If potentially no valid element is found, 'pstate' would contain an invalid pointer past the iterator loop. To ensure 'pstate' is always valid, we only set it if the correct element was found. That allows adding a BUG_ON in case the code works incorrectly, exposing currently undetectable potential bugs. Additionally, Linus proposed to avoid any use of the list iterator variable after the loop, in the attempt to move the list iterator variable declaration into the marcro to avoid any potential misuse after the loop [1]. Link: https://lore.kernel.org/all/CAHk-=wgRr_D8CB-D9Kg-c=EHreAsk5SqXPwr9Y7k9sA6cWXJ6w@xxxxxxxxxxxxxx/ [1] Signed-off-by: Jakob Koschel <jkl820.git@xxxxxxxxx> --- drivers/gpu/drm/nouveau/nvkm/subdev/clk/base.c | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-) diff --git a/drivers/gpu/drm/nouveau/nvkm/subdev/clk/base.c b/drivers/gpu/drm/nouveau/nvkm/subdev/clk/base.c index da07a2fbef06..871127dfe1d7 100644 --- a/drivers/gpu/drm/nouveau/nvkm/subdev/clk/base.c +++ b/drivers/gpu/drm/nouveau/nvkm/subdev/clk/base.c @@ -269,14 +269,17 @@ nvkm_pstate_prog(struct nvkm_clk *clk, int pstatei) struct nvkm_subdev *subdev = &clk->subdev; struct nvkm_fb *fb = subdev->device->fb; struct nvkm_pci *pci = subdev->device->pci; - struct nvkm_pstate *pstate; + struct nvkm_pstate *pstate = NULL, *iter; int ret, idx = 0; - list_for_each_entry(pstate, &clk->states, head) { - if (idx++ == pstatei) + list_for_each_entry(iter, &clk->states, head) { + if (idx++ == pstatei) { + pstate = iter; break; + } } + BUG_ON(!pstate); nvkm_debug(subdev, "setting performance state %d\n", pstatei); clk->pstate = pstatei; -- 2.34.1
