On 10/16/2017 09:24 AM, Oleg Nesterov wrote:
On 10/13, Konstantin Khlebnikov wrote:
On 13.10.2017 19:05, Oleg Nesterov wrote:
I won't insist, but this suggests we should add a new helper,
get_ns_by_fd_type(fd, type), and convert get_net_ns_by_fd() to use it
as well.
That was in v3.
I'll prefer to this later, separately. And replace fget with fdget which
allows to do this without atomic operations if task is single-threaded.
OK, agreed,
Stupid question. Can't we make a simpler API which doesn't need /proc/ ?
I mean,
sys_translate_pid(pid_t pid, pid_t source_pid, pid_t target_pid)
{
struct pid_namespace *source_ns, *target_ns;
source_ns = task_active_pid_ns(find_task_by_vpid(source_pid));
target_ns = task_active_pid_ns(find_task_by_vpid(target_pid));
...
}
Yes, this is more limited... Do you have a use-case when this is not enough?
That was in v1 but considered too racy.
Hmm, I don't understand...
Yes sure, this is racy but open("/proc/$pid/ns/pid") is racy too?
OK, once you do fd=open("/proc/$pid/ns/pid") you can use this fd even after
its owner exits, while find_task_by_vpid() will fail or find another task if
this pid was already reused.
But once again, do you have a use-case when this is important?
I believe that in V1 Eric pointed out that pid in general is not a clean
way to represent
namespace. (https://lkml.org/lkml/2015/9/22/1087) Few old interfaces
used pid only because at that time there was no better way to represent
namespaces.
But we could merge both ways:
source >= 0 - pidns fs
source < 0 - task_pid = -source
But for what? I must have missed something...
Oleg.
--
To unsubscribe from this list: send the line "unsubscribe linux-api" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
