On Fri, Jul 02, 2021 at 11:32:45AM +0100, Matthew Auld wrote: > On Fri, 2 Jul 2021 at 09:45, Dan Carpenter wrote: > > > > tree: git://anongit.freedesktop.org/drm-intel drm-intel-gt-next > > head: 5cd57f676bb946a00275408f0dd0d75dbc466d25 > > commit: cf586021642d8017cde111b7dd1ba86224e9da51 [8/14] drm/i915/gt: Pipelined page migration > > config: x86_64-randconfig-m001-20210630 (attached as .config) > > compiler: gcc-9 (Debian 9.3.0-22) 9.3.0 > > > > If you fix the issue, kindly add following tag as appropriate > > Reported-by: kernel test robot > > Reported-by: Dan Carpenter > > > > New smatch warnings: > > drivers/gpu/drm/i915/gt/selftest_migrate.c:102 copy() error: uninitialized symbol 'rq'. > > drivers/gpu/drm/i915/gt/selftest_migrate.c:113 copy() error: uninitialized symbol 'vaddr'. > > > > Old smatch warnings: > > drivers/gpu/drm/i915/gem/i915_gem_object.h:182 __i915_gem_object_lock() error: we previously assumed 'ww' could be null (see line 171) > > > > vim +/rq +102 drivers/gpu/drm/i915/gt/selftest_migrate.c > > > > cf586021642d80 Chris Wilson 2021-06-17 32 static int copy(struct intel_migrate *migrate, > > cf586021642d80 Chris Wilson 2021-06-17 33 int (*fn)(struct intel_migrate *migrate, > > cf586021642d80 Chris Wilson 2021-06-17 34 struct i915_gem_ww_ctx *ww, > > cf586021642d80 Chris Wilson 2021-06-17 35 struct drm_i915_gem_object *src, > > cf586021642d80 Chris Wilson 2021-06-17 36 struct drm_i915_gem_object *dst, > > cf586021642d80 Chris Wilson 2021-06-17 37 struct i915_request **out), > > cf586021642d80 Chris Wilson 2021-06-17 38 u32 sz, struct rnd_state *prng) > > cf586021642d80 Chris Wilson 2021-06-17 39 { > > cf586021642d80 Chris Wilson 2021-06-17 40 struct drm_i915_private *i915 = migrate->context->engine->i915; > > cf586021642d80 Chris Wilson 2021-06-17 41 struct drm_i915_gem_object *src, *dst; > > cf586021642d80 Chris Wilson 2021-06-17 42 struct i915_request *rq; > > cf586021642d80 Chris Wilson 2021-06-17 43 struct i915_gem_ww_ctx ww; > > cf586021642d80 Chris Wilson 2021-06-17 44 u32 *vaddr; > > cf586021642d80 Chris Wilson 2021-06-17 45 int err = 0; > > > > One way to silence these warnings would be to initialize err = -EINVAL. > > Then Smatch would know that we goto err_out for an empty list. > > > > cf586021642d80 Chris Wilson 2021-06-17 46 int i; > > cf586021642d80 Chris Wilson 2021-06-17 47 > > cf586021642d80 Chris Wilson 2021-06-17 48 src = create_lmem_or_internal(i915, sz); > > cf586021642d80 Chris Wilson 2021-06-17 49 if (IS_ERR(src)) > > cf586021642d80 Chris Wilson 2021-06-17 50 return 0; > > cf586021642d80 Chris Wilson 2021-06-17 51 > > cf586021642d80 Chris Wilson 2021-06-17 52 dst = i915_gem_object_create_internal(i915, sz); > > cf586021642d80 Chris Wilson 2021-06-17 53 if (IS_ERR(dst)) > > cf586021642d80 Chris Wilson 2021-06-17 54 goto err_free_src; > > cf586021642d80 Chris Wilson 2021-06-17 55 > > cf586021642d80 Chris Wilson 2021-06-17 56 for_i915_gem_ww(&ww, err, true) { > > cf586021642d80 Chris Wilson 2021-06-17 57 err = i915_gem_object_lock(src, &ww); > > cf586021642d80 Chris Wilson 2021-06-17 58 if (err) > > cf586021642d80 Chris Wilson 2021-06-17 59 continue; > > cf586021642d80 Chris Wilson 2021-06-17 60 > > cf586021642d80 Chris Wilson 2021-06-17 61 err = i915_gem_object_lock(dst, &ww); > > cf586021642d80 Chris Wilson 2021-06-17 62 if (err) > > cf586021642d80 Chris Wilson 2021-06-17 63 continue; > > cf586021642d80 Chris Wilson 2021-06-17 64 > > cf586021642d80 Chris Wilson 2021-06-17 65 vaddr = i915_gem_object_pin_map(src, I915_MAP_WC); > > cf586021642d80 Chris Wilson 2021-06-17 66 if (IS_ERR(vaddr)) { > > cf586021642d80 Chris Wilson 2021-06-17 67 err = PTR_ERR(vaddr); > > cf586021642d80 Chris Wilson 2021-06-17 68 continue; > > cf586021642d80 Chris Wilson 2021-06-17 69 } > > cf586021642d80 Chris Wilson 2021-06-17 70 > > cf586021642d80 Chris Wilson 2021-06-17 71 for (i = 0; i < sz / sizeof(u32); i++) > > cf586021642d80 Chris Wilson 2021-06-17 72 vaddr[i] = i; > > cf586021642d80 Chris Wilson 2021-06-17 73 i915_gem_object_flush_map(src); > > cf586021642d80 Chris Wilson 2021-06-17 74 > > cf586021642d80 Chris Wilson 2021-06-17 75 vaddr = i915_gem_object_pin_map(dst, I915_MAP_WC); > > cf586021642d80 Chris Wilson 2021-06-17 76 if (IS_ERR(vaddr)) { > > cf586021642d80 Chris Wilson 2021-06-17 77 err = PTR_ERR(vaddr); > > cf586021642d80 Chris Wilson 2021-06-17 78 goto unpin_src; > > cf586021642d80 Chris Wilson 2021-06-17 79 } > > cf586021642d80 Chris Wilson 2021-06-17 80 > > cf586021642d80 Chris Wilson 2021-06-17 81 for (i = 0; i < sz / sizeof(u32); i++) > > cf586021642d80 Chris Wilson 2021-06-17 82 vaddr[i] = ~i; > > cf586021642d80 Chris Wilson 2021-06-17 83 i915_gem_object_flush_map(dst); > > cf586021642d80 Chris Wilson 2021-06-17 84 > > cf586021642d80 Chris Wilson 2021-06-17 85 err = fn(migrate, &ww, src, dst, &rq); > > cf586021642d80 Chris Wilson 2021-06-17 86 if (!err) > > cf586021642d80 Chris Wilson 2021-06-17 87 continue; > > > > Does fn() initialize "rq" on the success path? Anyway Smatch would > > complain anyway because it thinks the list could be empty or that we > > might hit and early continue for everything. > > The fn() will always first initialize the rq to NULL. If it returns > success then rq will always be a valid rq. If it returns an err then > the rq might be NULL, or a valid rq depending on how far the copy/fn > got. > > And for_i915_gem_ww() will always run at least once, since ww->loop = > true, so this looks like a false positive? You don't think i915_gem_object_lock(), i915_gem_object_pin_map() or i915_gem_object_pin_map() can fail? regards, dan carpenter