diff options
| author | Paul E. McKenney <paulmck@linux.vnet.ibm.com> | 2010-03-03 07:46:56 -0800 |
|---|---|---|
| committer | Ingo Molnar <mingo@elte.hu> | 2010-03-04 11:46:14 +0100 |
| commit | db1466b3e1bd1727375cdbfcbea4bcce2f860f61 (patch) | |
| tree | e56e8d7b82f8851e570d95f531ec62e4d107967a | |
| parent | 0e064caf6402d1d67db4233d26beec88ca212919 (diff) | |
rcu: Use wrapper function instead of exporting tasklist_lock
Lockdep-RCU commit d11c563d exported tasklist_lock, which is not
a good thing. This patch instead exports a function that uses
lockdep to check whether tasklist_lock is held.
Suggested-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Paul 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
Cc: Christoph Hellwig <hch@lst.de>
LKML-Reference: <1267631219-8713-1-git-send-email-paulmck@linux.vnet.ibm.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
| -rw-r--r-- | include/linux/cred.h | 2 | ||||
| -rw-r--r-- | include/linux/sched.h | 4 | ||||
| -rw-r--r-- | kernel/exit.c | 2 | ||||
| -rw-r--r-- | kernel/fork.c | 9 | ||||
| -rw-r--r-- | kernel/pid.c | 4 |
5 files changed, 17 insertions, 4 deletions
diff --git a/include/linux/cred.h b/include/linux/cred.h index 4db09f89b63..52507c3e138 100644 --- a/include/linux/cred.h +++ b/include/linux/cred.h @@ -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_check((task)->real_cred, rcu_read_lock_held() || lockdep_is_held(&tasklist_lock)))) + ((const struct cred *)(rcu_dereference_check((task)->real_cred, rcu_read_lock_held() || lockdep_tasklist_lock_is_held()))) /** * get_task_cred - Get another task's objective credentials diff --git a/include/linux/sched.h b/include/linux/sched.h index 0eef87b58ea..a47af2064dc 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -258,6 +258,10 @@ extern spinlock_t mmlist_lock; struct task_struct; +#ifdef CONFIG_PROVE_RCU +extern int lockdep_tasklist_lock_is_held(void); +#endif /* #ifdef CONFIG_PROVE_RCU */ + extern void sched_init(void); extern void sched_init_smp(void); extern asmlinkage void schedule_tail(struct task_struct *prev); diff --git a/kernel/exit.c b/kernel/exit.c index 45ed043b8bf..fed3a4db6f0 100644 --- a/kernel/exit.c +++ b/kernel/exit.c @@ -87,7 +87,7 @@ static void __exit_signal(struct task_struct *tsk) sighand = rcu_dereference_check(tsk->sighand, rcu_read_lock_held() || - lockdep_is_held(&tasklist_lock)); + lockdep_tasklist_lock_is_held()); spin_lock(&sighand->siglock); posix_cpu_timers_exit(tsk); diff --git a/kernel/fork.c b/kernel/fork.c index 17bbf093356..8691c540a47 100644 --- a/kernel/fork.c +++ b/kernel/fork.c @@ -86,7 +86,14 @@ 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); + +#ifdef CONFIG_PROVE_RCU +int lockdep_tasklist_lock_is_held(void) +{ + return lockdep_is_held(&tasklist_lock); +} +EXPORT_SYMBOL_GPL(lockdep_tasklist_lock_is_held); +#endif /* #ifdef CONFIG_PROVE_RCU */ int nr_processes(void) { diff --git a/kernel/pid.c b/kernel/pid.c index b08e697cd83..b6064405f36 100644 --- a/kernel/pid.c +++ b/kernel/pid.c @@ -367,7 +367,9 @@ 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_check(pid->tasks[type].first, rcu_read_lock_held() || lockdep_is_held(&tasklist_lock)); + first = rcu_dereference_check(pid->tasks[type].first, + rcu_read_lock_held() || + lockdep_tasklist_lock_is_held()); if (first) result = hlist_entry(first, struct task_struct, pids[(type)].node); } |