[PATCH v7 5/8] x86/resctrl: Unwind the errors inside rdt_enable_ctx()

From: Babu Moger
Date: Fri Aug 11 2023 - 16:10:42 EST


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.

Suggested-by: Reinette Chatre <reinette.chatre@xxxxxxxxx>
Signed-off-by: Babu Moger <babu.moger@xxxxxxx>
---
arch/x86/kernel/cpu/resctrl/rdtgroup.c | 44 ++++++++++++++++++++++++--------
1 file changed, 33 insertions(+), 11 deletions(-)

diff --git a/arch/x86/kernel/cpu/resctrl/rdtgroup.c b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
index 3010e3a1394d..0805fac04401 100644
--- a/arch/x86/kernel/cpu/resctrl/rdtgroup.c
+++ b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
@@ -2377,19 +2377,44 @@ static int mkdir_mondata_all(struct kernfs_node *parent_kn,
struct rdtgroup *prgrp,
struct kernfs_node **mon_data_kn);

+static void rdt_disable_ctx(struct rdt_fs_context *ctx)
+{
+ if (ctx->enable_cdpl2)
+ resctrl_arch_set_cdp_enabled(RDT_RESOURCE_L2, false);
+
+ if (ctx->enable_cdpl3)
+ resctrl_arch_set_cdp_enabled(RDT_RESOURCE_L3, false);
+
+ if (ctx->enable_mba_mbps)
+ 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_disable;
+ }

- if (!ret && ctx->enable_cdpl3)
+ if (ctx->enable_cdpl3) {
ret = resctrl_arch_set_cdp_enabled(RDT_RESOURCE_L3, true);
+ if (ret)
+ goto out_disable;
+ }

- if (!ret && ctx->enable_mba_mbps)
+ if (ctx->enable_mba_mbps) {
ret = set_mba_sc(true);
+ if (ret)
+ goto out_disable;
+ }
+
+ return 0;

+out_disable:
+ rdt_disable_ctx(ctx);
return ret;
}

@@ -2497,13 +2522,13 @@ 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();
@@ -2562,11 +2587,8 @@ static int rdt_get_tree(struct fs_context *fc)
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(ctx);
out:
rdt_last_cmd_clear();
mutex_unlock(&rdtgroup_mutex);