On 09/24, Konstantin Khlebnikov wrote:
On Thu, Sep 24, 2015 at 5:56 PM, Oleg Nesterov [off-list ref] wrote:
quoted
On 09/24, Konstantin Khlebnikov wrote:
quoted
+SYSCALL_DEFINE3(getvpid, pid_t, pid, int, source, int, target)
+{
+ struct file *source_file = NULL, *target_file = NULL;
+ struct pid_namespace *source_ns, *target_ns;
+ struct pid *struct_pid;
+ struct ns_common *ns;
+ pid_t result;
+
+ if (source >= 0) {
+ source_file = proc_ns_fget(source);
+ result = PTR_ERR(source_file);
+ if (IS_ERR(source_file))
+ goto out;
+ ns = get_proc_ns(file_inode(source_file));
+ result = -EINVAL;
+ if (ns->ops->type != CLONE_NEWPID)
+ goto out;
+ source_ns = container_of(ns, struct pid_namespace, ns);
+ } else
+ source_ns = task_active_pid_ns(current);
+
+ if (target >= 0) {
+ target_file = proc_ns_fget(target);
+ result = PTR_ERR(target_file);
+ if (IS_ERR(target_file))
+ goto out;
+ ns = get_proc_ns(file_inode(target_file));
+ result = -EINVAL;
+ if (ns->ops->type != CLONE_NEWPID)
+ goto out;
+ target_ns = container_of(ns, struct pid_namespace, ns);
+ } else
+ target_ns = task_active_pid_ns(current);
+
Hmm. Eric, Konstantin, how about (uncompiled/untested) patch below
in a preparation? The code above doesn't look very readable.
I've tried to do something like that but that comes too far so send patch as is.
OK, I won't insist.
The code above asks for cleanup/factorization, but we can do this
later.
Actually we can go deeper and replace struct file* with struct fd: this saves
couple atomic ops for singlethreaded task.
it's not about performance...
But yes, we can do more and create get_pid_ns_by_fd() similar to
get_net_ns_by_fd(). We do not need file at all, we need pid_ns.
Oleg.