[drm-intel:for-linux-next-gt 1/4] drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c:2680 guc_context_policy_init_v70() warn: variable dereferenced before check 'ce' (see line 2663)

[Dan Carpenter]

tree:   git://anongit.freedesktop.org/drm-intel for-linux-next-gt
head:   7ad6a8fae597af7fae5193efc73276609337c360
commit: cec82816d0d018f178b9b7f88fe4bf80d66954e9 [1/4] drm/i915/guc: Use context hints for GT frequency
config: i386-randconfig-141-20240309 (https://download.01.org/0day-ci/archive/20240310/202403101225.7AheJhZJ-lkp@intel.com/config)
compiler: gcc-12 (Debian 12.2.0-14) 12.2.0

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 at intel.com>
| Reported-by: Dan Carpenter <dan.carpenter at linaro.org>
| Closes: https://lore.kernel.org/r/202403101225.7AheJhZJ-lkp@intel.com/

New smatch warnings:
drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c:2680 guc_context_policy_init_v70() warn: variable dereferenced before check 'ce' (see line 2663)

vim +/ce +2680 drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c

774ce1510e6ccb Daniele Ceraolo Spurio 2022-07-18  2661  static int guc_context_policy_init_v70(struct intel_context *ce, bool loop)
2584b3549f4c40 John Harrison          2022-04-12  2662  {
2584b3549f4c40 John Harrison          2022-04-12 @2663  	struct intel_engine_cs *engine = ce->engine;
                                                                                                 ^^^^^^^^^^
Unchecked dereference

3f2f20da79b208 Andi Shyti             2023-12-29  2664  	struct intel_guc *guc = gt_to_guc(engine->gt);
2584b3549f4c40 John Harrison          2022-04-12  2665  	struct context_policy policy;
2584b3549f4c40 John Harrison          2022-04-12  2666  	u32 execution_quantum;
2584b3549f4c40 John Harrison          2022-04-12  2667  	u32 preemption_timeout;
cec82816d0d018 Vinay Belgaumkar       2024-03-05  2668  	u32 slpc_ctx_freq_req = 0;
2584b3549f4c40 John Harrison          2022-04-12  2669  	unsigned long flags;
2584b3549f4c40 John Harrison          2022-04-12  2670  	int ret;
3a4bfa091c46e9 Rahul Kumar Singh      2021-07-26  2671  
7935785240508c John Harrison          2021-07-26  2672  	/* NB: For both of these, zero means disabled. */
568944af44e753 John Harrison          2022-10-06  2673  	GEM_BUG_ON(overflows_type(engine->props.timeslice_duration_ms * 1000,
568944af44e753 John Harrison          2022-10-06  2674  				  execution_quantum));
568944af44e753 John Harrison          2022-10-06  2675  	GEM_BUG_ON(overflows_type(engine->props.preempt_timeout_ms * 1000,
568944af44e753 John Harrison          2022-10-06  2676  				  preemption_timeout));
2584b3549f4c40 John Harrison          2022-04-12  2677  	execution_quantum = engine->props.timeslice_duration_ms * 1000;
2584b3549f4c40 John Harrison          2022-04-12  2678  	preemption_timeout = engine->props.preempt_timeout_ms * 1000;
2584b3549f4c40 John Harrison          2022-04-12  2679  
cec82816d0d018 Vinay Belgaumkar       2024-03-05 @2680  	if (ce && (ce->flags & BIT(CONTEXT_LOW_LATENCY)))
                                                                    ^^
NULL check is too late.

cec82816d0d018 Vinay Belgaumkar       2024-03-05  2681  		slpc_ctx_freq_req |= SLPC_CTX_FREQ_REQ_IS_COMPUTE;
cec82816d0d018 Vinay Belgaumkar       2024-03-05  2682  
2584b3549f4c40 John Harrison          2022-04-12  2683  	__guc_context_policy_start_klv(&policy, ce->guc_id.id);
2584b3549f4c40 John Harrison          2022-04-12  2684  
2584b3549f4c40 John Harrison          2022-04-12  2685  	__guc_context_policy_add_priority(&policy, ce->guc_state.prio);
2584b3549f4c40 John Harrison          2022-04-12  2686  	__guc_context_policy_add_execution_quantum(&policy, execution_quantum);
2584b3549f4c40 John Harrison          2022-04-12  2687  	__guc_context_policy_add_preemption_timeout(&policy, preemption_timeout);
cec82816d0d018 Vinay Belgaumkar       2024-03-05  2688  	__guc_context_policy_add_slpc_ctx_freq_req(&policy, slpc_ctx_freq_req);
2584b3549f4c40 John Harrison          2022-04-12  2689  
2584b3549f4c40 John Harrison          2022-04-12  2690  	if (engine->flags & I915_ENGINE_WANT_FORCED_PREEMPTION)
2584b3549f4c40 John Harrison          2022-04-12  2691  		__guc_context_policy_add_preempt_to_idle(&policy, 1);
2584b3549f4c40 John Harrison          2022-04-12  2692  
2584b3549f4c40 John Harrison          2022-04-12  2693  	ret = __guc_context_set_context_policies(guc, &policy, loop);
2584b3549f4c40 John Harrison          2022-04-12  2694  
2584b3549f4c40 John Harrison          2022-04-12  2695  	spin_lock_irqsave(&ce->guc_state.lock, flags);
6c82c75230b87d Daniele Ceraolo Spurio 2022-07-27  2696  	if (ret != 0)
2584b3549f4c40 John Harrison          2022-04-12  2697  		set_context_policy_required(ce);
2584b3549f4c40 John Harrison          2022-04-12  2698  	else
2584b3549f4c40 John Harrison          2022-04-12  2699  		clr_context_policy_required(ce);
2584b3549f4c40 John Harrison          2022-04-12  2700  	spin_unlock_irqrestore(&ce->guc_state.lock, flags);
2584b3549f4c40 John Harrison          2022-04-12  2701  
2584b3549f4c40 John Harrison          2022-04-12  2702  	return ret;
3a4cdf1982f05d Matthew Brost          2021-07-21  2703  }

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