On 29/06/2017 14:49, Chris Wilson wrote:
When computing a hash for looking up relcoation target handles in an
execbuf, we start with a large size for the hashtable and proceed to
reduce it until the allocation suceeds. The final attempt is with an
order of 0 (i.e. a single element). This means that we then pass bits=0
to hash_32() which then computes "hash >> (32 - 0)" to lookup the single
element. Right shifting by a value the width of the operand is
undefined, so limit the smallest hash table we use to order 1.
Fixes: 4ff4b44cbb70 ("drm/i915: Store a direct lookup from object handle to vma")
Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
Cc: Joonas Lahtinen <joonas.lahtinen@xxxxxxxxxxxxxxx>
Cc: Tvrtko Ursulin <tvrtko.ursulin@xxxxxxxxx>
---
drivers/gpu/drm/i915/i915_gem_execbuffer.c | 22 +++++++++++-----------
1 file changed, 11 insertions(+), 11 deletions(-)
diff --git a/drivers/gpu/drm/i915/i915_gem_execbuffer.c b/drivers/gpu/drm/i915/i915_gem_execbuffer.c
index 718bb75ad387..54791bcb8ccb 100644
--- a/drivers/gpu/drm/i915/i915_gem_execbuffer.c
+++ b/drivers/gpu/drm/i915/i915_gem_execbuffer.c
@@ -296,12 +296,8 @@ static int eb_create(struct i915_execbuffer *eb)
break;
} while (--size);
- if (unlikely(!eb->buckets)) {
- eb->buckets = kzalloc(sizeof(struct hlist_head),
- GFP_TEMPORARY);
Want to maybe drop the NORETRY | NOWARN from the remaining allocation
now? Wasn't it recently discussed that it is to feeble in it's attempts
to allocate?
- if (unlikely(!eb->buckets))
- return -ENOMEM;
- }
+ if (unlikely(!eb->buckets))
+ return -ENOMEM;
eb->lut_size = size;
} else {
@@ -453,7 +449,7 @@ eb_add_vma(struct i915_execbuffer *eb,
return err;
}
- if (eb->lut_size >= 0) {
+ if (eb->lut_size > 0) {
vma->exec_handle = entry->handle;
hlist_add_head(&vma->exec_node,
&eb->buckets[hash_32(entry->handle,
@@ -897,7 +893,7 @@ static void eb_release_vmas(const struct i915_execbuffer *eb)
static void eb_reset_vmas(const struct i915_execbuffer *eb)
{
eb_release_vmas(eb);
- if (eb->lut_size >= 0)
+ if (eb->lut_size > 0)
memset(eb->buckets, 0,
sizeof(struct hlist_head) << eb->lut_size);
}
@@ -906,7 +902,7 @@ static void eb_destroy(const struct i915_execbuffer *eb)
{
GEM_BUG_ON(eb->reloc_cache.rq);
- if (eb->lut_size >= 0)
+ if (eb->lut_size > 0)
kfree(eb->buckets);
}
@@ -2185,8 +2181,11 @@ i915_gem_do_execbuffer(struct drm_device *dev,
}
}
- if (eb_create(&eb))
- return -ENOMEM;
+ err = eb_create(&eb);
+ if (err)
+ goto err_out_fence;
+
+ GEM_BUG_ON(!eb.lut_size);
err = eb_select_context(&eb);
if (unlikely(err))
@@ -2346,6 +2345,7 @@ i915_gem_do_execbuffer(struct drm_device *dev,
i915_gem_context_put(eb.ctx);
err_destroy:
eb_destroy(&eb);
+err_out_fence:
if (out_fence_fd != -1)
put_unused_fd(out_fence_fd);
err_in_fence:
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@xxxxxxxxx>
Regards,
Tvrtko
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