diff options
Diffstat (limited to 'include/linux/cpuset.h')
| -rw-r--r-- | include/linux/cpuset.h | 31 |
1 files changed, 23 insertions, 8 deletions
diff --git a/include/linux/cpuset.h b/include/linux/cpuset.h index 119a3f9604b0..a1e6a33a4b03 100644 --- a/include/linux/cpuset.h +++ b/include/linux/cpuset.h @@ -18,31 +18,42 @@ #ifdef CONFIG_CPUSETS +/* + * Static branch rewrites can happen in an arbitrary order for a given + * key. In code paths where we need to loop with read_mems_allowed_begin() and + * read_mems_allowed_retry() to get a consistent view of mems_allowed, we need + * to ensure that begin() always gets rewritten before retry() in the + * disabled -> enabled transition. If not, then if local irqs are disabled + * around the loop, we can deadlock since retry() would always be + * comparing the latest value of the mems_allowed seqcount against 0 as + * begin() still would see cpusets_enabled() as false. The enabled -> disabled + * transition should happen in reverse order for the same reasons (want to stop + * looking at real value of mems_allowed.sequence in retry() first). + */ +extern struct static_key_false cpusets_pre_enable_key; extern struct static_key_false cpusets_enabled_key; static inline bool cpusets_enabled(void) { return static_branch_unlikely(&cpusets_enabled_key); } -static inline int nr_cpusets(void) -{ - /* jump label reference count + the top-level cpuset */ - return static_key_count(&cpusets_enabled_key.key) + 1; -} - static inline void cpuset_inc(void) { + static_branch_inc(&cpusets_pre_enable_key); static_branch_inc(&cpusets_enabled_key); } static inline void cpuset_dec(void) { static_branch_dec(&cpusets_enabled_key); + static_branch_dec(&cpusets_pre_enable_key); } extern int cpuset_init(void); extern void cpuset_init_smp(void); +extern void cpuset_force_rebuild(void); extern void cpuset_update_active_cpus(void); +extern void cpuset_wait_for_hotplug(void); extern void cpuset_cpus_allowed(struct task_struct *p, struct cpumask *mask); extern void cpuset_cpus_allowed_fallback(struct task_struct *p); extern nodemask_t cpuset_mems_allowed(struct task_struct *p); @@ -115,7 +126,7 @@ extern void cpuset_print_current_mems_allowed(void); */ static inline unsigned int read_mems_allowed_begin(void) { - if (!cpusets_enabled()) + if (!static_branch_unlikely(&cpusets_pre_enable_key)) return 0; return read_seqcount_begin(¤t->mems_allowed_seq); @@ -129,7 +140,7 @@ static inline unsigned int read_mems_allowed_begin(void) */ static inline bool read_mems_allowed_retry(unsigned int seq) { - if (!cpusets_enabled()) + if (!static_branch_unlikely(&cpusets_enabled_key)) return false; return read_seqcount_retry(¤t->mems_allowed_seq, seq); @@ -155,11 +166,15 @@ static inline bool cpusets_enabled(void) { return false; } static inline int cpuset_init(void) { return 0; } static inline void cpuset_init_smp(void) {} +static inline void cpuset_force_rebuild(void) { } + static inline void cpuset_update_active_cpus(void) { partition_sched_domains(1, NULL, NULL); } +static inline void cpuset_wait_for_hotplug(void) { } + static inline void cpuset_cpus_allowed(struct task_struct *p, struct cpumask *mask) { |