intel: Use atomic refcounters

As the target architecture for Intel GPUs is the x86, we can presume to
have reasonable compiler support for Intel atomic intrinsics, i.e. gcc,
and so use those in preference to pulling in a complicated mess of
fragile assembly.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
[anholt: hand-resolved against my previous commit.  This brings cairo-gl
firefox-talos-gfx time from 65 seconds back down to 62 seconds.]
Signed-off-by: Eric Anholt <eric@anholt.net>

1 files changed, 64 insertions, 64 deletions

diff --git a/libdrm/intel/intel_bufmgr_gem.c b/libdrm/intel/intel_bufmgr_gem.c
index 902c1ed7..ce3cbabd 100644
--- a/libdrm/intel/intel_bufmgr_gem.c
+++ b/libdrm/intel/intel_bufmgr_gem.c
@@ -53,6 +53,7 @@
 
 #include "errno.h"
 #include "libdrm_lists.h"
+#include "intel_atomic.h"
 #include "intel_bufmgr.h"
 #include "intel_bufmgr_priv.h"
 #include "intel_chipset.h"
@@ -102,7 +103,7 @@ typedef struct _drm_intel_bufmgr_gem {
 struct _drm_intel_bo_gem {
     drm_intel_bo bo;
 
-    int refcount;
+    atomic_t refcount;
     /** Boolean whether the mmap ioctl has been called for this buffer yet. */
     uint32_t gem_handle;
     const char *name;
@@ -172,8 +173,6 @@ struct _drm_intel_bo_gem {
     int reloc_tree_fences;
 };
 
-static void drm_intel_gem_bo_reference_locked(drm_intel_bo *bo);
-
 static unsigned int
 drm_intel_gem_estimate_batch_space(drm_intel_bo **bo_array, int count);
 
@@ -189,6 +188,9 @@ drm_intel_gem_bo_set_tiling(drm_intel_bo *bo, uint32_t *tiling_mode,
 			    uint32_t stride);
 
 static void
+drm_intel_gem_bo_unreference_locked(drm_intel_bo *bo);
+
+static void
 drm_intel_gem_bo_unreference(drm_intel_bo *bo);
 
 static void
@@ -237,6 +239,15 @@ static void drm_intel_gem_dump_validation_list(drm_intel_bufmgr_gem *bufmgr_gem)
     }
 }
 
+static void
+drm_intel_gem_bo_reference(drm_intel_bo *bo)
+{
+    drm_intel_bo_gem *bo_gem = (drm_intel_bo_gem *)bo;
+
+    assert(atomic_read(&bo_gem->refcount) > 0);
+    atomic_inc(&bo_gem->refcount);
+}
+
 /**
  * Adds the given buffer to the list of buffers to be validated (moved into the
  * appropriate memory type) with the next batch submission.
@@ -280,7 +291,7 @@ drm_intel_add_validate_buffer(drm_intel_bo *bo)
     bufmgr_gem->exec_objects[index].alignment = 0;
     bufmgr_gem->exec_objects[index].offset = 0;
     bufmgr_gem->exec_bos[index] = bo;
-    drm_intel_gem_bo_reference_locked(bo);
+    drm_intel_gem_bo_reference(bo);
     bufmgr_gem->exec_count++;
 }
 
@@ -436,7 +447,7 @@ retry:
     }
 
     bo_gem->name = name;
-    bo_gem->refcount = 1;
+    atomic_set(&bo_gem->refcount, 1);
     bo_gem->validate_index = -1;
     bo_gem->reloc_tree_size = bo_gem->bo.size;
     bo_gem->reloc_tree_fences = 0;
@@ -499,7 +510,7 @@ drm_intel_bo_gem_create_from_name(drm_intel_bufmgr *bufmgr, const char *name,
     bo_gem->bo.virtual = NULL;
     bo_gem->bo.bufmgr = bufmgr;
     bo_gem->name = name;
-    bo_gem->refcount = 1;
+    atomic_set (&bo_gem->refcount, 1);
     bo_gem->validate_index = -1;
     bo_gem->gem_handle = open_arg.handle;
     bo_gem->global_name = handle;
@@ -525,27 +536,6 @@ drm_intel_bo_gem_create_from_name(drm_intel_bufmgr *bufmgr, const char *name,
 }
 
 static void
-drm_intel_gem_bo_reference(drm_intel_bo *bo)
-{
-    drm_intel_bufmgr_gem *bufmgr_gem = (drm_intel_bufmgr_gem *)bo->bufmgr;
-    drm_intel_bo_gem *bo_gem = (drm_intel_bo_gem *)bo;
-
-    assert(bo_gem->refcount > 0);
-    pthread_mutex_lock(&bufmgr_gem->lock);
-    bo_gem->refcount++;
-    pthread_mutex_unlock(&bufmgr_gem->lock);
-}
-
-static void
-drm_intel_gem_bo_reference_locked(drm_intel_bo *bo)
-{
-    drm_intel_bo_gem *bo_gem = (drm_intel_bo_gem *)bo;
-
-    assert(bo_gem->refcount > 0);
-    bo_gem->refcount++;
-}
-
-static void
 drm_intel_gem_bo_free(drm_intel_bo *bo)
 {
     drm_intel_bufmgr_gem *bufmgr_gem = (drm_intel_bufmgr_gem *)bo->bufmgr;
@@ -597,60 +587,70 @@ drm_intel_gem_cleanup_bo_cache(drm_intel_bufmgr_gem *bufmgr_gem, time_t time)
 }
 
 static void
-drm_intel_gem_bo_unreference_locked(drm_intel_bo *bo)
+drm_intel_gem_bo_unreference_final(drm_intel_bo *bo)
 {
     drm_intel_bufmgr_gem *bufmgr_gem = (drm_intel_bufmgr_gem *)bo->bufmgr;
     drm_intel_bo_gem *bo_gem = (drm_intel_bo_gem *)bo;
+    struct drm_intel_gem_bo_bucket *bucket;
+    uint32_t tiling_mode;
 
-    assert(bo_gem->refcount > 0);
-    if (--bo_gem->refcount == 0) {
-	struct drm_intel_gem_bo_bucket *bucket;
-	uint32_t tiling_mode;
-
-	if (bo_gem->relocs != NULL) {
-	    int i;
+    if (bo_gem->relocs != NULL) {
+	int i;
 
-	    /* Unreference all the target buffers */
-	    for (i = 0; i < bo_gem->reloc_count; i++)
-		 drm_intel_gem_bo_unreference_locked(bo_gem->reloc_target_bo[i]);
-	}
+	/* Unreference all the target buffers */
+	for (i = 0; i < bo_gem->reloc_count; i++)
+	    drm_intel_gem_bo_unreference_locked(bo_gem->reloc_target_bo[i]);
+    }
 
-	DBG("bo_unreference final: %d (%s)\n",
-	    bo_gem->gem_handle, bo_gem->name);
+    DBG("bo_unreference final: %d (%s)\n",
+	bo_gem->gem_handle, bo_gem->name);
 
-	bucket = drm_intel_gem_bo_bucket_for_size(bufmgr_gem, bo->size);
-	/* Put the buffer into our internal cache for reuse if we can. */
-	tiling_mode = I915_TILING_NONE;
-	if (bufmgr_gem->bo_reuse && bo_gem->reusable && bucket != NULL &&
-	    drm_intel_gem_bo_set_tiling(bo, &tiling_mode, 0) == 0)
-	{
-	    struct timespec time;
+    bucket = drm_intel_gem_bo_bucket_for_size(bufmgr_gem, bo->size);
+    /* Put the buffer into our internal cache for reuse if we can. */
+    tiling_mode = I915_TILING_NONE;
+    if (bufmgr_gem->bo_reuse && bo_gem->reusable && bucket != NULL &&
+	drm_intel_gem_bo_set_tiling(bo, &tiling_mode, 0) == 0)
+    {
+	struct timespec time;
 
-	    clock_gettime(CLOCK_MONOTONIC, &time);
-	    bo_gem->free_time = time.tv_sec;
+	clock_gettime(CLOCK_MONOTONIC, &time);
+	bo_gem->free_time = time.tv_sec;
 
-	    bo_gem->name = NULL;
-	    bo_gem->validate_index = -1;
-	    bo_gem->reloc_count = 0;
+	bo_gem->name = NULL;
+	bo_gem->validate_index = -1;
+	bo_gem->reloc_count = 0;
 
-	    DRMLISTADDTAIL(&bo_gem->head, &bucket->head);
+	DRMLISTADDTAIL(&bo_gem->head, &bucket->head);
 
-	    drm_intel_gem_bo_madvise(bufmgr_gem, bo_gem, I915_MADV_DONTNEED);
-	    drm_intel_gem_cleanup_bo_cache(bufmgr_gem, time.tv_sec);
-	} else {
-	    drm_intel_gem_bo_free(bo);
-	}
+	drm_intel_gem_bo_madvise(bufmgr_gem, bo_gem, I915_MADV_DONTNEED);
+	drm_intel_gem_cleanup_bo_cache(bufmgr_gem, time.tv_sec);
+    } else {
+	drm_intel_gem_bo_free(bo);
     }
 }
 
 static void
+drm_intel_gem_bo_unreference_locked(drm_intel_bo *bo)
+{
+    drm_intel_bo_gem *bo_gem = (drm_intel_bo_gem *)bo;
+
+    assert(atomic_read(&bo_gem->refcount) > 0);
+    if (atomic_dec_and_test (&bo_gem->refcount))
+	drm_intel_gem_bo_unreference_final(bo);
+}
+
+static void
 drm_intel_gem_bo_unreference(drm_intel_bo *bo)
 {
-    drm_intel_bufmgr_gem *bufmgr_gem = (drm_intel_bufmgr_gem *)bo->bufmgr;
+    drm_intel_bo_gem *bo_gem = (drm_intel_bo_gem *)bo;
 
-    pthread_mutex_lock(&bufmgr_gem->lock);
-    drm_intel_gem_bo_unreference_locked(bo);
-    pthread_mutex_unlock(&bufmgr_gem->lock);
+    assert(atomic_read(&bo_gem->refcount) > 0);
+    if (atomic_dec_and_test (&bo_gem->refcount)) {
+	drm_intel_bufmgr_gem *bufmgr_gem = (drm_intel_bufmgr_gem *)bo->bufmgr;
+	pthread_mutex_lock(&bufmgr_gem->lock);
+	drm_intel_gem_bo_unreference_final(bo);
+	pthread_mutex_unlock(&bufmgr_gem->lock);
+    }
 }
 
 static int
@@ -1017,7 +1017,7 @@ drm_intel_gem_bo_emit_reloc(drm_intel_bo *bo, uint32_t offset,
     bo_gem->relocs[bo_gem->reloc_count].presumed_offset = target_bo->offset;
 
     bo_gem->reloc_target_bo[bo_gem->reloc_count] = target_bo;
-    drm_intel_gem_bo_reference_locked(target_bo);
+    drm_intel_gem_bo_reference(target_bo);
 
     bo_gem->reloc_count++;