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

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

include/linux/cgroup.h

+4 −1
Original line number Diff line number Diff line
@@ -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,

include/linux/cred.h

+1 −1
Original line number Diff line number Diff line
@@ -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

init/main.c

+2 −0
Original line number Diff line number Diff line
@@ -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();



	/*

kernel/cgroup.c

+14 −0
Original line number Diff line number Diff line
@@ -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)

{

kernel/exit.c

+11 −3
Original line number Diff line number Diff line
@@ -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();

	}

}