functions with a wrong number of entries or >> ignoring the number of mapped entries returned by the dma_map_sg() >> function. >> >> This driver creatively uses sg_table->orig_nents to store the size of the >> allocated scatterlist and ignores the number of the entries returned by >> dma_map_sg function. The sg_table->orig_nents is (mis)used to properly >> free the (over)allocated scatterlist. >> >> This patch only introduces the common DMA-mapping wrappers operating >> directly on the struct sg_table objects to the dmabuf related functions, >> so the other drivers, which might share buffers with i915 could rely on >> the properly set nents and orig_nents values. >> >> Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com> >> --- >> drivers/gpu/drm/i915/gem/i915_gem_dmabuf.c | 11 +++-------- >> drivers/gpu/drm/i915/gem/selftests/mock_dmabuf.c | 7 +++---- >> 2 files changed, 6 insertions(+), 12 deletions(-) >> >> diff --git a/drivers/gpu/drm/i915/gem/i915_gem_dmabuf.c >> b/drivers/gpu/drm/i915/gem/i915_gem_dmabuf.c >> index 2679380159fc..8a988592715b 100644 >> --- a/drivers/gpu/drm/i915/gem/i915_gem_dmabuf.c >> +++ b/drivers/gpu/drm/i915/gem/i915_gem_dmabuf.c >> @@ -48,12 +48,9 @@ static struct sg_table *i915_gem_map_dma_buf(struct >> dma_buf_attachment *attachme >> src = sg_next(src); >> } >> >> - if (!dma_map_sg_attrs(attachment->dev, >> - st->sgl, st->nents, dir, >> - DMA_ATTR_SKIP_CPU_SYNC)) { >> - ret = -ENOMEM; > > You have dropped this error value. > > Do you now if this is a benign loss? True, dma_map_sgtable() will return -EINVAL rather than -ENOMEM for failure. A quick look through other .map_dma_buf callbacks suggests they're returning a motley mix of error values and NULL for failure cases, so I'd imagine that importers shouldn't be too sensitive to the exact value. Robin. > > M > >> + ret = dma_map_sgtable(attachment->dev, st, dir, >> DMA_ATTR_SKIP_CPU_SYNC); >> + if (ret) >> goto err_free_sg; >> - } >> >> return st; >> >> @@ -73,9 +70,7 @@ static void i915_gem_unmap_dma_buf(struct >> dma_buf_attachment *attachment, >> { >> struct drm_i915_gem_object *obj = dma_buf_to_obj(attachment- >>> dmabuf); >> >> - dma_unmap_sg_attrs(attachment->dev, >> - sg->sgl, sg->nents, dir, >> - DMA_ATTR_SKIP_CPU_SYNC); >> + dma_unmap_sgtable(attachment->dev, sg, dir, >> DMA_ATTR_SKIP_CPU_SYNC); >> sg_free_table(sg); >> kfree(sg); >> >> diff --git a/drivers/gpu/drm/i915/gem/selftests/mock_dmabuf.c >> b/drivers/gpu/drm/i915/gem/selftests/mock_dmabuf.c >> index debaf7b18ab5..be30b27e2926 100644 >> --- a/drivers/gpu/drm/i915/gem/selftests/mock_dmabuf.c >> +++ b/drivers/gpu/drm/i915/gem/selftests/mock_dmabuf.c >> @@ -28,10 +28,9 @@ static struct sg_table *mock_map_dma_buf(struct >> dma_buf_attachment *attachment, >> sg = sg_next(sg); >> } >> >> - if (!dma_map_sg(attachment->dev, st->sgl, st->nents, dir)) { >> - err = -ENOMEM; >> + err = dma_map_sgtable(attachment->dev, st, dir, 0); >> + if (err) >> goto err_st; >> - } >> >> return st; >> >> @@ -46,7 +45,7 @@ static void mock_unmap_dma_buf(struct >> dma_buf_attachment *attachment, >> struct sg_table *st, >> enum dma_data_direction dir) >> { >> - dma_unmap_sg(attachment->dev, st->sgl, st->nents, dir); >> + dma_unmap_sgtable(attachment->dev, st, dir, 0); >> sg_free_table(st); >> kfree(st); >> } >> -- >> 2.17.1 >> >> _______________________________________________ >> Intel-gfx mailing list >> Intel-gfx@lists.freedesktop.org >> https://lists.freedesktop.org/mailman/listinfo/intel-gfx
>-----Original Message----- >From: Robin Murphy <robin.murphy@arm.com> >Sent: Tuesday, September 1, 2020 3:54 PM >To: Ruhl, Michael J <michael.j.ruhl@intel.com>; Marek Szyprowski ><m.szyprowski@samsung.com>; dri-devel@lists.freedesktop.org; >iommu@lists.linux-foundation.org; linaro-mm-sig@lists.linaro.org; linux- >kernel@vger.kernel.org >Cc: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>; David Airlie ><airlied@linux.ie>; intel-gfx@lists.freedesktop.org; Christoph Hellwig ><hch@lst.de>; linux-arm-kernel@lists.infradead.org >Subject: Re: [Intel-gfx] [PATCH v9 08/32] drm: i915: fix common struct >sg_table related issues > >On 2020-09-01 20:38, Ruhl, Michael J wrote: >>> -----Original Message----- >>> From: Intel-gfx <intel-gfx-bounces@lists.freedesktop.org> On Behalf Of >>> Marek Szyprowski >>> Sent: Wednesday, August 26, 2020 2:33 AM >>> To: dri-devel@lists.freedesktop.org; iommu@lists.linux-foundation.org; >>> linaro-mm-sig@lists.linaro.org; linux-kernel@vger.kernel.org >>> Cc: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>; David Airlie >>> <airlied@linux.ie>; intel-gfx@lists.freedesktop.org; Robin Murphy >>> <robin.murphy@arm.com>; Christoph Hellwig <hch@lst.de>; linux-arm- >>> kernel@lists.infradead.org; Marek Szyprowski >>> <m.szyprowski@samsung.com> >>> Subject: [Intel-gfx] [PATCH v9 08/32] drm: i915: fix common struct sg_table >>> related issues >>> >>> The Documentation/DMA-API-HOWTO.txt states that the dma_map_sg() >>> function >>> returns the number of the created entries in the DMA address space. >>> However the subsequent calls to the dma_sync_sg_for_{device,cpu}() and >>> dma_unmap_sg must be called with the original number of the entries >>> passed to the dma_map_sg(). >>> >>> struct sg_table is a common structure used for describing a non-contiguous >>> memory buffer, used commonly in the DRM and graphics subsystems. It >>> consists of a scatterlist with memory pages and DMA addresses (sgl entry), >>> as well as the number of scatterlist entries: CPU pages (orig_nents entry) >>> and DMA mapped pages (nents entry). >>> >>> It turned out that it was a common mistake to misuse nents and orig_nents >>> entries, calling DMA-mapping functions with a wrong number of entries or >>> ignoring the number of mapped entries returned by the dma_map_sg() >>> function. >>> >>> This driver creatively uses sg_table->orig_nents to store the size of the >>> allocated scatterlist and ignores the number of the entries returned by >>> dma_map_sg function. The sg_table->orig_nents is (mis)used to properly >>> free the (over)allocated scatterlist. >>> >>> This patch only introduces the common DMA-mapping wrappers operating >>> directly on the struct sg_table objects to the dmabuf related functions, >>> so the other drivers, which might share buffers with i915 could rely on >>> the properly set nents and orig_nents values. >>> >>> Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com> >>> --- >>> drivers/gpu/drm/i915/gem/i915_gem_dmabuf.c | 11 +++-------- >>> drivers/gpu/drm/i915/gem/selftests/mock_dmabuf.c | 7 +++---- >>> 2 files changed, 6 insertions(+), 12 deletions(-) >>> >>> diff --git a/drivers/gpu/drm/i915/gem/i915_gem_dmabuf.c >>> b/drivers/gpu/drm/i915/gem/i915_gem_dmabuf.c >>> index 2679380159fc..8a988592715b 100644 >>> --- a/drivers/gpu/drm/i915/gem/i915_gem_dmabuf.c >>> +++ b/drivers/gpu/drm/i915/gem/i915_gem_dmabuf.c >>> @@ -48,12 +48,9 @@ static struct sg_table >*i915_gem_map_dma_buf(struct >>> dma_buf_attachment *attachme >>> src = sg_next(src); >>> } >>> >>> - if (!dma_map_sg_attrs(attachment->dev, >>> - st->sgl, st->nents, dir, >>> - DMA_ATTR_SKIP_CPU_SYNC)) { >>> - ret = -ENOMEM; >> >> You have dropped this error value. >> >> Do you now if this is a benign loss? > >True, dma_map_sgtable() will return -EINVAL rather than -ENOMEM for >failure. A quick look through other .map_dma_buf callbacks suggests >they're returning a motley mix of error values and NULL for failure >cases, so I'd imagine that importers shouldn't be too sensitive to the >exact value. I followed some of our code through to see if anyone is checking for -ENOMEM... I have found in some test paths... However, it is not clear to me if we can get to those paths from here. Anyways, Reviewed-by: Michael J. Ruhl <michael.j.ruhl@intel.com> Mike >Robin. > >> >> M >> >>> + ret = dma_map_sgtable(attachment->dev, st, dir, >>> DMA_ATTR_SKIP_CPU_SYNC); >>> + if (ret) >>> goto err_free_sg; >>> - } >>> >>> return st; >>> >>> @@ -73,9 +70,7 @@ static void i915_gem_unmap_dma_buf(struct >>> dma_buf_attachment *attachment, >>> { >>> struct drm_i915_gem_object *obj = dma_buf_to_obj(attachment- >>>> dmabuf); >>> >>> - dma_unmap_sg_attrs(attachment->dev, >>> - sg->sgl, sg->nents, dir, >>> - DMA_ATTR_SKIP_CPU_SYNC); >>> + dma_unmap_sgtable(attachment->dev, sg, dir, >>> DMA_ATTR_SKIP_CPU_SYNC); >>> sg_free_table(sg); >>> kfree(sg); >>> >>> diff --git a/drivers/gpu/drm/i915/gem/selftests/mock_dmabuf.c >>> b/drivers/gpu/drm/i915/gem/selftests/mock_dmabuf.c >>> index debaf7b18ab5..be30b27e2926 100644 >>> --- a/drivers/gpu/drm/i915/gem/selftests/mock_dmabuf.c >>> +++ b/drivers/gpu/drm/i915/gem/selftests/mock_dmabuf.c >>> @@ -28,10 +28,9 @@ static struct sg_table *mock_map_dma_buf(struct >>> dma_buf_attachment *attachment, >>> sg = sg_next(sg); >>> } >>> >>> - if (!dma_map_sg(attachment->dev, st->sgl, st->nents, dir)) { >>> - err = -ENOMEM; >>> + err = dma_map_sgtable(attachment->dev, st, dir, 0); >>> + if (err) >>> goto err_st; >>> - } >>> >>> return st; >>> >>> @@ -46,7 +45,7 @@ static void mock_unmap_dma_buf(struct >>> dma_buf_attachment *attachment, >>> struct sg_table *st, >>> enum dma_data_direction dir) >>> { >>> - dma_unmap_sg(attachment->dev, st->sgl, st->nents, dir); >>> + dma_unmap_sgtable(attachment->dev, st, dir, 0); >>> sg_free_table(st); >>> kfree(st); >>> } >>> -- >>> 2.17.1 >>> >>> _______________________________________________ >>> Intel-gfx mailing list >>> Intel-gfx@lists.freedesktop.org >>> https://lists.freedesktop.org/mailman/listinfo/intel-gfx
diff --git a/drivers/gpu/drm/i915/gem/i915_gem_dmabuf.c b/drivers/gpu/drm/i915/gem/i915_gem_dmabuf.c index 2679380159fc..8a988592715b 100644 --- a/drivers/gpu/drm/i915/gem/i915_gem_dmabuf.c +++ b/drivers/gpu/drm/i915/gem/i915_gem_dmabuf.c @@ -48,12 +48,9 @@ static struct sg_table *i915_gem_map_dma_buf(struct dma_buf_attachment *attachme src = sg_next(src); } - if (!dma_map_sg_attrs(attachment->dev, - st->sgl, st->nents, dir, - DMA_ATTR_SKIP_CPU_SYNC)) { - ret = -ENOMEM; + ret = dma_map_sgtable(attachment->dev, st, dir, DMA_ATTR_SKIP_CPU_SYNC); + if (ret) goto err_free_sg; - } return st; @@ -73,9 +70,7 @@ static void i915_gem_unmap_dma_buf(struct dma_buf_attachment *attachment, { struct drm_i915_gem_object *obj = dma_buf_to_obj(attachment->dmabuf); - dma_unmap_sg_attrs(attachment->dev, - sg->sgl, sg->nents, dir, - DMA_ATTR_SKIP_CPU_SYNC); + dma_unmap_sgtable(attachment->dev, sg, dir, DMA_ATTR_SKIP_CPU_SYNC); sg_free_table(sg); kfree(sg); diff --git a/drivers/gpu/drm/i915/gem/selftests/mock_dmabuf.c b/drivers/gpu/drm/i915/gem/selftests/mock_dmabuf.c index debaf7b18ab5..be30b27e2926 100644 --- a/drivers/gpu/drm/i915/gem/selftests/mock_dmabuf.c +++ b/drivers/gpu/drm/i915/gem/selftests/mock_dmabuf.c @@ -28,10 +28,9 @@ static struct sg_table *mock_map_dma_buf(struct dma_buf_attachment *attachment, sg = sg_next(sg); } - if (!dma_map_sg(attachment->dev, st->sgl, st->nents, dir)) { - err = -ENOMEM; + err = dma_map_sgtable(attachment->dev, st, dir, 0); + if (err) goto err_st; - } return st; @@ -46,7 +45,7 @@ static void mock_unmap_dma_buf(struct dma_buf_attachment *attachment, struct sg_table *st, enum dma_data_direction dir) { - dma_unmap_sg(attachment->dev, st->sgl, st->nents, dir); + dma_unmap_sgtable(attachment->dev, st, dir, 0); sg_free_table(st); kfree(st); }
The Documentation/DMA-API-HOWTO.txt states that the dma_map_sg() function returns the number of the created entries in the DMA address space. However the subsequent calls to the dma_sync_sg_for_{device,cpu}() and dma_unmap_sg must be called with the original number of the entries passed to the dma_map_sg(). struct sg_table is a common structure used for describing a non-contiguous memory buffer, used commonly in the DRM and graphics subsystems. It consists of a scatterlist with memory pages and DMA addresses (sgl entry), as well as the number of scatterlist entries: CPU pages (orig_nents entry) and DMA mapped pages (nents entry). It turned out that it was a common mistake to misuse nents and orig_nents entries, calling DMA-mapping functions with a wrong number of entries or ignoring the number of mapped entries returned by the dma_map_sg() function. This driver creatively uses sg_table->orig_nents to store the size of the allocated scatterlist and ignores the number of the entries returned by dma_map_sg function. The sg_table->orig_nents is (mis)used to properly free the (over)allocated scatterlist. This patch only introduces the common DMA-mapping wrappers operating directly on the struct sg_table objects to the dmabuf related functions, so the other drivers, which might share buffers with i915 could rely on the properly set nents and orig_nents values. Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com> --- drivers/gpu/drm/i915/gem/i915_gem_dmabuf.c | 11 +++-------- drivers/gpu/drm/i915/gem/selftests/mock_dmabuf.c | 7 +++---- 2 files changed, 6 insertions(+), 12 deletions(-)