[linux-next:master 9115/11394] drivers/gpu/drm/xe/xe_ggtt.c:256 ggtt_invalidate_gt_tlb() warn: variable dereferenced before check 'gt' (see line 253)

[linux-next:master 9115/11394] drivers/gpu/drm/xe/xe_ggtt.c:256 ggtt_invalidate_gt_tlb() warn: variable dereferenced before check 'gt' (see line 253)

[kernel test robot]

BCC: lkp@intel.com
CC: oe-kbuild-all@lists.linux.dev
CC: Linux Memory Management List <linux-mm@kvack.org>
TO: Matthew Brost <matthew.brost@intel.com>
CC: Rodrigo Vivi <rodrigo.vivi@intel.com>

tree:   https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git master
head:   1870cdc0e8dee32e3c221704a2977898ba4c10e8
commit: 3121fed0c51beb8ea7b18ab2ceff1ac9e358ac53 [9115/11394] drm/xe: Cleanup some layering in GGTT
:::::: branch date: 2 days ago
:::::: commit date: 8 days ago
config: x86_64-randconfig-161-20240302 (https://download.01.org/0day-ci/archive/20240303/202403031315.uPyTvJYB-lkp@intel.com/config)
compiler: gcc-9 (Debian 9.3.0-22) 9.3.0

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 <error27@gmail.com>
| Closes: https://lore.kernel.org/r/202403031315.uPyTvJYB-lkp@intel.com/

smatch warnings:
drivers/gpu/drm/xe/xe_ggtt.c:256 ggtt_invalidate_gt_tlb() warn: variable dereferenced before check 'gt' (see line 253)

vim +/gt +256 drivers/gpu/drm/xe/xe_ggtt.c

dd08ebf6c3525a Matthew Brost 2023-03-30  250  
d78a4778195079 Matt Roper    2023-06-01  251  static void ggtt_invalidate_gt_tlb(struct xe_gt *gt)
dd08ebf6c3525a Matthew Brost 2023-03-30  252  {
3121fed0c51beb Matthew Brost 2024-02-22 @253  	struct xe_device *xe = gt_to_xe(gt);
3121fed0c51beb Matthew Brost 2024-02-22  254  	int err;
3121fed0c51beb Matthew Brost 2024-02-22  255  
d78a4778195079 Matt Roper    2023-06-01 @256  	if (!gt)
d78a4778195079 Matt Roper    2023-06-01  257  		return;
ad703e06376d5d Matt Roper    2023-06-01  258  
933b78d678213f Matt Roper    2023-06-01  259  	/*
933b78d678213f Matt Roper    2023-06-01  260  	 * Invalidation can happen when there's no in-flight work keeping the
933b78d678213f Matt Roper    2023-06-01  261  	 * GT awake.  We need to explicitly grab forcewake to ensure the GT
933b78d678213f Matt Roper    2023-06-01  262  	 * and GuC are accessible.
933b78d678213f Matt Roper    2023-06-01  263  	 */
933b78d678213f Matt Roper    2023-06-01  264  	xe_force_wake_get(gt_to_fw(gt), XE_FW_GT);
3121fed0c51beb Matthew Brost 2024-02-22  265  	err = xe_gt_tlb_invalidation_ggtt(gt);
3121fed0c51beb Matthew Brost 2024-02-22  266  	if (err)
3121fed0c51beb Matthew Brost 2024-02-22  267  		drm_warn(&xe->drm, "xe_gt_tlb_invalidation_ggtt error=%d", err);
933b78d678213f Matt Roper    2023-06-01  268  	xe_force_wake_put(gt_to_fw(gt), XE_FW_GT);
dd08ebf6c3525a Matthew Brost 2023-03-30  269  }
dd08ebf6c3525a Matthew Brost 2023-03-30  270  

:::::: The code at line 256 was first introduced by commit
:::::: d78a4778195079e0b2820550efeecb7b25fa764a drm/xe: Invalidate TLB on all affected GTs during GGTT updates

:::::: TO: Matt Roper <matthew.d.roper@intel.com>
:::::: CC: Rodrigo Vivi <rodrigo.vivi@intel.com>

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