x86/resctrl: Unwind properly from rdt_enable_ctx()

rdt_enable_ctx() enables the features provided during resctrl mount.

Additions to rdt_enable_ctx() are required to also modify error paths
of rdt_enable_ctx() callers to ensure correct unwinding if errors
are encountered after calling rdt_enable_ctx(). This is error prone.

Introduce rdt_disable_ctx() to refactor the error unwinding of
rdt_enable_ctx() to simplify future additions. This also simplifies
cleanup in rdt_kill_sb().

Suggested-by: Reinette Chatre <reinette.chatre@intel.com>
Signed-off-by: Babu Moger <babu.moger@amd.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: Peter Newman <peternewman@google.com>
Reviewed-by: Tan Shaopeng <tan.shaopeng@jp.fujitsu.com>
Reviewed-by: Fenghua Yu <fenghua.yu@intel.com>
Reviewed-by: Reinette Chatre <reinette.chatre@intel.com>
Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Tested-by: Peter Newman <peternewman@google.com>
Tested-by: Tan Shaopeng <tan.shaopeng@jp.fujitsu.com>
Link: https://lore.kernel.org/r/20231017002308.134480-5-babu.moger@amd.com

diff --git a/arch/x86/kernel/cpu/resctrl/rdtgroup.c b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
index 125d12d8f4b9cef239724f68e32bee91a9df828b..d1b5fd70ccbb7dff8c0633eae89a8ebef29d62c9 100644 (file)
--- a/arch/x86/kernel/cpu/resctrl/rdtgroup.c
+++ b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
@@ -2308,14 +2308,6 @@ int resctrl_arch_set_cdp_enabled(enum resctrl_res_level l, bool enable)
        return 0;
 }
 
-static void cdp_disable_all(void)
-{
-       if (resctrl_arch_get_cdp_enabled(RDT_RESOURCE_L3))
-               resctrl_arch_set_cdp_enabled(RDT_RESOURCE_L3, false);
-       if (resctrl_arch_get_cdp_enabled(RDT_RESOURCE_L2))
-               resctrl_arch_set_cdp_enabled(RDT_RESOURCE_L2, false);
-}
-
 /*
  * We don't allow rdtgroup directories to be created anywhere
  * except the root directory. Thus when looking for the rdtgroup
@@ -2395,19 +2387,42 @@ static int mkdir_mondata_all(struct kernfs_node *parent_kn,
                             struct rdtgroup *prgrp,
                             struct kernfs_node **mon_data_kn);
 
+static void rdt_disable_ctx(void)
+{
+       resctrl_arch_set_cdp_enabled(RDT_RESOURCE_L3, false);
+       resctrl_arch_set_cdp_enabled(RDT_RESOURCE_L2, false);
+       set_mba_sc(false);
+}
+
 static int rdt_enable_ctx(struct rdt_fs_context *ctx)
 {
        int ret = 0;
 
-       if (ctx->enable_cdpl2)
+       if (ctx->enable_cdpl2) {
                ret = resctrl_arch_set_cdp_enabled(RDT_RESOURCE_L2, true);
+               if (ret)
+                       goto out_done;
+       }
 
-       if (!ret && ctx->enable_cdpl3)
+       if (ctx->enable_cdpl3) {
                ret = resctrl_arch_set_cdp_enabled(RDT_RESOURCE_L3, true);
+               if (ret)
+                       goto out_cdpl2;
+       }
 
-       if (!ret && ctx->enable_mba_mbps)
+       if (ctx->enable_mba_mbps) {
                ret = set_mba_sc(true);
+               if (ret)
+                       goto out_cdpl3;
+       }
+
+       return 0;
 
+out_cdpl3:
+       resctrl_arch_set_cdp_enabled(RDT_RESOURCE_L3, false);
+out_cdpl2:
+       resctrl_arch_set_cdp_enabled(RDT_RESOURCE_L2, false);
+out_done:
        return ret;
 }
 
@@ -2515,13 +2530,13 @@ static int rdt_get_tree(struct fs_context *fc)
        }
 
        ret = rdt_enable_ctx(ctx);
-       if (ret < 0)
-               goto out_cdp;
+       if (ret)
+               goto out;
 
        ret = schemata_list_create();
        if (ret) {
                schemata_list_destroy();
-               goto out_mba;
+               goto out_ctx;
        }
 
        closid_init();
@@ -2580,11 +2595,8 @@ out_info:
        kernfs_remove(kn_info);
 out_schemata_free:
        schemata_list_destroy();
-out_mba:
-       if (ctx->enable_mba_mbps)
-               set_mba_sc(false);
-out_cdp:
-       cdp_disable_all();
+out_ctx:
+       rdt_disable_ctx();
 out:
        rdt_last_cmd_clear();
        mutex_unlock(&rdtgroup_mutex);
@@ -2816,12 +2828,11 @@ static void rdt_kill_sb(struct super_block *sb)
        cpus_read_lock();
        mutex_lock(&rdtgroup_mutex);
 
-       set_mba_sc(false);
+       rdt_disable_ctx();
 
        /*Put everything back to default values. */
        for_each_alloc_capable_rdt_resource(r)
                reset_all_ctrls(r);
-       cdp_disable_all();
        rmdir_all_sub();
        rdt_pseudo_lock_release();
        rdtgroup_default.mode = RDT_MODE_SHAREABLE;