linux-kernel - [PATCH] drm/loongson: Remove a useless check in cursor_plane_atomic_async

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Date:   Mon, 10 Jul 2023 18:24:11 +0800
From:   Sui Jingfeng <suijingfeng@...ngson.cn>
To:     Sui Jingfeng <suijingfeng@...ngson.cn>,
        David Airlie <airlied@...il.com>,
        Daniel Vetter <daniel@...ll.ch>,
        Thomas Zimmermann <tzimmermann@...e.de>,
        Li Yi <liyi@...ngson.cn>
Cc:     dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
        loongson-kernel@...ts.loongnix.cn,
        Dan Carpenter <dan.carpenter@...aro.org>
Subject: [PATCH] drm/loongson: Remove a useless check in cursor_plane_atomic_async_check()

Because smatch warnings:

drivers/gpu/drm/loongson/lsdc_plane.c:199
lsdc_cursor_plane_atomic_async_check()
warn: variable dereferenced before check 'state' (see line 180)

vim +/state +199 drivers/gpu/drm/loongson/lsdc_plane.c

174  static int
     lsdc_cursor_plane_atomic_async_check(struct drm_plane *plane,
175                                       struct drm_atomic_state *state)
176  {
177          struct drm_plane_state *new_state;
178          struct drm_crtc_state *crtc_state;
179
180          new_state = drm_atomic_get_new_plane_state(state, plane);
                                                        ^^^^^
state is dereferenced inside this function

181
182  if (!plane->state || !plane->state->fb) {
183          drm_dbg(plane->dev, "%s: state is NULL\n", plane->name);
184                  return -EINVAL;
185  }
186
187  if (new_state->crtc_w != new_state->crtc_h) {
188          drm_dbg(plane->dev, "unsupported cursor size: %ux%u\n",
189                  new_state->crtc_w, new_state->crtc_h);
190          return -EINVAL;
191  }
192
193  if (new_state->crtc_w != 64 && new_state->crtc_w != 32) {
194          drm_dbg(plane->dev, "unsupported cursor size: %ux%u\n",
195                  new_state->crtc_w, new_state->crtc_h);
196          return -EINVAL;
197  }
198
199  if (state) {
         ^^^^^
Checked too late!

Reported-by: Dan Carpenter <dan.carpenter@...aro.org>
Closes: https://lore.kernel.org/r/202307100423.rV7D05Uq-lkp@intel.com/
Signed-off-by: Sui Jingfeng <suijingfeng@...ngson.cn>
---
 drivers/gpu/drm/loongson/lsdc_plane.c | 8 +-------
 1 file changed, 1 insertion(+), 7 deletions(-)

diff --git a/drivers/gpu/drm/loongson/lsdc_plane.c b/drivers/gpu/drm/loongson/lsdc_plane.c
index 2ab3db982aa3..0d5094633222 100644
--- a/drivers/gpu/drm/loongson/lsdc_plane.c
+++ b/drivers/gpu/drm/loongson/lsdc_plane.c
@@ -196,13 +196,7 @@ static int lsdc_cursor_plane_atomic_async_check(struct drm_plane *plane,
 		return -EINVAL;
 	}
 
-	if (state) {
-		crtc_state = drm_atomic_get_existing_crtc_state(state, new_state->crtc);
-	} else {
-		crtc_state = plane->crtc->state;
-		drm_dbg(plane->dev, "%s: atomic state is NULL\n", plane->name);
-	}
-
+	crtc_state = drm_atomic_get_existing_crtc_state(state, new_state->crtc);
 	if (!crtc_state->active)
 		return -EINVAL;
 
-- 
2.34.1