From 635f56c342cd195a8059f24296fe7fd795aaa33d Mon Sep 17 00:00:00 2001
From: Imre Deak <imre.deak@intel.com>
Date: Fri, 14 Jul 2017 18:12:41 +0300
Subject: [PATCH] drm/i915: Fix error checking/locking in perf/lookup_context()
Git-commit: 635f56c342cd195a8059f24296fe7fd795aaa33d
Patch-mainline: v4.14-rc1
References: FATE#322643 bsc#1055900

1acfc104cdf8 missed to convert this one caller to be lockless. The side
effect of that was that the error check in lookup_context() became
incorrect. Convert now this caller too.

Fixes: 1acfc104cdf ("drm/i915: Enable rcu-only context lookups")
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Lionel Landwerlin <lionel.g.landwerlin@intel.com>
Signed-off-by: Imre Deak <imre.deak@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20170714151242.517-1-imre.deak@intel.com
Acked-by: Takashi Iwai <tiwai@suse.de>

---
 drivers/gpu/drm/i915/i915_perf.c |   32 +++++---------------------------
 1 file changed, 5 insertions(+), 27 deletions(-)

--- a/drivers/gpu/drm/i915/i915_perf.c
+++ b/drivers/gpu/drm/i915/i915_perf.c
@@ -2483,27 +2483,6 @@ static const struct file_operations fops
 };
 
 
-static struct i915_gem_context *
-lookup_context(struct drm_i915_private *dev_priv,
-	       struct drm_i915_file_private *file_priv,
-	       u32 ctx_user_handle)
-{
-	struct i915_gem_context *ctx;
-	int ret;
-
-	ret = i915_mutex_lock_interruptible(&dev_priv->drm);
-	if (ret)
-		return ERR_PTR(ret);
-
-	ctx = i915_gem_context_lookup(file_priv, ctx_user_handle);
-	if (!IS_ERR(ctx))
-		i915_gem_context_get(ctx);
-
-	mutex_unlock(&dev_priv->drm.struct_mutex);
-
-	return ctx;
-}
-
 /**
  * i915_perf_open_ioctl_locked - DRM ioctl() for userspace to open a stream FD
  * @dev_priv: i915 device instance
@@ -2545,12 +2524,11 @@ i915_perf_open_ioctl_locked(struct drm_i
 		u32 ctx_handle = props->ctx_handle;
 		struct drm_i915_file_private *file_priv = file->driver_priv;
 
-		specific_ctx = lookup_context(dev_priv, file_priv, ctx_handle);
-		if (IS_ERR(specific_ctx)) {
-			ret = PTR_ERR(specific_ctx);
-			if (ret != -EINTR)
-				DRM_DEBUG("Failed to look up context with ID %u for opening perf stream\n",
-					  ctx_handle);
+		specific_ctx = i915_gem_context_lookup(file_priv, ctx_handle);
+		if (!specific_ctx) {
+			DRM_DEBUG("Failed to look up context with ID %u for opening perf stream\n",
+				  ctx_handle);
+			ret = -ENOENT;
 			goto err;
 		}
 	}