Hi all,
Jason wanted to do that as part of the scheduler series, but I object since rcu is very, very hard to review when adding, and much, much harder even to review when removing.
This is because simply looking for __rcu pointer annotations and rcu functions isn't enough, rcu is also relied upon in many datastructures which have internally and rcu_read_lock protection (or at least the required amount of barriers), like xarray.
The other problem is that it inherits when chasing pointers, e.g. i915_gem_engines has an rcu pointer to intel_context, which has a non-rcu pointer to i915_address_space. But since we could look-up the entire chain under rcu i.e. engines->context[i]->vm this means more code to audit.
The audit explodes pretty quickly.
Anyway I'm reasonable confident I got them all in the current code, and slightly less confident that I managed to stitch together the full history.
References to relevant commits throughout the series.
Cheers, Daniel
Daniel Vetter (9): drm/i915: Drop code to handle set-vm races from execbuf drm/i915: Rename i915_gem_context_get_vm_rcu to i915_gem_context_get_eb_vm drm/i915: Use i915_gem_context_get_eb_vm in ctx_getparam drm/i915: Add i915_gem_context_is_full_ppgtt drm/i915: Use i915_gem_context_get_eb_vm in intel_context_set_gem drm/i915: Drop __rcu from gem_context->vm drm/i915: use xa_lock/unlock for fpriv->vm_xa lookups drm/i915: Stop rcu support for i915_address_space drm/i915: Split out intel_context_create_user
drivers/gpu/drm/i915/gem/i915_gem_context.c | 82 ++++--------------- drivers/gpu/drm/i915/gem/i915_gem_context.h | 13 ++- .../gpu/drm/i915/gem/i915_gem_context_types.h | 2 +- .../gpu/drm/i915/gem/i915_gem_execbuffer.c | 12 ++- .../gpu/drm/i915/gem/selftests/huge_pages.c | 8 +- .../drm/i915/gem/selftests/i915_gem_context.c | 32 +++----- .../gpu/drm/i915/gem/selftests/mock_context.c | 2 +- drivers/gpu/drm/i915/gt/intel_context.c | 22 ++++- drivers/gpu/drm/i915/gt/intel_context.h | 2 + drivers/gpu/drm/i915/gt/intel_ggtt.c | 1 - drivers/gpu/drm/i915/gt/intel_gtt.c | 6 +- drivers/gpu/drm/i915/gt/intel_gtt.h | 2 +- drivers/gpu/drm/i915/gt/selftest_execlists.c | 2 +- drivers/gpu/drm/i915/gt/selftest_hangcheck.c | 2 +- drivers/gpu/drm/i915/i915_drv.h | 4 +- drivers/gpu/drm/i915/i915_trace.h | 2 +- drivers/gpu/drm/i915/selftests/i915_gem_gtt.c | 4 +- drivers/gpu/drm/i915/selftests/i915_vma.c | 4 +- 18 files changed, 79 insertions(+), 123 deletions(-)