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authorLai Jiangshan <laijs@cn.fujitsu.com>2008-10-05 00:51:15 +0400
committerAlexey Dobriyan <adobriyan@gmail.com>2008-10-10 04:18:57 +0400
commita6bebbc87a8c16eabb6bd5c6fd2d994be0236fba (patch)
tree3e617ca49063f3a12c982da5d6c687882a1b4070 /kernel
parent53167a3ef23df561d898dee636f3393e9fba937c (diff)
downloadop-kernel-dev-a6bebbc87a8c16eabb6bd5c6fd2d994be0236fba.zip
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[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>
Diffstat (limited to 'kernel')
-rw-r--r--kernel/sched_debug.c2
1 files changed, 0 insertions, 2 deletions
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,
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