From a6bebbc87a8c16eabb6bd5c6fd2d994be0236fba Mon Sep 17 00:00:00 2001 From: Lai Jiangshan Date: Sun, 5 Oct 2008 00:51:15 +0400 Subject: [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 [ok from Oleg] Signed-off-by: Alexey Dobriyan --- fs/proc/base.c | 9 +-------- 1 file changed, 1 insertion(+), 8 deletions(-) (limited to 'fs/proc/base.c') diff --git a/fs/proc/base.c b/fs/proc/base.c index a28840b11b8..bb63fa1d34a 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); } -- cgit v1.2.3