Hi, Michael, thanks for looking at this.
On 6/25/21 6:02 PM, Ruhl, Michael J wrote:
-----Original Message----- From: dri-devel <dri-devel-boun...@lists.freedesktop.org> On Behalf Of Thomas Hellström Sent: Thursday, June 24, 2021 2:31 PM To: intel-...@lists.freedesktop.org; dri-devel@lists.freedesktop.org Cc: Thomas Hellström <thomas.hellst...@linux.intel.com>; Auld, Matthew <matthew.a...@intel.com> Subject: [PATCH 4/4] drm/i915/gem: Migrate to system at dma-buf map time Until we support p2p dma or as a complement to that, migrate data to system memory at dma-buf map time if possible. Signed-off-by: Thomas Hellström <thomas.hellst...@linux.intel.com> --- drivers/gpu/drm/i915/gem/i915_gem_dmabuf.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-) diff --git a/drivers/gpu/drm/i915/gem/i915_gem_dmabuf.c b/drivers/gpu/drm/i915/gem/i915_gem_dmabuf.c index 616c3a2f1baf..a52f885bc09a 100644 --- a/drivers/gpu/drm/i915/gem/i915_gem_dmabuf.c +++ b/drivers/gpu/drm/i915/gem/i915_gem_dmabuf.c @@ -25,7 +25,14 @@ static struct sg_table *i915_gem_map_dma_buf(struct dma_buf_attachment *attachme struct scatterlist *src, *dst; int ret, i; - ret = i915_gem_object_pin_pages_unlocked(obj); + ret = i915_gem_object_lock_interruptible(obj, NULL);Hmm, I believe in most cases that the caller should be holding the lock (object dma-resv) on this object already.
Yes, I agree, In particular for other instances of our own driver, at least since the dma_resv introduction.
But I also think that's a pre-existing bug, since i915_gem_object_pin_pages_unlocked() will also take the lock.
I Think we need to initially make the exporter dynamic-capable to resolve this, and drop the locking here completely, as dma-buf docs says that we're then guaranteed to get called with the object lock held.
I figure if we make the exporter dynamic, we need to migrate already at dma_buf_pin time so we don't pin the object in the wrong location.
/Thomas
I know for the dynamic version of dma-buf, there is a check to make sure that the lock is held when called. I think you will run into some issues if you try to get it here as well. Mike+ if (ret) + return ERR_PTR(ret); + + ret = i915_gem_object_migrate(obj, NULL, INTEL_REGION_SMEM); + if (!ret) + ret = i915_gem_object_pin_pages(obj); + i915_gem_object_unlock(obj); if (ret) goto err; -- 2.31.1
