Am 24.08.22 um 17:03 schrieb Dmitry Osipenko:
On 8/24/22 17:08, Christian König wrote:
Am 24.08.22 um 12:22 schrieb Dmitry Osipenko:
Move dma-buf attachment API functions to the dynamic locking
specification.
The strict locking convention prevents deadlock situations for dma-buf
importers and exporters.
Previously, the "unlocked" versions of the attachment API functions
weren't taking the reservation lock and this patch makes them to take
the lock.
Didn't we concluded that we need to keep the attach and detach callbacks
without the lock and only move the map/unmap callbacks over?
Otherwise it won't be possible for drivers to lock multiple buffers if
they have to shuffle things around for a specific attachment.
We did conclude that. The attach/detach dma-buf ops are unlocked, but
the map_dma_buf/unmap_dma_buf must be invoked under lock and
dma_buf_dynamic_attach_unlocked() maps dma-buf if either importer or
exporter can't handle the dynamic mapping [1].
Ah! You are confusing me over and over again with that :)
Ok in this case that here is fine, I just need to re-read the patch.
Thanks,
Christian.
[1]
https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Felixir.bootlin.com%2Flinux%2Fv6.0-rc2%2Fsource%2Fdrivers%2Fdma-buf%2Fdma-buf.c%23L869&data=05%7C01%7Cchristian.koenig%40amd.com%7Cdf23d89db8b84bf6d4c008da85e1dc6c%7C3dd8961fe4884e608e11a82d994e183d%7C0%7C0%7C637969502441026991%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C&sdata=d8kWKjDCFn%2B3KmK135Gcv6%2FMLffEYcipouqWxfc%2BKXM%3D&reserved=0
Hence I re-arranged the dma_resv_lock() in
dma_buf_dynamic_attach_unlocked() to move both pinning and mapping under
the held lock.
