On 05/15, Oleg Nesterov wrote:
On 05/15, Christian Brauner wrote:+SYSCALL_DEFINE2(pidfd_open, pid_t, pid, unsigned int, flags) +{ + int fd, ret; + struct pid *p; + struct task_struct *tsk; + + if (flags) + return -EINVAL; + + if (pid <= 0) + return -EINVAL; + + p = find_get_pid(pid); + if (!p) + return -ESRCH; + + rcu_read_lock(); + tsk = pid_task(p, PIDTYPE_PID);You do not need find_get_pid() before rcu_lock and put_pid() at the end. You can just do find_vpid() under rcu_read_lock().
Ah, sorry. Somehow I forgot you need to call pidfd_create(pid), you can't do this under rcu_read_lock(). So I was wrong, you can't avoid get/put_pid. Oleg.
