Re: [PATCH 03/17] drm/i915: Pin pages whilst mapping the dma-buf

Daniel Vetter
2013-09-02T06:03:55Z

On Fri, Aug 30, 2013 at 03:27:47PM +0100, Damien Lespiau wrote:
> On Mon, Aug 26, 2013 at 07:50:55PM -0300, Rodrigo Vivi wrote:
> > From: Chris Wilson <chris@chris-wilson.co.uk>
> >
> > As we attempt to kmalloc after calling get_pages, there is a possibility
> > that the shrinker may reap the pages we just acquired. To prevent this
> > we need to increment the pages_pin_count early, so rearrange the code
> > and error paths to make it so.
> >
> > Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
>
> Reviewed-by: Damien Lespiau <damien.lespiau@intel.com>

I've merged the three reviewed patches to dinq, thanks.
-Daniel
>
> --
> Damien
>
> > ---
> > drivers/gpu/drm/i915/i915_gem_dmabuf.c | 41 ++++++++++++++++++----------------
> > 1 file changed, 22 insertions(+), 19 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/i915/i915_gem_dmabuf.c b/drivers/gpu/drm/i915/i915_gem_dmabuf.c
> > index e918b05..7d5752f 100644
> > --- a/drivers/gpu/drm/i915/i915_gem_dmabuf.c
> > +++ b/drivers/gpu/drm/i915/i915_gem_dmabuf.c
> > @@ -42,27 +42,24 @@ static struct sg_table *i915_gem_map_dma_buf(struct dma_buf_attachment *attachme
> >
> > ret = i915_mutex_lock_interruptible(obj->base.dev);
> > if (ret)
> > - return ERR_PTR(ret);
> > + goto err;
> >
> > ret = i915_gem_object_get_pages(obj);
> > - if (ret) {
> > - st = ERR_PTR(ret);
> > - goto out;
> > - }
> > + if (ret)
> > + goto err_unlock;
> > +
> > + i915_gem_object_pin_pages(obj);
> >
> > /* Copy sg so that we make an independent mapping */
> > st = kmalloc(sizeof(struct sg_table), GFP_KERNEL);
> > if (st == NULL) {
> > - st = ERR_PTR(-ENOMEM);
> > - goto out;
> > + ret = -ENOMEM;
> > + goto err_unpin;
> > }
> >
> > ret = sg_alloc_table(st, obj->pages->nents, GFP_KERNEL);
> > - if (ret) {
> > - kfree(st);
> > - st = ERR_PTR(ret);
> > - goto out;
> > - }
> > + if (ret)
> > + goto err_free;
> >
> > src = obj->pages->sgl;
> > dst = st->sgl;
> > @@ -73,17 +70,23 @@ static struct sg_table *i915_gem_map_dma_buf(struct dma_buf_attachment *attachme
> > }
> >
> > if (!dma_map_sg(attachment->dev, st->sgl, st->nents, dir)) {
> > - sg_free_table(st);
> > - kfree(st);
> > - st = ERR_PTR(-ENOMEM);
> > - goto out;
> > + ret =-ENOMEM;
> > + goto err_free_sg;
> > }
> >
> > - i915_gem_object_pin_pages(obj);
> > -
> > -out:
> > mutex_unlock(&obj->base.dev->struct_mutex);
> > return st;
> > +
> > +err_free_sg:
> > + sg_free_table(st);
> > +err_free:
> > + kfree(st);
> > +err_unpin:
> > + i915_gem_object_unpin_pages(obj);
> > +err_unlock:
> > + mutex_unlock(&obj->base.dev->struct_mutex);
> > +err:
> > + return ERR_PTR(ret);
> > }
> >
> > static void i915_gem_unmap_dma_buf(struct dma_buf_attachment *attachment,
> > --
> > 1.8.1.4
> >
> > _______________________________________________
> > Intel-gfx mailing list
> > Intel-gfx@lists.freedesktop.org
> > http://lists.freedesktop.org/mailman/listinfo/intel-gfx
> _______________________________________________
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> http://lists.freedesktop.org/mailman/listinfo/intel-gfx

--
Daniel Vetter
Software Engineer, Intel Corporation
+41 (0) 79 365 57 48 - http://blog.ffwll.ch