Re: RFC [patch 13/34] PID Virtualization Define new task_pid api

[ebiederm@xmission.com (Eric W. Biederman)]

Hubertus Franke <frankeh@watson.ibm.com> writes:

> Eric W. Biederman wrote:
>> Hubertus Franke <frankeh@watson.ibm.com> writes:
>> Any place the kernel saves a pid and then proceeds to signal it later.
>> At that later point in time it is possibly you will be in the wrong
>> context.
>>
>
> Yes, that's possible.. In the current patch that is not a problem, because
> the internal pid (aka kpid) == <vpid,containerid>  mangeled together.
> So in those cases, the kernel would have to keep <pid, container_id>

Agreed, and for the internal implementation I think having them mangled
together make sense, so long as we never export that form to userspace.

>> This probably justifies having a kpid_t that has both the process
>> space id and the pid in it.  For when the kernel is storing pids to
>> use as weak references, for signal purposes etc.
>>
>
> An that's what the current patch does. Only thing is we did not rename
> everything to kpid_t!

Yep. But because of that you couldn't detect mixing of pid and kpid.

>> At least tty_io.c and fcntl.c have examples where you the caller
>> may not have the proper context.
>
> Can you point those out directly .. thanks..

Short version.  tty's send signals on hangup and f_setown can trigger signals
being sent.

Eric



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