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Commit 8053bdd5 authored by Oleg Nesterov's avatar Oleg Nesterov Committed by Linus Torvalds
Browse files

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: default avatarOleg Nesterov <oleg@redhat.com>
Acked-by: default avatarRoland McGrath <roland@redhat.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 4b105cbb

include/linux/ptrace.h

+0 −1
Original line number Diff line number Diff line
@@ -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);

kernel/ptrace.c

+3 −13
Original line number Diff line number Diff line
@@ -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;