proc: make /proc/self point to thread
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| # | Subject and files | Size | Replies | Applied |
|---|---|---|---|---|
| 1/1 | proc: make /proc/self point to threadfs/ | +7 | 4 replies |
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Cover letter [PATCH 0/1] proc: make /proc/self point to thread
Quoted 4 lines · Linus Torvalds
Quoted 1 line · Linus Torvalds
Quoted 8 lines
Quoted 3 lines
Patch looks ok to me, but since this has never worked and nobody has actually complained, I can't really convince myself that this is critical.
Actually, let's back-track..
Did you try the other approach? Make
/proc/selfpoint to the thread instead of the task?
Yes, I thought about this. But I agree with Eric, we probably need another magic link, /proc/thread or whatever.
And. I think that s/task_pid/task_tgid/ in proc_fd_permission() makes sense anyway. It is not only for /proc/self, why we should restrict the access to /proc/<sub-thread>/fd ?
Quoted 4 lines
The thread-group leader seems to have these extra files:
- autogroup,
coredump_filter, mountstats, net, task
Note really afaics. Yes, tgid_base_stuff and tid_base_stuff differ, but proc_root_lookup() uses tgid_base_stuff in any case, so /proc/<tid>/ also has task,mountstats,etc even if it is not leader.
Quoted 1 line
Yes, it would be semantically different,
And I am afraid this can break things. But I leave this to you and Eric.
Personally I think that /proc/self pointing to "current" is better, and in fact I was surprised when I recently found that this is not true. But perhaps it is too late to change this old behaviour.
Quoted 4 lines
but it would mean that
"/proc/self/fd/" would actually make sense in a way that it currently does *not* - which would seem fairly important, since the primary use for it tends to be/dev/stdin.
I think this doesn't matter "in practice", normally all threads have the same ->files. Who needs CLONE_THREAD without CLONE_FILES ?
Quoted 2 lines
And the other semantic differences might be much harder to notice. Worth testing?
Perhaps... Well, if Andrew takes this patch (assuming you and Eric ack it), we can see if we have any bug reports.
Oleg.