[PATCH] drm/i915: Fix bug in user proto-context creation that leaked contexts

[Matthew Brost]

Set number of engines before attempting to create contexts so the
function free_engines can clean up properly. Also check return of
alloc_engines for NULL.

v2:
 (Tvrtko)
  - Send as stand alone patch
 (John Harrison)
  - Check for alloc_engines returning NULL

Cc: Jason Ekstrand <jason at jlekstrand.net>
Fixes: d4433c7600f7 ("drm/i915/gem: Use the proto-context to handle create parameters (v5)")
Signed-off-by: Matthew Brost <matthew.brost at intel.com>
Cc: <stable at vger.kernel.org>
---
 drivers/gpu/drm/i915/gem/i915_gem_context.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/i915/gem/i915_gem_context.c b/drivers/gpu/drm/i915/gem/i915_gem_context.c
index c2ab0e22db0a..9627c7aac6a3 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_context.c
+++ b/drivers/gpu/drm/i915/gem/i915_gem_context.c
@@ -898,6 +898,11 @@ static struct i915_gem_engines *user_engines(struct i915_gem_context *ctx,
 	unsigned int n;
 
 	e = alloc_engines(num_engines);
+	if (!e) {
+		return ERR_PTR(-ENOMEM);
+	}
+	e->num_engines = num_engines;
+
 	for (n = 0; n < num_engines; n++) {
 		struct intel_context *ce;
 		int ret;
@@ -931,7 +936,6 @@ static struct i915_gem_engines *user_engines(struct i915_gem_context *ctx,
 			goto free_engines;
 		}
 	}
-	e->num_engines = num_engines;
 
 	return e;
 
-- 
2.32.0