| Message ID | 20210902142057.929669-2-daniel.vetter@ffwll.ch (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [01/11] drm/i915: Release i915_gem_context from a worker | expand |
diff --git a/drivers/gpu/drm/i915/gem/i915_gem_context.c b/drivers/gpu/drm/i915/gem/i915_gem_context.c index 051bc357ff65..5a053cf14948 100644 --- a/drivers/gpu/drm/i915/gem/i915_gem_context.c +++ b/drivers/gpu/drm/i915/gem/i915_gem_context.c @@ -994,6 +994,9 @@ static void i915_gem_context_release_work(struct work_struct *work) trace_i915_context_free(ctx); GEM_BUG_ON(!i915_gem_context_is_closed(ctx)); + if (ctx->syncobj) + drm_syncobj_put(ctx->syncobj); + mutex_destroy(&ctx->engines_mutex); mutex_destroy(&ctx->lut_mutex); @@ -1220,9 +1223,6 @@ static void context_close(struct i915_gem_context *ctx) if (vm) i915_vm_close(vm); - if (ctx->syncobj) - drm_syncobj_put(ctx->syncobj); - ctx->file_priv = ERR_PTR(-EBADF); /*
gem context refcounting is another exercise in least locking design it seems, where most things get destroyed upon context closure (which can race with anything really). Only the actual memory allocation and the locks survive while holding a reference. This tripped up Jason when reimplementing the single timeline feature in commit 00dae4d3d35d4f526929633b76e00b0ab4d3970d Author: Jason Ekstrand <jason@jlekstrand.net> Date: Thu Jul 8 10:48:12 2021 -0500 drm/i915: Implement SINGLE_TIMELINE with a syncobj (v4) We could fix the bug by holding ctx->mutex in execbuf and clear the pointer (again while holding the mutex) context_close, but it's cleaner to just make the context object actually invariant over its _entire_ lifetime. This way any other ioctl that's potentially racing, but holding a full reference, can still rely on ctx->syncobj being an immutable pointer. Which without this change, is not the case. Reviewed-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com> Signed-off-by: Daniel Vetter <daniel.vetter@intel.com> Fixes: 00dae4d3d35d ("drm/i915: Implement SINGLE_TIMELINE with a syncobj (v4)") Cc: Jason Ekstrand <jason@jlekstrand.net> Cc: Chris Wilson <chris@chris-wilson.co.uk> Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com> Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com> Cc: Matthew Brost <matthew.brost@intel.com> Cc: Matthew Auld <matthew.auld@intel.com> Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com> Cc: "Thomas Hellström" <thomas.hellstrom@intel.com> Cc: Lionel Landwerlin <lionel.g.landwerlin@intel.com> Cc: Dave Airlie <airlied@redhat.com> --- drivers/gpu/drm/i915/gem/i915_gem_context.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-)