cgroup: Remove CFTYPE_PRESSURE

CFTYPE_PRESSURE is used to flag PSI related files so that they are not
created if PSI is disabled during boot. It's a bit weird to use a generic
flag to mark a specific file type. Let's instead move the PSI files into its
own cftypes array and add/rm them conditionally. This is a bit more code but
cleaner.

No userland visible changes.

Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>

diff --git a/include/linux/cgroup-defs.h b/include/linux/cgroup-defs.h
index 9fa1652..8f481d1 100644 (file)
--- a/include/linux/cgroup-defs.h
+++ b/include/linux/cgroup-defs.h
@@ -126,7 +126,6 @@ enum {
        CFTYPE_NO_PREFIX        = (1 << 3),     /* (DON'T USE FOR NEW FILES) no subsys prefix */
        CFTYPE_WORLD_WRITABLE   = (1 << 4),     /* (DON'T USE FOR NEW FILES) S_IWUGO */
        CFTYPE_DEBUG            = (1 << 5),     /* create when cgroup_debug */
-       CFTYPE_PRESSURE         = (1 << 6),     /* only if pressure feature is enabled */
 
        /* internal flags, do not use outside cgroup core proper */
        __CFTYPE_ONLY_ON_DFL    = (1 << 16),    /* only on default hierarchy */

diff --git a/kernel/cgroup/cgroup.c b/kernel/cgroup/cgroup.c
index bd9fe6e..e240158 100644 (file)
--- a/kernel/cgroup/cgroup.c
+++ b/kernel/cgroup/cgroup.c
@@ -217,6 +217,7 @@ struct cgroup_namespace init_cgroup_ns = {
 
 static struct file_system_type cgroup2_fs_type;
 static struct cftype cgroup_base_files[];
+static struct cftype cgroup_psi_files[];
 
 /* cgroup optional features */
 enum cgroup_opt_features {
@@ -1689,12 +1690,16 @@ static void css_clear_dir(struct cgroup_subsys_state *css)
        css->flags &= ~CSS_VISIBLE;
 
        if (!css->ss) {
-               if (cgroup_on_dfl(cgrp))
-                       cfts = cgroup_base_files;
-               else
-                       cfts = cgroup1_base_files;
-
-               cgroup_addrm_files(css, cgrp, cfts, false);
+               if (cgroup_on_dfl(cgrp)) {
+                       cgroup_addrm_files(css, cgrp,
+                                          cgroup_base_files, false);
+                       if (cgroup_psi_enabled())
+                               cgroup_addrm_files(css, cgrp,
+                                                  cgroup_psi_files, false);
+               } else {
+                       cgroup_addrm_files(css, cgrp,
+                                          cgroup1_base_files, false);
+               }
        } else {
                list_for_each_entry(cfts, &css->ss->cfts, node)
                        cgroup_addrm_files(css, cgrp, cfts, false);
@@ -1717,14 +1722,22 @@ static int css_populate_dir(struct cgroup_subsys_state *css)
                return 0;
 
        if (!css->ss) {
-               if (cgroup_on_dfl(cgrp))
-                       cfts = cgroup_base_files;
-               else
-                       cfts = cgroup1_base_files;
-
-               ret = cgroup_addrm_files(&cgrp->self, cgrp, cfts, true);
-               if (ret < 0)
-                       return ret;
+               if (cgroup_on_dfl(cgrp)) {
+                       ret = cgroup_addrm_files(&cgrp->self, cgrp,
+                                                cgroup_base_files, true);
+                       if (ret < 0)
+                               return ret;
+
+                       if (cgroup_psi_enabled()) {
+                               ret = cgroup_addrm_files(&cgrp->self, cgrp,
+                                                        cgroup_psi_files, true);
+                               if (ret < 0)
+                                       return ret;
+                       }
+               } else {
+                       cgroup_addrm_files(css, cgrp,
+                                          cgroup1_base_files, true);
+               }
        } else {
                list_for_each_entry(cfts, &css->ss->cfts, node) {
                        ret = cgroup_addrm_files(css, cgrp, cfts, true);
@@ -4132,8 +4145,6 @@ static int cgroup_addrm_files(struct cgroup_subsys_state *css,
 restart:
        for (cft = cfts; cft != cft_end && cft->name[0] != '\0'; cft++) {
                /* does cft->flags tell us to skip this file on @cgrp? */
-               if ((cft->flags & CFTYPE_PRESSURE) && !cgroup_psi_enabled())
-                       continue;
                if ((cft->flags & __CFTYPE_ONLY_ON_DFL) && !cgroup_on_dfl(cgrp))
                        continue;
                if ((cft->flags & __CFTYPE_NOT_ON_DFL) && cgroup_on_dfl(cgrp))
@@ -4218,9 +4229,6 @@ static int cgroup_init_cftypes(struct cgroup_subsys *ss, struct cftype *cfts)
                        break;
                }
 
-               if ((cft->flags & CFTYPE_PRESSURE) && !cgroup_psi_enabled())
-                       continue;
-
                if (cft->seq_start)
                        kf_ops = &cgroup_kf_ops;
                else
@@ -5144,10 +5152,13 @@ static struct cftype cgroup_base_files[] = {
                .name = "cpu.stat",
                .seq_show = cpu_stat_show,
        },
+       { }     /* terminate */
+};
+
+static struct cftype cgroup_psi_files[] = {
 #ifdef CONFIG_PSI
        {
                .name = "io.pressure",
-               .flags = CFTYPE_PRESSURE,
                .seq_show = cgroup_io_pressure_show,
                .write = cgroup_io_pressure_write,
                .poll = cgroup_pressure_poll,
@@ -5155,7 +5166,6 @@ static struct cftype cgroup_base_files[] = {
        },
        {
                .name = "memory.pressure",
-               .flags = CFTYPE_PRESSURE,
                .seq_show = cgroup_memory_pressure_show,
                .write = cgroup_memory_pressure_write,
                .poll = cgroup_pressure_poll,
@@ -5163,7 +5173,6 @@ static struct cftype cgroup_base_files[] = {
        },
        {
                .name = "cpu.pressure",
-               .flags = CFTYPE_PRESSURE,
                .seq_show = cgroup_cpu_pressure_show,
                .write = cgroup_cpu_pressure_write,
                .poll = cgroup_pressure_poll,
@@ -5930,6 +5939,7 @@ int __init cgroup_init(void)
 
        BUILD_BUG_ON(CGROUP_SUBSYS_COUNT > 16);
        BUG_ON(cgroup_init_cftypes(NULL, cgroup_base_files));
+       BUG_ON(cgroup_init_cftypes(NULL, cgroup_psi_files));
        BUG_ON(cgroup_init_cftypes(NULL, cgroup1_base_files));
 
        cgroup_rstat_boot();
@@ -6821,9 +6831,6 @@ static ssize_t show_delegatable_files(struct cftype *files, char *buf,
                if (!(cft->flags & CFTYPE_NS_DELEGATABLE))
                        continue;
 
-               if ((cft->flags & CFTYPE_PRESSURE) && !cgroup_psi_enabled())
-                       continue;
-
                if (prefix)
                        ret += snprintf(buf + ret, size - ret, "%s.", prefix);
 
@@ -6843,8 +6850,11 @@ static ssize_t delegate_show(struct kobject *kobj, struct kobj_attribute *attr,
        int ssid;
        ssize_t ret = 0;
 
-       ret = show_delegatable_files(cgroup_base_files, buf, PAGE_SIZE - ret,
-                                    NULL);
+       ret = show_delegatable_files(cgroup_base_files, buf + ret,
+                                    PAGE_SIZE - ret, NULL);
+       if (cgroup_psi_enabled())
+               ret += show_delegatable_files(cgroup_psi_files, buf + ret,
+                                             PAGE_SIZE - ret, NULL);
 
        for_each_subsys(ss, ssid)
                ret += show_delegatable_files(ss->dfl_cftypes, buf + ret,