diff options
Diffstat (limited to 'kernel/cgroup/rstat.c')
| -rw-r--r-- | kernel/cgroup/rstat.c | 25 |
1 files changed, 16 insertions, 9 deletions
diff --git a/kernel/cgroup/rstat.c b/kernel/cgroup/rstat.c index ce4752ab9e09..cbeaa499a96a 100644 --- a/kernel/cgroup/rstat.c +++ b/kernel/cgroup/rstat.c @@ -47,8 +47,20 @@ static spinlock_t *ss_rstat_lock(struct cgroup_subsys *ss) static raw_spinlock_t *ss_rstat_cpu_lock(struct cgroup_subsys *ss, int cpu) { - if (ss) + if (ss) { + /* + * Depending on config, the subsystem per-cpu lock type may be an + * empty struct. In enviromnents where this is the case, allocation + * of this field is not performed in ss_rstat_init(). Avoid a + * cpu-based offset relative to NULL by returning early. When the + * lock type is zero in size, the corresponding lock functions are + * no-ops so passing them NULL is acceptable. + */ + if (sizeof(*ss->rstat_ss_cpu_lock) == 0) + return NULL; + return per_cpu_ptr(ss->rstat_ss_cpu_lock, cpu); + } return per_cpu_ptr(&rstat_base_cpu_lock, cpu); } @@ -510,20 +522,15 @@ int __init ss_rstat_init(struct cgroup_subsys *ss) { int cpu; -#ifdef CONFIG_SMP /* - * On uniprocessor machines, arch_spinlock_t is defined as an empty - * struct. Avoid allocating a size of zero by having this block - * excluded in this case. It's acceptable to leave the subsystem locks - * unitialized since the associated lock functions are no-ops in the - * non-smp case. + * Depending on config, the subsystem per-cpu lock type may be an empty + * struct. Avoid allocating a size of zero in this case. */ - if (ss) { + if (ss && sizeof(*ss->rstat_ss_cpu_lock)) { ss->rstat_ss_cpu_lock = alloc_percpu(raw_spinlock_t); if (!ss->rstat_ss_cpu_lock) return -ENOMEM; } -#endif spin_lock_init(ss_rstat_lock(ss)); for_each_possible_cpu(cpu) |