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| author | Lai Jiangshan <laijs@cn.fujitsu.com> | 2008-10-05 00:51:15 +0400 |
|---|---|---|
| committer | Alexey Dobriyan <adobriyan@gmail.com> | 2008-10-10 04:18:57 +0400 |
| commit | a6bebbc87a8c16eabb6bd5c6fd2d994be0236fba (patch) | |
| tree | 3e617ca49063f3a12c982da5d6c687882a1b4070 | |
| parent | 53167a3ef23df561d898dee636f3393e9fba937c (diff) | |
| download | op-kernel-dev-a6bebbc87a8c16eabb6bd5c6fd2d994be0236fba.zip op-kernel-dev-a6bebbc87a8c16eabb6bd5c6fd2d994be0236fba.tar.gz | |
[PATCH] signal, procfs: some lock_task_sighand() users do not need rcu_read_lock()
lock_task_sighand() make sure task->sighand is being protected,
so we do not need rcu_read_lock().
[ exec() will get task->sighand->siglock before change task->sighand! ]
But code using rcu_read_lock() _just_ to protect lock_task_sighand()
only appear in procfs. (and some code in procfs use lock_task_sighand()
without such redundant protection.)
Other subsystem may put lock_task_sighand() into rcu_read_lock()
critical region, but these rcu_read_lock() are used for protecting
"for_each_process()", "find_task_by_vpid()" etc. , not for protecting
lock_task_sighand().
Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
[ok from Oleg]
Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
| -rw-r--r-- | fs/proc/array.c | 2 | ||||
| -rw-r--r-- | fs/proc/base.c | 9 | ||||
| -rw-r--r-- | kernel/sched_debug.c | 2 |
3 files changed, 1 insertions, 12 deletions
diff --git a/fs/proc/array.c b/fs/proc/array.c index 71c9be5..1c8d7b5 100644 --- a/fs/proc/array.c +++ b/fs/proc/array.c @@ -261,7 +261,6 @@ static inline void task_sig(struct seq_file *m, struct task_struct *p) sigemptyset(&ignored); sigemptyset(&caught); - rcu_read_lock(); if (lock_task_sighand(p, &flags)) { pending = p->pending.signal; shpending = p->signal->shared_pending.signal; @@ -272,7 +271,6 @@ static inline void task_sig(struct seq_file *m, struct task_struct *p) qlim = p->signal->rlim[RLIMIT_SIGPENDING].rlim_cur; unlock_task_sighand(p, &flags); } - rcu_read_unlock(); seq_printf(m, "Threads:\t%d\n", num_threads); seq_printf(m, "SigQ:\t%lu/%lu\n", qsize, qlim); diff --git a/fs/proc/base.c b/fs/proc/base.c index a28840b..bb63fa1 100644 --- a/fs/proc/base.c +++ b/fs/proc/base.c @@ -164,7 +164,6 @@ static struct fs_struct *get_fs_struct(struct task_struct *task) static int get_nr_threads(struct task_struct *tsk) { - /* Must be called with the rcu_read_lock held */ unsigned long flags; int count = 0; @@ -471,14 +470,10 @@ static int proc_pid_limits(struct task_struct *task, char *buffer) struct rlimit rlim[RLIM_NLIMITS]; - rcu_read_lock(); - if (!lock_task_sighand(task,&flags)) { - rcu_read_unlock(); + if (!lock_task_sighand(task, &flags)) return 0; - } memcpy(rlim, task->signal->rlim, sizeof(struct rlimit) * RLIM_NLIMITS); unlock_task_sighand(task, &flags); - rcu_read_unlock(); /* * print the file header @@ -3088,9 +3083,7 @@ static int proc_task_getattr(struct vfsmount *mnt, struct dentry *dentry, struct generic_fillattr(inode, stat); if (p) { - rcu_read_lock(); stat->nlink += get_nr_threads(p); - rcu_read_unlock(); put_task_struct(p); } diff --git a/kernel/sched_debug.c b/kernel/sched_debug.c index bbe6b31..ad958c1 100644 --- a/kernel/sched_debug.c +++ b/kernel/sched_debug.c @@ -333,12 +333,10 @@ void proc_sched_show_task(struct task_struct *p, struct seq_file *m) unsigned long flags; int num_threads = 1; - rcu_read_lock(); if (lock_task_sighand(p, &flags)) { num_threads = atomic_read(&p->signal->count); unlock_task_sighand(p, &flags); } - rcu_read_unlock(); SEQ_printf(m, "%s (%d, #threads: %d)\n", p->comm, p->pid, num_threads); SEQ_printf(m, |
