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drm/pagemap_util: Ensure proper cache lock management on free

For the sake of consistency, ensure that the cache lock is always
unlocked after drm_pagemap_cache_fini. Spinlocks typically disable
preemption and if the code-path missing the unlock is hit, preemption
will remain disabled even if the lock is subsequently freed.

Fixes static analysis issue.

v2:
- Use requested code flow (Maarten)

v3:
- Clear cache->dpagemap (Matt Brost, Maarten)

v4:
- Reword commit message (Thomas)

Fixes: 77f14f2f2d73f ("drm/pagemap: Add a drm_pagemap cache and shrinker")
Signed-off-by: Jonathan Cavitt <jonathan.cavitt@intel.com>
Reviewed-by: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Reviewed-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Cc: Thomas Hellstrom <thomas.hellstrom@linux.intel.com>
Cc: Matthew Brost <matthew.brost@intel.com>
Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Signed-off-by: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Link: https://patch.msgid.link/20260316151555.7553-2-jonathan.cavitt@intel.com

authored by

Jonathan Cavitt and committed by
Thomas Hellström 67253b28 74ef7844

+5 -9
+5 -9
drivers/gpu/drm/drm_pagemap_util.c
··· 65 65 drm_dbg(cache->shrinker->drm, "Destroying dpagemap cache.\n"); 66 66 spin_lock(&cache->lock); 67 67 dpagemap = cache->dpagemap; 68 - if (!dpagemap) { 69 - spin_unlock(&cache->lock); 70 - goto out; 71 - } 68 + cache->dpagemap = NULL; 69 + if (dpagemap && !drm_pagemap_shrinker_cancel(dpagemap)) 70 + dpagemap = NULL; 71 + spin_unlock(&cache->lock); 72 72 73 - if (drm_pagemap_shrinker_cancel(dpagemap)) { 74 - cache->dpagemap = NULL; 75 - spin_unlock(&cache->lock); 73 + if (dpagemap) 76 74 drm_pagemap_destroy(dpagemap, false); 77 - } 78 75 79 - out: 80 76 mutex_destroy(&cache->lookup_mutex); 81 77 kfree(cache); 82 78 }