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They are meaningful only for >> resctrl_kcfg.k_rdtgrp. >> >> On groups that do not own the kernel-mode binding, they appear as inactive >> stubs and can let user space inspect or update state that does not apply to >> that group. >> >> Hide kmode_cpus and kmode_cpus_list on groups that are not bound to >> kernel-mode. Keep the files hidden when groups are created, show them when >> rdtgroup_config_kmode() binds the group, and hide them again when the >> binding is released. >> >> Signed-off-by: Babu Moger >> --- >> v4: Updated the changelog and code comments. >> >> v3: New patch to hide/show "kmode_cpus" and "kmode_cpus_list" when kernel >> modes binding changes. >> --- >> fs/resctrl/rdtgroup.c | 33 +++++++++++++++++++++++++++++++++ >> 1 file changed, 33 insertions(+) >> >> diff --git a/fs/resctrl/rdtgroup.c b/fs/resctrl/rdtgroup.c >> index 413d3ff14546..c537846d9264 100644 >> --- a/fs/resctrl/rdtgroup.c >> +++ b/fs/resctrl/rdtgroup.c >> @@ -1127,6 +1127,35 @@ static int resctrl_kernel_mode_show(struct kernfs_open_file *of, >> return ret; >> } >> >> +/** >> + * resctrl_kmode_files_set_visible() - Toggle visibility of the per-group >> + * kernel-mode CPU files under @rdtgrp. >> + * @rdtgrp: Resctrl group whose "kmode_cpus" / "kmode_cpus_list" files >> + * should be hidden or shown. >> + * @visible: %true to expose the files, %false to hide them via >> + * kernfs_show(). >> + * >> + * Each file is resolved independently as a sibling under @rdtgrp->kn. >> + * Failures from kernfs_find_and_get() are deliberately ignored, allowing >> + * callers to invoke this before activation, during group creation, or when >> + * the kernel-mode binding is updated. >> + */ >> +static void resctrl_kmode_files_set_visible(struct rdtgroup *rdtgrp, bool visible) >> +{ >> + /* Keep in sync with res_common_files[] entries for these files. */ >> + static const char * const files[] = { "kmode_cpus", "kmode_cpus_list" }; >> + struct kernfs_node *kn; >> + int i; >> + >> + for (i = 0; i < ARRAY_SIZE(files); i++) { >> + kn = kernfs_find_and_get(rdtgrp->kn, files[i]); >> + if (!kn) >> + continue; >> + kernfs_show(kn, visible); >> + kernfs_put(kn); >> + } >> +} >> + >> /** >> * rdtgroup_config_kmode_reset() - Tear down the kernel-mode binding on @rdtgrp >> * @rdtgrp: Resctrl group whose kernel-mode binding is being released. >> @@ -1155,6 +1184,7 @@ static void rdtgroup_config_kmode_reset(struct rdtgroup *rdtgrp, >> >> out_clear: >> cpumask_clear(&rdtgrp->kmode_cpu_mask); >> + resctrl_kmode_files_set_visible(rdtgrp, false); >> rdtgrp->kmode = false; >> } >> >> @@ -3068,6 +3098,7 @@ static int rdt_get_tree(struct fs_context *fc) >> if (ret) >> goto out_closid_exit; >> >> + resctrl_kmode_files_set_visible(&rdtgroup_default, false); >> kernfs_activate(rdtgroup_default.kn); >> >> ret = rdtgroup_create_info_dir(rdtgroup_default.kn); >> @@ -4098,6 +4129,7 @@ static int rdtgroup_mkdir_mon(struct kernfs_node *parent_kn, >> goto out_unlock; >> } >> >> + resctrl_kmode_files_set_visible(rdtgrp, false); >> kernfs_activate(rdtgrp->kn); >> >> /* >> @@ -4142,6 +4174,7 @@ static int rdtgroup_mkdir_ctrl_mon(struct kernfs_node *parent_kn, >> if (ret) >> goto out_closid_free; >> >> + resctrl_kmode_files_set_visible(rdtgrp, false); >> kernfs_activate(rdtgrp->kn); >> >> ret = rdtgroup_init_alloc(rdtgrp); > > Sprinkling these resctrl_kmode_files_set_visible() in every path that creates these files > seem error prone. Could this be simplified with a new, for example, rftype::create_hidden that > will instruct the file to be created hidden. This would just create the file correctly from the > beginning and eliminate these calls that go back and "fix things up" for kernel mode use. This may > also eliminate the need to ignore errors in resctrl_kmode_files_set_visible() making this > more robust while making it obvious how the file visibility is actually connected to the > kernel mode since that would be the only points where the file visibility is changed. > Already discussed to create the hidden files for all the groups during the group creation. Then call resctrl_kmode_files_set_visible() based on visibility requirement when group is added/removed from global kernel mode. https://lore.kernel.org/lkml/98568620-7e61-4d43-b72c-5866a7d3bca1@intel.com/. Thanks Babu