From: James Morse james.morse@arm.com
The rdt_enable_key is switched when resctrl is mounted, and used to prevent a second mount of the filesystem. It also enables the architecture's context switch code.
This requires another architecture to have the same set of static-keys, as resctrl depends on them too. The existing users of these static-keys are implicitly also checking if the filesystem is mounted.
Make the resctrl_mounted checks explicit: resctrl can keep track of whether it has been mounted once. This doesn't need to be combined with whether the arch code is context switching the CLOSID.
rdt_mon_enable_key is never used just to test that resctrl is mounted, but does also have this implication. Add a resctrl_mounted to all uses of rdt_mon_enable_key.
This will allow the static-key changing to be moved behind resctrl_arch_ calls.
Signed-off-by: James Morse james.morse@arm.com Tested-by: Shaopeng Tan tan.shaopeng@fujitsu.com Tested-by: Peter Newman peternewman@google.com Tested-by: Babu Moger babu.moger@amd.com Reviewed-by: Shaopeng Tan tan.shaopeng@fujitsu.com Reviewed-by: Reinette Chatre reinette.chatre@intel.com Reviewed-by: Babu Moger babu.moger@amd.com --- arch/x86/kernel/cpu/resctrl/internal.h | 1 + arch/x86/kernel/cpu/resctrl/monitor.c | 12 ++++++++++-- arch/x86/kernel/cpu/resctrl/rdtgroup.c | 23 +++++++++++++++++------ 3 files changed, 28 insertions(+), 8 deletions(-)
diff --git a/arch/x86/kernel/cpu/resctrl/internal.h b/arch/x86/kernel/cpu/resctrl/internal.h index bb07b9b01e36..5ce49503fcd8 100644 --- a/arch/x86/kernel/cpu/resctrl/internal.h +++ b/arch/x86/kernel/cpu/resctrl/internal.h @@ -145,6 +145,7 @@ extern bool rdt_alloc_capable; extern bool rdt_mon_capable; extern unsigned int rdt_mon_features; extern struct list_head resctrl_schema_all; +extern bool resctrl_mounted;
enum rdt_group_type { RDTCTRL_GROUP = 0, diff --git a/arch/x86/kernel/cpu/resctrl/monitor.c b/arch/x86/kernel/cpu/resctrl/monitor.c index 20fe7ed494c2..e3e42736fb22 100644 --- a/arch/x86/kernel/cpu/resctrl/monitor.c +++ b/arch/x86/kernel/cpu/resctrl/monitor.c @@ -835,7 +835,11 @@ void mbm_handle_overflow(struct work_struct *work)
mutex_lock(&rdtgroup_mutex);
- if (!static_branch_likely(&rdt_mon_enable_key)) + /* + * If the filesystem has been unmounted this work no longer needs to + * run. + */ + if (!resctrl_mounted || !static_branch_likely(&rdt_mon_enable_key)) goto out_unlock;
r = &rdt_resources_all[RDT_RESOURCE_L3].r_resctrl; @@ -868,7 +872,11 @@ void mbm_setup_overflow_handler(struct rdt_domain *dom, unsigned long delay_ms) unsigned long delay = msecs_to_jiffies(delay_ms); int cpu;
- if (!static_branch_likely(&rdt_mon_enable_key)) + /* + * When a domain comes online there is no guarantee the filesystem is + * mounted. If not, there is no need to catch counter overflow. + */ + if (!resctrl_mounted || !static_branch_likely(&rdt_mon_enable_key)) return; cpu = cpumask_any_housekeeping(&dom->cpu_mask); dom->mbm_work_cpu = cpu; diff --git a/arch/x86/kernel/cpu/resctrl/rdtgroup.c b/arch/x86/kernel/cpu/resctrl/rdtgroup.c index 460ac501f9e8..646d224c3ac9 100644 --- a/arch/x86/kernel/cpu/resctrl/rdtgroup.c +++ b/arch/x86/kernel/cpu/resctrl/rdtgroup.c @@ -42,6 +42,9 @@ LIST_HEAD(rdt_all_groups); /* list of entries for the schemata file */ LIST_HEAD(resctrl_schema_all);
+/* The filesystem can only be mounted once. */ +bool resctrl_mounted; + /* Kernel fs node for "info" directory under root */ static struct kernfs_node *kn_info;
@@ -881,7 +884,7 @@ int proc_resctrl_show(struct seq_file *s, struct pid_namespace *ns, mutex_lock(&rdtgroup_mutex);
/* Return empty if resctrl has not been mounted. */ - if (!static_branch_unlikely(&rdt_enable_key)) { + if (!resctrl_mounted) { seq_puts(s, "res:\nmon:\n"); goto unlock; } @@ -2613,7 +2616,7 @@ static int rdt_get_tree(struct fs_context *fc) /* * resctrl file system can only be mounted once. */ - if (static_branch_unlikely(&rdt_enable_key)) { + if (resctrl_mounted) { ret = -EBUSY; goto out; } @@ -2674,8 +2677,10 @@ static int rdt_get_tree(struct fs_context *fc) if (rdt_mon_capable) static_branch_enable_cpuslocked(&rdt_mon_enable_key);
- if (rdt_alloc_capable || rdt_mon_capable) + if (rdt_alloc_capable || rdt_mon_capable) { static_branch_enable_cpuslocked(&rdt_enable_key); + resctrl_mounted = true; + }
if (is_mbm_enabled()) { r = &rdt_resources_all[RDT_RESOURCE_L3].r_resctrl; @@ -2949,6 +2954,7 @@ static void rdt_kill_sb(struct super_block *sb) static_branch_disable_cpuslocked(&rdt_alloc_enable_key); static_branch_disable_cpuslocked(&rdt_mon_enable_key); static_branch_disable_cpuslocked(&rdt_enable_key); + resctrl_mounted = false; kernfs_kill_sb(sb); mutex_unlock(&rdtgroup_mutex); cpus_read_unlock(); @@ -3918,7 +3924,7 @@ void resctrl_offline_domain(struct rdt_resource *r, struct rdt_domain *d) * If resctrl is mounted, remove all the * per domain monitor data directories. */ - if (static_branch_unlikely(&rdt_mon_enable_key)) + if (resctrl_mounted && static_branch_unlikely(&rdt_mon_enable_key)) rmdir_mondata_subdir_allrdtgrp(r, d->id);
if (is_mbm_enabled()) @@ -3995,8 +4001,13 @@ int resctrl_online_domain(struct rdt_resource *r, struct rdt_domain *d) if (is_llc_occupancy_enabled()) INIT_DELAYED_WORK(&d->cqm_limbo, cqm_handle_limbo);
- /* If resctrl is mounted, add per domain monitor data directories. */ - if (static_branch_unlikely(&rdt_mon_enable_key)) + /* + * If the filesystem is not mounted then only the default resource group + * exists. Creation of its directories is deferred until mount time + * by rdt_get_tree() calling mkdir_mondata_all(). + * If resctrl is mounted, add per domain monitor data directories. + */ + if (resctrl_mounted && static_branch_unlikely(&rdt_mon_enable_key)) mkdir_mondata_subdir_allrdtgrp(r, d);
return 0;