From 8053bdd5ce15dcf043d41a4dd6cac4a5567effdc Mon Sep 17 00:00:00 2001 From: Oleg Nesterov Date: Wed, 17 Jun 2009 16:27:34 -0700 Subject: [PATCH] ptrace_get_task_struct: s/tasklist/rcu/, make it static - Use rcu_read_lock() instead of tasklist_lock to find/get the task in ptrace_get_task_struct(). - Make it static, it has no callers outside of ptrace.c. - The comment doesn't match the reality, this helper does not do any checks. Beacuse it is really trivial and static I removed the whole comment. Signed-off-by: Oleg Nesterov Acked-by: Roland McGrath Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/ptrace.h | 1 - kernel/ptrace.c | 16 +++------------- 2 files changed, 3 insertions(+), 14 deletions(-) diff --git a/include/linux/ptrace.h b/include/linux/ptrace.h index 59e133d39d50..7456d7d87a19 100644 --- a/include/linux/ptrace.h +++ b/include/linux/ptrace.h @@ -81,7 +81,6 @@ extern long arch_ptrace(struct task_struct *child, long request, long addr, long data); -extern struct task_struct *ptrace_get_task_struct(pid_t pid); extern int ptrace_traceme(void); extern int ptrace_readdata(struct task_struct *tsk, unsigned long src, char __user *dst, int len); extern int ptrace_writedata(struct task_struct *tsk, char __user *src, unsigned long dst, int len); diff --git a/kernel/ptrace.c b/kernel/ptrace.c index 38fdfea1a15a..a64fe75a48ba 100644 --- a/kernel/ptrace.c +++ b/kernel/ptrace.c @@ -581,26 +581,16 @@ int ptrace_request(struct task_struct *child, long request, return ret; } -/** - * ptrace_get_task_struct -- grab a task struct reference for ptrace - * @pid: process id to grab a task_struct reference of - * - * This function is a helper for ptrace implementations. It checks - * permissions and then grabs a task struct for use of the actual - * ptrace implementation. - * - * Returns the task_struct for @pid or an ERR_PTR() on failure. - */ -struct task_struct *ptrace_get_task_struct(pid_t pid) +static struct task_struct *ptrace_get_task_struct(pid_t pid) { struct task_struct *child; - read_lock(&tasklist_lock); + rcu_read_lock(); child = find_task_by_vpid(pid); if (child) get_task_struct(child); + rcu_read_unlock(); - read_unlock(&tasklist_lock); if (!child) return ERR_PTR(-ESRCH); return child; -- 2.20.1