Re: [PATCH 2/2] drm: bridge: ti-sn65dsi83: Add error recovery mechanism

[Dan Carpenter <dan.carpenter@linaro.org>]

Hi Herve,

kernel test robot noticed the following build warnings:

https://git-scm.com/docs/git-format-patch#_base_tree_information]

url:    https://github.com/intel-lab-lkp/linux/commits/Herve-Codina/dt-bindings-display-bridge-sn65dsi83-Add-interrupt/20241024-175758
base:   https://git.kernel.org/pub/scm/linux/kernel/git/robh/linux.git for-next
patch link:    https://lore.kernel.org/r/20241024095539.1637280-3-herve.codina%40bootlin.com
patch subject: [PATCH 2/2] drm: bridge: ti-sn65dsi83: Add error recovery mechanism
config: csky-randconfig-r073-20241026 (https://download.01.org/0day-ci/archive/20241026/202410262052.CRR7XezU-lkp@intel.com/config)
compiler: csky-linux-gcc (GCC) 14.1.0

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Reported-by: Dan Carpenter <dan.carpenter@linaro.org>
| Closes: https://lore.kernel.org/r/202410262052.CRR7XezU-lkp@intel.com/

smatch warnings:
drivers/gpu/drm/bridge/ti-sn65dsi83.c:360 sn65dsi83_reset_pipeline() error: uninitialized symbol 'state'.

vim +/state +360 drivers/gpu/drm/bridge/ti-sn65dsi83.c

caeb909b9ed830 Herve Codina 2024-10-24  330  static int sn65dsi83_reset_pipeline(struct sn65dsi83 *sn65dsi83)
caeb909b9ed830 Herve Codina 2024-10-24  331  {
caeb909b9ed830 Herve Codina 2024-10-24  332  	struct drm_device *dev = sn65dsi83->bridge.dev;
caeb909b9ed830 Herve Codina 2024-10-24  333  	struct drm_modeset_acquire_ctx ctx;
caeb909b9ed830 Herve Codina 2024-10-24  334  	struct drm_atomic_state *state;

Almost everyone has their compiler set to zero out stack variables these days.
You should set this to struct drm_atomic_state *state = ERR_PTR(-EINVAL);.

caeb909b9ed830 Herve Codina 2024-10-24  335  	int err;
caeb909b9ed830 Herve Codina 2024-10-24  336  
caeb909b9ed830 Herve Codina 2024-10-24  337  	/* Use operation done in drm_atomic_helper_suspend() followed by
caeb909b9ed830 Herve Codina 2024-10-24  338  	 * operation done in drm_atomic_helper_resume() but without releasing
caeb909b9ed830 Herve Codina 2024-10-24  339  	 * the lock between suspend()/resume()
caeb909b9ed830 Herve Codina 2024-10-24  340  	 */
caeb909b9ed830 Herve Codina 2024-10-24  341  
caeb909b9ed830 Herve Codina 2024-10-24  342  	DRM_MODESET_LOCK_ALL_BEGIN(dev, ctx, 0, err);

This macro has a goto in it.

caeb909b9ed830 Herve Codina 2024-10-24  343  
caeb909b9ed830 Herve Codina 2024-10-24  344  	state = drm_atomic_helper_duplicate_state(dev, &ctx);
caeb909b9ed830 Herve Codina 2024-10-24  345  	if (IS_ERR(state)) {
caeb909b9ed830 Herve Codina 2024-10-24  346  		err = PTR_ERR(state);
caeb909b9ed830 Herve Codina 2024-10-24  347  		goto unlock;
caeb909b9ed830 Herve Codina 2024-10-24  348  	}
caeb909b9ed830 Herve Codina 2024-10-24  349  
caeb909b9ed830 Herve Codina 2024-10-24  350  	err = drm_atomic_helper_disable_all(dev, &ctx);
caeb909b9ed830 Herve Codina 2024-10-24  351  	if (err < 0)
caeb909b9ed830 Herve Codina 2024-10-24  352  		goto unlock;
caeb909b9ed830 Herve Codina 2024-10-24  353  
caeb909b9ed830 Herve Codina 2024-10-24  354  	drm_mode_config_reset(dev);
caeb909b9ed830 Herve Codina 2024-10-24  355  
caeb909b9ed830 Herve Codina 2024-10-24  356  	err = drm_atomic_helper_commit_duplicated_state(state, &ctx);
caeb909b9ed830 Herve Codina 2024-10-24  357  
caeb909b9ed830 Herve Codina 2024-10-24  358  unlock:
caeb909b9ed830 Herve Codina 2024-10-24  359  	DRM_MODESET_LOCK_ALL_END(dev, ctx, err);
caeb909b9ed830 Herve Codina 2024-10-24 @360  	if (!IS_ERR(state))
caeb909b9ed830 Herve Codina 2024-10-24  361  		drm_atomic_state_put(state);

Calling drm_atomic_state_put(NULL) leads to an Oops.

caeb909b9ed830 Herve Codina 2024-10-24  362  	return err;
caeb909b9ed830 Herve Codina 2024-10-24  363  }

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