[Intel-gfx] [PATCH] drm/i915: Drop stealing of bits from i915_sw_fence function pointer
Matthew Brost
matthew.brost at intel.com
Wed Sep 22 15:40:50 UTC 2021
On Wed, Sep 22, 2021 at 04:25:04PM +0100, Tvrtko Ursulin wrote:
>
> On 22/09/2021 16:21, Tvrtko Ursulin wrote:
> >
> > On 22/09/2021 15:57, Matthew Brost wrote:
> > > Rather than stealing bits from i915_sw_fence function pointer use
> > > seperate fields for function pointer and flags. If using two different
> > > fields, the 4 byte alignment for the i915_sw_fence function pointer can
> > > also be dropped.
> > >
> > > v2:
> > > (CI)
> > > - Set new function field rather than flags in __i915_sw_fence_init
> > >
> > > Signed-off-by: Matthew Brost <matthew.brost at intel.com>
> > > ---
> > > drivers/gpu/drm/i915/display/intel_display.c | 2 +-
> > > drivers/gpu/drm/i915/gem/i915_gem_context.c | 2 +-
> > > drivers/gpu/drm/i915/i915_request.c | 4 ++--
> > > drivers/gpu/drm/i915/i915_sw_fence.c | 12 +++++------
> > > drivers/gpu/drm/i915/i915_sw_fence.h | 21 +++++++++----------
> > > drivers/gpu/drm/i915/i915_sw_fence_work.c | 2 +-
> > > .../gpu/drm/i915/selftests/i915_sw_fence.c | 2 +-
> > > drivers/gpu/drm/i915/selftests/lib_sw_fence.c | 4 ++--
> > > 8 files changed, 23 insertions(+), 26 deletions(-)
> > >
> > > diff --git a/drivers/gpu/drm/i915/display/intel_display.c
> > > b/drivers/gpu/drm/i915/display/intel_display.c
> > > index a7ca38613f89..6d5bb55ffc82 100644
> > > --- a/drivers/gpu/drm/i915/display/intel_display.c
> > > +++ b/drivers/gpu/drm/i915/display/intel_display.c
> > > @@ -10323,7 +10323,7 @@ static void intel_atomic_commit_work(struct
> > > work_struct *work)
> > > intel_atomic_commit_tail(state);
> > > }
> > > -static int __i915_sw_fence_call
> > > +static int
> > > intel_atomic_commit_ready(struct i915_sw_fence *fence,
> > > enum i915_sw_fence_notify notify)
> > > {
> > > diff --git a/drivers/gpu/drm/i915/gem/i915_gem_context.c
> > > b/drivers/gpu/drm/i915/gem/i915_gem_context.c
> > > index c2ab0e22db0a..df5fec5c3da8 100644
> > > --- a/drivers/gpu/drm/i915/gem/i915_gem_context.c
> > > +++ b/drivers/gpu/drm/i915/gem/i915_gem_context.c
> > > @@ -800,7 +800,7 @@ static void free_engines_rcu(struct rcu_head *rcu)
> > > free_engines(engines);
> > > }
> > > -static int __i915_sw_fence_call
> > > +static int
> > > engines_notify(struct i915_sw_fence *fence, enum
> > > i915_sw_fence_notify state)
> > > {
> > > struct i915_gem_engines *engines =
> > > diff --git a/drivers/gpu/drm/i915/i915_request.c
> > > b/drivers/gpu/drm/i915/i915_request.c
> > > index ce446716d092..945d3025a0b6 100644
> > > --- a/drivers/gpu/drm/i915/i915_request.c
> > > +++ b/drivers/gpu/drm/i915/i915_request.c
> > > @@ -719,7 +719,7 @@ void i915_request_cancel(struct i915_request
> > > *rq, int error)
> > > intel_context_cancel_request(rq->context, rq);
> > > }
> > > -static int __i915_sw_fence_call
> > > +static int
> > > submit_notify(struct i915_sw_fence *fence, enum
> > > i915_sw_fence_notify state)
> > > {
> > > struct i915_request *request =
> > > @@ -755,7 +755,7 @@ submit_notify(struct i915_sw_fence *fence, enum
> > > i915_sw_fence_notify state)
> > > return NOTIFY_DONE;
> > > }
> > > -static int __i915_sw_fence_call
> > > +static int
> > > semaphore_notify(struct i915_sw_fence *fence, enum
> > > i915_sw_fence_notify state)
> > > {
> > > struct i915_request *rq = container_of(fence, typeof(*rq),
> > > semaphore);
> > > diff --git a/drivers/gpu/drm/i915/i915_sw_fence.c
> > > b/drivers/gpu/drm/i915/i915_sw_fence.c
> > > index c589a681da77..1c080dd1f718 100644
> > > --- a/drivers/gpu/drm/i915/i915_sw_fence.c
> > > +++ b/drivers/gpu/drm/i915/i915_sw_fence.c
> > > @@ -34,7 +34,7 @@ enum {
> > > static void *i915_sw_fence_debug_hint(void *addr)
> > > {
> > > - return (void *)(((struct i915_sw_fence *)addr)->flags &
> > > I915_SW_FENCE_MASK);
> > > + return (void *)(((struct i915_sw_fence *)addr)->fn);
> > > }
> > > #ifdef CONFIG_DRM_I915_SW_FENCE_DEBUG_OBJECTS
> > > @@ -126,10 +126,7 @@ static inline void debug_fence_assert(struct
> > > i915_sw_fence *fence)
> > > static int __i915_sw_fence_notify(struct i915_sw_fence *fence,
> > > enum i915_sw_fence_notify state)
> > > {
> > > - i915_sw_fence_notify_t fn;
> > > -
> > > - fn = (i915_sw_fence_notify_t)(fence->flags & I915_SW_FENCE_MASK);
> > > - return fn(fence, state);
> > > + return fence->fn(fence, state);
> > > }
> > > #ifdef CONFIG_DRM_I915_SW_FENCE_DEBUG_OBJECTS
> > > @@ -242,10 +239,11 @@ void __i915_sw_fence_init(struct i915_sw_fence
> > > *fence,
> > > const char *name,
> > > struct lock_class_key *key)
> > > {
> > > - BUG_ON(!fn || (unsigned long)fn & ~I915_SW_FENCE_MASK);
> > > + BUG_ON(!fn);
> > > __init_waitqueue_head(&fence->wait, name, key);
> > > - fence->flags = (unsigned long)fn;
> > > + fence->fn = fn;
> > > + fence->flags = 0;
> > > i915_sw_fence_reinit(fence);
> > > }
> > > diff --git a/drivers/gpu/drm/i915/i915_sw_fence.h
> > > b/drivers/gpu/drm/i915/i915_sw_fence.h
> > > index 30a863353ee6..70ba1789aa89 100644
> > > --- a/drivers/gpu/drm/i915/i915_sw_fence.h
> > > +++ b/drivers/gpu/drm/i915/i915_sw_fence.h
> > > @@ -17,26 +17,25 @@
> > > struct completion;
> > > struct dma_resv;
> > > +struct i915_sw_fence;
> > > +
> > > +enum i915_sw_fence_notify {
> > > + FENCE_COMPLETE,
> > > + FENCE_FREE
> > > +};
> > > +
> > > +typedef int (*i915_sw_fence_notify_t)(struct i915_sw_fence *,
> > > + enum i915_sw_fence_notify state);
> > > struct i915_sw_fence {
> > > wait_queue_head_t wait;
> > > + i915_sw_fence_notify_t fn;
> > > unsigned long flags;
> >
> > Looks good to me. I'd just make the flags narrower now that they can be,
> > and put them down..
> >
> > > atomic_t pending;
> >
> > .. here as unsigned int and so we save 4 bytes, maybe.
>
> No this won't work due test_and_set_bit needs a long, oh well.
>
> >
> > In fact, unless CONFIG_DRM_I915_SW_FENCE_CHECK_DAG is on, which it won't
> > be on release builds, I don't think anything uses flags any more. So you
> > could even omit the flags in that case. Might be cumbersome so can leave
> > for later, but would sure be nice not to waste space if we can avoid it.
> >
> > Also please double check if i915_sw_fence_reinit() will be fine and
> > won't bug on since fence->flags is always zero now I think.
>
Yes, the BUG_ON(!fence->flags) is going to blow up, good catch. Will
skip this revisions testing and repost with this fixed.
If we add a few 'ifdef CONFIG_DRM_I915_SW_FENCE_CHECK_DAG' we indeed can
only include fence->flags if CONFIG_DRM_I915_SW_FENCE_CHECK_DAG is
defined. Will include in next rev.
Matt
> But these two are worth checking out.
>
> Regards,
>
> Tvrtko
>
> >
> > Regards,
> >
> > Tvrtko
> >
> > > int error;
> > > };
> > > #define I915_SW_FENCE_CHECKED_BIT 0 /* used internally for DAG
> > > checking */
> > > -#define I915_SW_FENCE_PRIVATE_BIT 1 /* available for use by owner */
> > > -#define I915_SW_FENCE_MASK (~3)
> > > -
> > > -enum i915_sw_fence_notify {
> > > - FENCE_COMPLETE,
> > > - FENCE_FREE
> > > -};
> > > -
> > > -typedef int (*i915_sw_fence_notify_t)(struct i915_sw_fence *,
> > > - enum i915_sw_fence_notify state);
> > > -#define __i915_sw_fence_call __aligned(4)
> > > void __i915_sw_fence_init(struct i915_sw_fence *fence,
> > > i915_sw_fence_notify_t fn,
> > > diff --git a/drivers/gpu/drm/i915/i915_sw_fence_work.c
> > > b/drivers/gpu/drm/i915/i915_sw_fence_work.c
> > > index 5b33ef23d54c..d2e56b387993 100644
> > > --- a/drivers/gpu/drm/i915/i915_sw_fence_work.c
> > > +++ b/drivers/gpu/drm/i915/i915_sw_fence_work.c
> > > @@ -23,7 +23,7 @@ static void fence_work(struct work_struct *work)
> > > dma_fence_put(&f->dma);
> > > }
> > > -static int __i915_sw_fence_call
> > > +static int
> > > fence_notify(struct i915_sw_fence *fence, enum
> > > i915_sw_fence_notify state)
> > > {
> > > struct dma_fence_work *f = container_of(fence, typeof(*f), chain);
> > > diff --git a/drivers/gpu/drm/i915/selftests/i915_sw_fence.c
> > > b/drivers/gpu/drm/i915/selftests/i915_sw_fence.c
> > > index cbf45d85cbff..daa985e5a19b 100644
> > > --- a/drivers/gpu/drm/i915/selftests/i915_sw_fence.c
> > > +++ b/drivers/gpu/drm/i915/selftests/i915_sw_fence.c
> > > @@ -28,7 +28,7 @@
> > > #include "../i915_selftest.h"
> > > -static int __i915_sw_fence_call
> > > +static int
> > > fence_notify(struct i915_sw_fence *fence, enum
> > > i915_sw_fence_notify state)
> > > {
> > > switch (state) {
> > > diff --git a/drivers/gpu/drm/i915/selftests/lib_sw_fence.c
> > > b/drivers/gpu/drm/i915/selftests/lib_sw_fence.c
> > > index 080b90b63d16..eb59a41bdb79 100644
> > > --- a/drivers/gpu/drm/i915/selftests/lib_sw_fence.c
> > > +++ b/drivers/gpu/drm/i915/selftests/lib_sw_fence.c
> > > @@ -26,7 +26,7 @@
> > > /* Small library of different fence types useful for writing tests */
> > > -static int __i915_sw_fence_call
> > > +static int
> > > nop_fence_notify(struct i915_sw_fence *fence, enum
> > > i915_sw_fence_notify state)
> > > {
> > > return NOTIFY_DONE;
> > > @@ -89,7 +89,7 @@ struct heap_fence {
> > > };
> > > };
> > > -static int __i915_sw_fence_call
> > > +static int
> > > heap_fence_notify(struct i915_sw_fence *fence, enum
> > > i915_sw_fence_notify state)
> > > {
> > > struct heap_fence *h = container_of(fence, typeof(*h), fence);
> > >
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