diff options
Diffstat (limited to 'arch/x86/kernel/cpu/resctrl/core.c')
| -rw-r--r-- | arch/x86/kernel/cpu/resctrl/core.c | 44 |
1 files changed, 34 insertions, 10 deletions
diff --git a/arch/x86/kernel/cpu/resctrl/core.c b/arch/x86/kernel/cpu/resctrl/core.c index b03a6c658ae5..8a4ef4f5bddc 100644 --- a/arch/x86/kernel/cpu/resctrl/core.c +++ b/arch/x86/kernel/cpu/resctrl/core.c @@ -16,6 +16,7 @@ #define pr_fmt(fmt) "resctrl: " fmt +#include <linux/cpu.h> #include <linux/slab.h> #include <linux/err.h> #include <linux/cacheinfo.h> @@ -25,8 +26,15 @@ #include <asm/resctrl.h> #include "internal.h" -/* Mutex to protect rdtgroup access. */ -DEFINE_MUTEX(rdtgroup_mutex); +/* + * rdt_domain structures are kfree()d when their last CPU goes offline, + * and allocated when the first CPU in a new domain comes online. + * The rdt_resource's domain list is updated when this happens. Readers of + * the domain list must either take cpus_read_lock(), or rely on an RCU + * read-side critical section, to avoid observing concurrent modification. + * All writers take this mutex: + */ +static DEFINE_MUTEX(domain_list_lock); /* * The cached resctrl_pqr_state is strictly per CPU and can never be @@ -354,6 +362,15 @@ struct rdt_domain *get_domain_from_cpu(int cpu, struct rdt_resource *r) { struct rdt_domain *d; + /* + * Walking r->domains, ensure it can't race with cpuhp. + * Because this is called via IPI by rdt_ctrl_update(), assertions + * about locks this thread holds will lead to false positives. Check + * someone is holding the CPUs lock. + */ + if (IS_ENABLED(CONFIG_HOTPLUG_CPU) && IS_ENABLED(CONFIG_LOCKDEP)) + WARN_ON_ONCE(!lockdep_is_cpus_held()); + list_for_each_entry(d, &r->domains, list) { /* Find the domain that contains this CPU */ if (cpumask_test_cpu(cpu, &d->cpu_mask)) @@ -510,6 +527,8 @@ static void domain_add_cpu(int cpu, struct rdt_resource *r) struct rdt_domain *d; int err; + lockdep_assert_held(&domain_list_lock); + d = rdt_find_domain(r, id, &add_pos); if (IS_ERR(d)) { pr_warn("Couldn't find cache id for CPU %d\n", cpu); @@ -543,11 +562,12 @@ static void domain_add_cpu(int cpu, struct rdt_resource *r) return; } - list_add_tail(&d->list, add_pos); + list_add_tail_rcu(&d->list, add_pos); err = resctrl_online_domain(r, d); if (err) { - list_del(&d->list); + list_del_rcu(&d->list); + synchronize_rcu(); domain_free(hw_dom); } } @@ -558,6 +578,8 @@ static void domain_remove_cpu(int cpu, struct rdt_resource *r) struct rdt_hw_domain *hw_dom; struct rdt_domain *d; + lockdep_assert_held(&domain_list_lock); + d = rdt_find_domain(r, id, NULL); if (IS_ERR_OR_NULL(d)) { pr_warn("Couldn't find cache id for CPU %d\n", cpu); @@ -568,7 +590,8 @@ static void domain_remove_cpu(int cpu, struct rdt_resource *r) cpumask_clear_cpu(cpu, &d->cpu_mask); if (cpumask_empty(&d->cpu_mask)) { resctrl_offline_domain(r, d); - list_del(&d->list); + list_del_rcu(&d->list); + synchronize_rcu(); /* * rdt_domain "d" is going to be freed below, so clear @@ -598,13 +621,13 @@ static int resctrl_arch_online_cpu(unsigned int cpu) { struct rdt_resource *r; - mutex_lock(&rdtgroup_mutex); + mutex_lock(&domain_list_lock); for_each_capable_rdt_resource(r) domain_add_cpu(cpu, r); - clear_closid_rmid(cpu); + mutex_unlock(&domain_list_lock); + clear_closid_rmid(cpu); resctrl_online_cpu(cpu); - mutex_unlock(&rdtgroup_mutex); return 0; } @@ -613,13 +636,14 @@ static int resctrl_arch_offline_cpu(unsigned int cpu) { struct rdt_resource *r; - mutex_lock(&rdtgroup_mutex); resctrl_offline_cpu(cpu); + mutex_lock(&domain_list_lock); for_each_capable_rdt_resource(r) domain_remove_cpu(cpu, r); + mutex_unlock(&domain_list_lock); + clear_closid_rmid(cpu); - mutex_unlock(&rdtgroup_mutex); return 0; } |