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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 <oleg@redhat.com>
Acked-by: Roland McGrath <roland@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Oleg Nesterov 2009-06-17 16:27:34 -07:00 committed by Linus Torvalds
parent 4b105cbbaf
commit 8053bdd5ce
2 changed files with 3 additions and 14 deletions
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1
include/linux/ptrace.h
View File

@ -81,7 +81,6 @@
extern long arch_ptrace(struct task_struct *child, long request, long addr, long data); 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_traceme(void);
extern int ptrace_readdata(struct task_struct *tsk, unsigned long src, char __user *dst, int len); 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); extern int ptrace_writedata(struct task_struct *tsk, char __user *src, unsigned long dst, int len);

16
kernel/ptrace.c
View File

@ -581,26 +581,16 @@ int ptrace_request(struct task_struct *child, long request,
return ret; return ret;
} }
/** static struct task_struct *ptrace_get_task_struct(pid_t pid)
* 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)
{ {
struct task_struct *child; struct task_struct *child;
read_lock(&tasklist_lock); rcu_read_lock();
child = find_task_by_vpid(pid); child = find_task_by_vpid(pid);
if (child) if (child)
get_task_struct(child); get_task_struct(child);
rcu_read_unlock();
read_unlock(&tasklist_lock);
if (!child) if (!child)
return ERR_PTR(-ESRCH); return ERR_PTR(-ESRCH);
return child; return child;