| Message ID | 1404238671-18760-13-git-send-email-benjamin.widawsky@intel.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Tue, Jul 01, 2014 at 11:17:47AM -0700, Ben Widawsky wrote: > The comment [which was mine] is wrong. The context object can never be > bound in a PPGTT because it is only capable of living in the Global GTT. > So, remove the comment, and reorder the unref. What's nice about the > latter is it keeps the context object alive past the PPGTT. This makes > the destroy ordering symmetric with the creation ordering. > > Create: > 1. Create context > 2. Create PPGTT > > Destroy: > 1. Destroy PPGTT > 2. Destroy context > > As far as I know, this does not fix a bug. The code previously kept the > context data structure, only the object was gone. As the code was, > nothing tried to use the object after this point. > > NOTE: If in the future we have cases where the PPGTT can/should outlive > the context (which doesn't occur today, but the code permits it), this > ordering does not matter. Even if this occurs, as it stands now, we do > not expect that to be the normal case, and having this order makes > debugging a bit easier if we're tracking object lifetimes for the > context vs ppgtt > > Signed-off-by: Ben Widawsky <ben@bwidawsk.net> Queued for -next, thanks for the patch. -Daniel > --- > drivers/gpu/drm/i915/i915_gem_context.c | 6 ++---- > 1 file changed, 2 insertions(+), 4 deletions(-) > > diff --git a/drivers/gpu/drm/i915/i915_gem_context.c b/drivers/gpu/drm/i915/i915_gem_context.c > index b6803b3..8d106d9 100644 > --- a/drivers/gpu/drm/i915/i915_gem_context.c > +++ b/drivers/gpu/drm/i915/i915_gem_context.c > @@ -185,14 +185,12 @@ void i915_gem_context_free(struct kref *ctx_ref) > /* We refcount even the aliasing PPGTT to keep the code symmetric */ > if (USES_PPGTT(ctx->obj->base.dev)) > ppgtt = ctx_to_ppgtt(ctx); > - > - /* XXX: Free up the object before tearing down the address space, in > - * case we're bound in the PPGTT */ > - drm_gem_object_unreference(&ctx->obj->base); > } > > if (ppgtt) > kref_put(&ppgtt->ref, ppgtt_release); > + if (ctx->obj) > + drm_gem_object_unreference(&ctx->obj->base); > list_del(&ctx->link); > kfree(ctx); > } > -- > 2.0.1 > > _______________________________________________ > Intel-gfx mailing list > Intel-gfx@lists.freedesktop.org > http://lists.freedesktop.org/mailman/listinfo/intel-gfx
diff --git a/drivers/gpu/drm/i915/i915_gem_context.c b/drivers/gpu/drm/i915/i915_gem_context.c index b6803b3..8d106d9 100644 --- a/drivers/gpu/drm/i915/i915_gem_context.c +++ b/drivers/gpu/drm/i915/i915_gem_context.c @@ -185,14 +185,12 @@ void i915_gem_context_free(struct kref *ctx_ref) /* We refcount even the aliasing PPGTT to keep the code symmetric */ if (USES_PPGTT(ctx->obj->base.dev)) ppgtt = ctx_to_ppgtt(ctx); - - /* XXX: Free up the object before tearing down the address space, in - * case we're bound in the PPGTT */ - drm_gem_object_unreference(&ctx->obj->base); } if (ppgtt) kref_put(&ppgtt->ref, ppgtt_release); + if (ctx->obj) + drm_gem_object_unreference(&ctx->obj->base); list_del(&ctx->link); kfree(ctx); }
The comment [which was mine] is wrong. The context object can never be bound in a PPGTT because it is only capable of living in the Global GTT. So, remove the comment, and reorder the unref. What's nice about the latter is it keeps the context object alive past the PPGTT. This makes the destroy ordering symmetric with the creation ordering. Create: 1. Create context 2. Create PPGTT Destroy: 1. Destroy PPGTT 2. Destroy context As far as I know, this does not fix a bug. The code previously kept the context data structure, only the object was gone. As the code was, nothing tried to use the object after this point. NOTE: If in the future we have cases where the PPGTT can/should outlive the context (which doesn't occur today, but the code permits it), this ordering does not matter. Even if this occurs, as it stands now, we do not expect that to be the normal case, and having this order makes debugging a bit easier if we're tracking object lifetimes for the context vs ppgtt Signed-off-by: Ben Widawsky <ben@bwidawsk.net> --- drivers/gpu/drm/i915/i915_gem_context.c | 6 ++---- 1 file changed, 2 insertions(+), 4 deletions(-)