drm/i915: Fix preallocated barrier list append

Only the first and the last nodes were being added to
ref->preallocated_barriers.

Renaming variables to make it more easy to read.

Fixes: 841350223816 ("drm/i915/gt: Drop mutex serialisation between context pin/unpin")
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Signed-off-by: José Roberto de Souza <jose.souza@intel.com>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Link: https://patchwork.freedesktop.org/patch/msgid/20200129232345.84512-1-jose.souza@intel.com

diff --git a/drivers/gpu/drm/i915/i915_active.c b/drivers/gpu/drm/i915/i915_active.c
index 9d6830885d2e18c9a4ba45eede3d72be9af6f98d..3d2e7cf55e52479f4d1cbc83fe97d94f05ad7653 100644 (file)
--- a/drivers/gpu/drm/i915/i915_active.c
+++ b/drivers/gpu/drm/i915/i915_active.c
@@ -607,7 +607,7 @@ int i915_active_acquire_preallocate_barrier(struct i915_active *ref,
                                            struct intel_engine_cs *engine)
 {
        intel_engine_mask_t tmp, mask = engine->mask;
-       struct llist_node *pos = NULL, *next;
+       struct llist_node *first = NULL, *last = NULL;
        struct intel_gt *gt = engine->gt;
        int err;
 
@@ -626,6 +626,7 @@ int i915_active_acquire_preallocate_barrier(struct i915_active *ref,
        GEM_BUG_ON(!mask);
        for_each_engine_masked(engine, gt, mask, tmp) {
                u64 idx = engine->kernel_context->timeline->fence_context;
+               struct llist_node *prev = first;
                struct active_node *node;
 
                node = reuse_idle_barrier(ref, idx);
@@ -659,23 +660,23 @@ int i915_active_acquire_preallocate_barrier(struct i915_active *ref,
                GEM_BUG_ON(rcu_access_pointer(node->base.fence) != ERR_PTR(-EAGAIN));
 
                GEM_BUG_ON(barrier_to_engine(node) != engine);
-               next = barrier_to_ll(node);
-               next->next = pos;
-               if (!pos)
-                       pos = next;
+               first = barrier_to_ll(node);
+               first->next = prev;
+               if (!last)
+                       last = first;
                intel_engine_pm_get(engine);
        }
 
        GEM_BUG_ON(!llist_empty(&ref->preallocated_barriers));
-       llist_add_batch(next, pos, &ref->preallocated_barriers);
+       llist_add_batch(first, last, &ref->preallocated_barriers);
 
        return 0;
 
 unwind:
-       while (pos) {
-               struct active_node *node = barrier_from_ll(pos);
+       while (first) {
+               struct active_node *node = barrier_from_ll(first);
 
-               pos = pos->next;
+               first = first->next;
 
                atomic_dec(&ref->count);
                intel_engine_pm_put(barrier_to_engine(node));