Commit d11c563d authored by Paul E. McKenney's avatar Paul E. McKenney Committed by Ingo Molnar

sched: Use lockdep-based checking on rcu_dereference()

Update the rcu_dereference() usages to take advantage of the new
lockdep-based checking.
Signed-off-by: default avatarPaul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: laijs@cn.fujitsu.com
Cc: dipankar@in.ibm.com
Cc: mathieu.desnoyers@polymtl.ca
Cc: josh@joshtriplett.org
Cc: dvhltc@us.ibm.com
Cc: niv@us.ibm.com
Cc: peterz@infradead.org
Cc: rostedt@goodmis.org
Cc: Valdis.Kletnieks@vt.edu
Cc: dhowells@redhat.com
LKML-Reference: <1266887105-1528-6-git-send-email-paulmck@linux.vnet.ibm.com>
[ -v2: fix allmodconfig missing symbol export build failure on x86 ]
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent a898def2
......@@ -28,6 +28,7 @@ struct css_id;
extern int cgroup_init_early(void);
extern int cgroup_init(void);
extern void cgroup_lock(void);
extern int cgroup_lock_is_held(void);
extern bool cgroup_lock_live_group(struct cgroup *cgrp);
extern void cgroup_unlock(void);
extern void cgroup_fork(struct task_struct *p);
......@@ -486,7 +487,9 @@ static inline struct cgroup_subsys_state *cgroup_subsys_state(
static inline struct cgroup_subsys_state *task_subsys_state(
struct task_struct *task, int subsys_id)
{
return rcu_dereference(task->cgroups->subsys[subsys_id]);
return rcu_dereference_check(task->cgroups->subsys[subsys_id],
rcu_read_lock_held() ||
cgroup_lock_is_held());
}
static inline struct cgroup* task_cgroup(struct task_struct *task,
......
......@@ -280,7 +280,7 @@ static inline void put_cred(const struct cred *_cred)
* task or by holding tasklist_lock to prevent it from being unlinked.
*/
#define __task_cred(task) \
((const struct cred *)(rcu_dereference((task)->real_cred)))
((const struct cred *)(rcu_dereference_check((task)->real_cred, rcu_read_lock_held() || lockdep_is_held(&tasklist_lock))))
/**
* get_task_cred - Get another task's objective credentials
......
......@@ -416,7 +416,9 @@ static noinline void __init_refok rest_init(void)
kernel_thread(kernel_init, NULL, CLONE_FS | CLONE_SIGHAND);
numa_default_policy();
pid = kernel_thread(kthreadd, NULL, CLONE_FS | CLONE_FILES);
rcu_read_lock();
kthreadd_task = find_task_by_pid_ns(pid, &init_pid_ns);
rcu_read_unlock();
unlock_kernel();
/*
......
......@@ -166,6 +166,20 @@ static DEFINE_SPINLOCK(hierarchy_id_lock);
*/
static int need_forkexit_callback __read_mostly;
#ifdef CONFIG_PROVE_LOCKING
int cgroup_lock_is_held(void)
{
return lockdep_is_held(&cgroup_mutex);
}
#else /* #ifdef CONFIG_PROVE_LOCKING */
int cgroup_lock_is_held(void)
{
return mutex_is_locked(&cgroup_mutex);
}
#endif /* #else #ifdef CONFIG_PROVE_LOCKING */
EXPORT_SYMBOL_GPL(cgroup_lock_is_held);
/* convenient tests for these bits */
inline int cgroup_is_removed(const struct cgroup *cgrp)
{
......
......@@ -85,7 +85,9 @@ static void __exit_signal(struct task_struct *tsk)
BUG_ON(!sig);
BUG_ON(!atomic_read(&sig->count));
sighand = rcu_dereference(tsk->sighand);
sighand = rcu_dereference_check(tsk->sighand,
rcu_read_lock_held() ||
lockdep_is_held(&tasklist_lock));
spin_lock(&sighand->siglock);
posix_cpu_timers_exit(tsk);
......@@ -170,8 +172,10 @@ void release_task(struct task_struct * p)
repeat:
tracehook_prepare_release_task(p);
/* don't need to get the RCU readlock here - the process is dead and
* can't be modifying its own credentials */
* can't be modifying its own credentials. But shut RCU-lockdep up */
rcu_read_lock();
atomic_dec(&__task_cred(p)->user->processes);
rcu_read_unlock();
proc_flush_task(p);
......@@ -473,9 +477,11 @@ static void close_files(struct files_struct * files)
/*
* It is safe to dereference the fd table without RCU or
* ->file_lock because this is the last reference to the
* files structure.
* files structure. But use RCU to shut RCU-lockdep up.
*/
rcu_read_lock();
fdt = files_fdtable(files);
rcu_read_unlock();
for (;;) {
unsigned long set;
i = j * __NFDBITS;
......@@ -521,10 +527,12 @@ void put_files_struct(struct files_struct *files)
* at the end of the RCU grace period. Otherwise,
* you can free files immediately.
*/
rcu_read_lock();
fdt = files_fdtable(files);
if (fdt != &files->fdtab)
kmem_cache_free(files_cachep, files);
free_fdtable(fdt);
rcu_read_unlock();
}
}
......
......@@ -86,6 +86,7 @@ int max_threads; /* tunable limit on nr_threads */
DEFINE_PER_CPU(unsigned long, process_counts) = 0;
__cacheline_aligned DEFINE_RWLOCK(tasklist_lock); /* outer */
EXPORT_SYMBOL_GPL(tasklist_lock);
int nr_processes(void)
{
......
......@@ -78,10 +78,10 @@ static int __kprobes notifier_call_chain(struct notifier_block **nl,
int ret = NOTIFY_DONE;
struct notifier_block *nb, *next_nb;
nb = rcu_dereference(*nl);
nb = rcu_dereference_raw(*nl);
while (nb && nr_to_call) {
next_nb = rcu_dereference(nb->next);
next_nb = rcu_dereference_raw(nb->next);
#ifdef CONFIG_DEBUG_NOTIFIERS
if (unlikely(!func_ptr_is_kernel_text(nb->notifier_call))) {
......@@ -309,7 +309,7 @@ int __blocking_notifier_call_chain(struct blocking_notifier_head *nh,
* racy then it does not matter what the result of the test
* is, we re-check the list after having taken the lock anyway:
*/
if (rcu_dereference(nh->head)) {
if (rcu_dereference_raw(nh->head)) {
down_read(&nh->rwsem);
ret = notifier_call_chain(&nh->head, val, v, nr_to_call,
nr_calls);
......
......@@ -367,7 +367,7 @@ struct task_struct *pid_task(struct pid *pid, enum pid_type type)
struct task_struct *result = NULL;
if (pid) {
struct hlist_node *first;
first = rcu_dereference(pid->tasks[type].first);
first = rcu_dereference_check(pid->tasks[type].first, rcu_read_lock_held() || lockdep_is_held(&tasklist_lock));
if (first)
result = hlist_entry(first, struct task_struct, pids[(type)].node);
}
......
......@@ -645,6 +645,11 @@ static inline int cpu_of(struct rq *rq)
#endif
}
#define for_each_domain_rd(p) \
rcu_dereference_check((p), \
rcu_read_lock_sched_held() || \
lockdep_is_held(&sched_domains_mutex))
/*
* The domain tree (rq->sd) is protected by RCU's quiescent state transition.
* See detach_destroy_domains: synchronize_sched for details.
......@@ -653,7 +658,7 @@ static inline int cpu_of(struct rq *rq)
* preempt-disabled sections.
*/
#define for_each_domain(cpu, __sd) \
for (__sd = rcu_dereference(cpu_rq(cpu)->sd); __sd; __sd = __sd->parent)
for (__sd = for_each_domain_rd(cpu_rq(cpu)->sd); __sd; __sd = __sd->parent)
#define cpu_rq(cpu) (&per_cpu(runqueues, (cpu)))
#define this_rq() (&__get_cpu_var(runqueues))
......@@ -1531,7 +1536,7 @@ static unsigned long target_load(int cpu, int type)
static struct sched_group *group_of(int cpu)
{
struct sched_domain *sd = rcu_dereference(cpu_rq(cpu)->sd);
struct sched_domain *sd = rcu_dereference_sched(cpu_rq(cpu)->sd);
if (!sd)
return NULL;
......@@ -4888,7 +4893,7 @@ static void run_rebalance_domains(struct softirq_action *h)
static inline int on_null_domain(int cpu)
{
return !rcu_dereference(cpu_rq(cpu)->sd);
return !rcu_dereference_sched(cpu_rq(cpu)->sd);
}
/*
......
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