[Intel-gfx] [PATCH] drm/i915: Don't deref context->file_priv ERR_PTR upon reset

[Chris Wilson]

When a user context is closed, it's file_priv backpointer is replaced by
ERR_PTR(-EBADF); be careful not to chase this invalid pointer after a
hang and a GPU reset.

Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
Fixes: b083a0870c79 ("drm/i915: Add per client max context ban limit")
Cc: Mika Kuoppala <mika.kuoppala at intel.com>
---
 drivers/gpu/drm/i915/i915_gem.c | 12 ++++--------
 1 file changed, 4 insertions(+), 8 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index b850e66c2f83..d75196b86693 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -2647,16 +2647,12 @@ static void i915_gem_context_mark_guilty(struct i915_gem_context *ctx)
 			 ctx->name, ctx->ban_score,
 			 yesno(ctx->banned));
 
-	if (!ctx->file_priv)
+	if (!ctx->banned || IS_ERR_OR_NULL(ctx->file_priv))
 		return;
 
-	if (ctx->banned) {
-		ctx->file_priv->context_bans++;
-
-		DRM_DEBUG_DRIVER("client %s has has %d context banned\n",
-				 ctx->name,
-				 ctx->file_priv->context_bans);
-	}
+	ctx->file_priv->context_bans++;
+	DRM_DEBUG_DRIVER("client %s has had %d context banned\n",
+			 ctx->name, ctx->file_priv->context_bans);
 }
 
 static void i915_gem_context_mark_innocent(struct i915_gem_context *ctx)
-- 
2.10.2