Am 18.06.2018 um 10:22 schrieb Daniel Vetter:
> On Fri, Jun 01, 2018 at 02:00:18PM +0200, Christian König wrote:
>> First step towards unpinned DMA buf operation.
>>
>> I've checked the DRM drivers to potential locking of the reservation
>> object, but essentially we need to audit all implementations of the
>> dma_buf _ops for this to work.
>>
>> Signed-off-by: Christian König <christian.koenig at amd.com>
> Agreed in principle, but I expect a fireworks show with just this patch
> applied. It's not just that we need to audit all the implementations of
> dma-buf-ops, we also need to audit all the callers.
Ah, yeah of course a good point.
> No idea yet how to go about merging this, but for a start might be good to
> throw this at the intel-gfx CI (just Cc: the intel-gfx mailing lists, but
> make sure your series applies without amd-staging-next stuff which isn't
> in drm.git yet).
Ok, going to incorporate all your other comments as well and then send
the next round of this with CCing intel-gfx as well.
Thanks for the review,
Christian.
> -Daniel
>
>> ---
>> drivers/dma-buf/dma-buf.c | 4 ++++
>> include/linux/dma-buf.h | 4 ++++
>> 2 files changed, 8 insertions(+)
>>
>> diff --git a/drivers/dma-buf/dma-buf.c b/drivers/dma-buf/dma-buf.c
>> index e4c657d9fad7..4f0708cb58a7 100644
>> --- a/drivers/dma-buf/dma-buf.c
>> +++ b/drivers/dma-buf/dma-buf.c
>> @@ -631,7 +631,9 @@ struct sg_table *dma_buf_map_attachment(struct dma_buf_attachment *attach,
>> if (WARN_ON(!attach || !attach->dmabuf))
>> return ERR_PTR(-EINVAL);
>>
>> + reservation_object_lock(attach->dmabuf->resv, NULL);
>> sg_table = attach->dmabuf->ops->map_dma_buf(attach, direction);
>> + reservation_object_unlock(attach->dmabuf->resv);
>> if (!sg_table)
>> sg_table = ERR_PTR(-ENOMEM);
>>
>> @@ -658,8 +660,10 @@ void dma_buf_unmap_attachment(struct dma_buf_attachment *attach,
>> if (WARN_ON(!attach || !attach->dmabuf || !sg_table))
>> return;
>>
>> + reservation_object_lock(attach->dmabuf->resv, NULL);
>> attach->dmabuf->ops->unmap_dma_buf(attach, sg_table,
>> direction);
>> + reservation_object_unlock(attach->dmabuf->resv);
>> }
>> EXPORT_SYMBOL_GPL(dma_buf_unmap_attachment);
>>
>> diff --git a/include/linux/dma-buf.h b/include/linux/dma-buf.h
>> index d17cadd76802..d2ba7a027a78 100644
>> --- a/include/linux/dma-buf.h
>> +++ b/include/linux/dma-buf.h
>> @@ -118,6 +118,8 @@ struct dma_buf_ops {
>> * any other kind of sharing that the exporter might wish to make
>> * available to buffer-users.
>> *
>> + * This is called with the dmabuf->resv object locked.
>> + *
>> * Returns:
>> *
>> * A &sg_table scatter list of or the backing storage of the DMA buffer,
>> @@ -138,6 +140,8 @@ struct dma_buf_ops {
>> * It should also unpin the backing storage if this is the last mapping
>> * of the DMA buffer, it the exporter supports backing storage
>> * migration.
>> + *
>> + * This is called with the dmabuf->resv object locked.
>> */
>> void (*unmap_dma_buf)(struct dma_buf_attachment *,
>> struct sg_table *,
>> --
>> 2.14.1
>>
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