09.12.2021 22:32, Nicolin Chen пишет: > On Thu, Dec 09, 2021 at 05:47:18PM +0300, Dmitry Osipenko wrote: >> External email: Use caution opening links or attachments >> >> >> 09.12.2021 10:38, Nicolin Chen пишет: >>> @@ -545,6 +719,15 @@ static void tegra_smmu_detach_as(struct tegra_smmu *smmu, >>> if (group->swgrp != swgrp) >>> continue; >>> group->as = NULL; >>> + >>> + if (smmu->debugfs_mappings) { >> Do we really need this check? >> >> Looks like all debugfs_create_dir() usages in this driver are incorrect, >> that function never returns NULL. Please fix this. > debugfs_create_dir returns ERR_PTR on failure. So here should be > to check !IS_ERR. Thanks for pointing it out! > All debugfs functions handle IS_ERR(). GregKH removes all such checks all over the kernel. So the check shouldn't be needed at all, please remove it if it's unneeded or prove that it's needed.