[PATCH 3/8] drm/i915/gtt: Extract unwind to separate function for gen6_alloc_va_range

["Michał Winiarski" <michal.winiarski@intel.com>]

In case of error during allocation we should free the entries allocated
during the current "transaction".
We can't simply reuse the clear_range, since for gen6 we're not
shrinking ppgtt. We can extract unwind to a function though, and use
range rather than bitmaps.

Cc: Arkadiusz Hiler <arkadiusz.hiler@intel.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Cc: Michel Thierry <michel.thierry@intel.com>
Cc: Mika Kuoppala <mika.kuoppala@intel.com>
Signed-off-by: Michał Winiarski <michal.winiarski@intel.com>
---
 drivers/gpu/drm/i915/i915_gem_gtt.c | 33 +++++++++++++++++++++------------
 1 file changed, 21 insertions(+), 12 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_gem_gtt.c b/drivers/gpu/drm/i915/i915_gem_gtt.c
index 49e1006..f760c3e 100644
--- a/drivers/gpu/drm/i915/i915_gem_gtt.c
+++ b/drivers/gpu/drm/i915/i915_gem_gtt.c
@@ -1917,6 +1917,23 @@ static void gen6_ppgtt_insert_entries(struct i915_address_space *vm,
 		kunmap_px(ppgtt, pt_vaddr);
 }
 
+static void gen6_ppgtt_unwind_pd(struct i915_address_space *vm,
+				 struct i915_page_directory *pd,
+				 uint64_t start, uint64_t length) {
+
+	struct i915_page_table *pt;
+	uint64_t pde;
+
+	/* We're only using this for cleanup on PT allocation failure,
+	 * and since in this case scratch_pt is already encoded in pde there's
+	 * no need to call gen6_write_pde.
+	 */
+	gen6_for_each_pde(pt, pd, start, length, pde) {
+		pd->page_table[pde] = vm->scratch_pt;
+		free_pt(vm->i915, pt);
+	}
+}
+
 static int gen6_alloc_va_range(struct i915_address_space *vm,
 			       uint64_t start, uint64_t length)
 {
@@ -1954,7 +1971,10 @@ static int gen6_alloc_va_range(struct i915_address_space *vm,
 		pt = alloc_pt(dev_priv);
 		if (IS_ERR(pt)) {
 			ret = PTR_ERR(pt);
-			goto unwind_out;
+			gen6_ppgtt_unwind_pd(vm, &ppgtt->pd,
+					     start_save, start - start_save);
+			mark_tlbs_dirty(ppgtt);
+			return ret;
 		}
 
 		gen6_initialize_pt(vm, pt);
@@ -1993,17 +2013,6 @@ static int gen6_alloc_va_range(struct i915_address_space *vm,
 
 	mark_tlbs_dirty(ppgtt);
 	return 0;
-
-unwind_out:
-	for_each_set_bit(pde, new_page_tables, I915_PDES) {
-		struct i915_page_table *pt = ppgtt->pd.page_table[pde];
-
-		ppgtt->pd.page_table[pde] = vm->scratch_pt;
-		free_pt(dev_priv, pt);
-	}
-
-	mark_tlbs_dirty(ppgtt);
-	return ret;
 }
 
 static int gen6_init_scratch(struct i915_address_space *vm)
-- 
2.7.4

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