On Thu, 4 Jul 2019 at 11:43, Chris Wilson <[email protected]> wrote:
>
> Matthew pointed out that we could face a double failure with concurrent
> allocations/frees, and so the assumption that the local var alloc was
> NULL was fraught with danger. Rather than complicate the error paths too
> much to add a second local for a second free, just do the second free
> earlier on the unwind path.
>
> Reported-by: Matthew Auld <[email protected]>
> Signed-off-by: Chris Wilson <[email protected]>
> Cc: Matthew Auld <[email protected]>
I quite liked your previous pattern:
@@ -1442,6 +1442,7 @@ static int gen8_ppgtt_alloc_pdp(struct
i915_address_space *vm,
{
struct i915_page_directory *pd, *alloc = NULL;
u64 from = start;
+ bool free = false;
unsigned int pdpe;
int ret = 0;
@@ -1489,10 +1490,11 @@ static int gen8_ppgtt_alloc_pdp(struct
i915_address_space *vm,
gen8_ppgtt_set_pdpe(pdp, vm->scratch_pd, pdpe);
GEM_BUG_ON(!atomic_read(&pdp->used));
atomic_dec(&pdp->used);
- GEM_BUG_ON(alloc);
- alloc = pd; /* defer the free to after the lock */
+ free = true;
}
spin_unlock(&pdp->lock);
+ if (free)
+ free_pd(vm, pd);
unwind:
gen8_ppgtt_clear_pdp(vm, pdp, from, start - from);
out:
Anyway,
Reviewed-by: Matthew Auld <[email protected]>
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