Hello Chris Wilson,
This is a semi-automatic email about new static checker warnings.
The patch c286558f5853: "drm/i915/gt: Use i915_vm_put on ppgtt_create
error paths" from Sep 26, 2022, leads to the following Smatch
complaint:
drivers/gpu/drm/i915/gt/gen6_ppgtt.c:274 gen6_ppgtt_cleanup()
warn: variable dereferenced before check 'ppgtt->base.pd' (see line 271)
drivers/gpu/drm/i915/gt/gen6_ppgtt.c
256 static void gen6_ppgtt_free_pd(struct gen6_ppgtt *ppgtt)
257 {
258 struct i915_page_directory * const pd = ppgtt->base.pd;
^^
pd is ppgtt->base.pd.
259 struct i915_page_table *pt;
260 u32 pde;
261
262 gen6_for_all_pdes(pt, pd, pde)
^^
There is an unchecked dereference inside this loop macro.
263 if (pt)
264 free_pt(&ppgtt->base.vm, pt);
265 }
266
267 static void gen6_ppgtt_cleanup(struct i915_address_space *vm)
268 {
269 struct gen6_ppgtt *ppgtt = to_gen6_ppgtt(i915_vm_to_ppgtt(vm));
270
271 gen6_ppgtt_free_pd(ppgtt);
^^^^^^^^^^^^^^^^^^^^^^^^^^
272 free_scratch(vm);
273
274 if (ppgtt->base.pd)
^^^^^^^^^^^^^^
Checked after an unchecked dereference.
275 free_pd(&ppgtt->base.vm, ppgtt->base.pd);
276
277 mutex_destroy(&ppgtt->flush);
278 }
regards,
dan carpenter
