Messages in this thread |  | | | Date | Fri, 23 Mar 2012 14:34:04 +0100 | | From | Oleg Nesterov <> | | Subject | Re: [RFC 4/4] {RFC} kmod.c: Add new call_usermodehelper_timeout() API |
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On 03/22, Boaz Harrosh wrote: > > On 03/22/2012 07:27 AM, Oleg Nesterov wrote: > >> > >> usermodehelper: implement UMH_KILLABLE > >> > >> Implement UMH_KILLABLE, should be used along with UMH_WAIT_EXEC/PROC. The > >> caller must ensure that subprocess_info->path/etc can not go away until > >> call_usermodehelper_freeinfo(). > >> ... > >> > >> I think that my patch above does a much better/cleaner lifetime management of the > >> subprocess_info struct, with the use of a kref. > > > > This is subjective, you know ;) I specially tried to avoid the > > refcounting. > > > > Why? > > The all kref_ abstraction comes to a simple atomic_inc/dec.
Again, this is subjective, but kref_ looks like the unnecessary complication to me. But I won't insist, see below.
> > In any case. I do not know why do we need timeout, but this is > > orthogonal to KILLABLE. Please redo your patches on top of -mm > > tree? Please note that in this case the change becomes trivial. > > > > Yes you are right.
OK, good.
> > Hmm. For example, exit_mm() does xchg(). > > > > Again, Personally I like xchg, but not here, not for an object > life-time management. Two threads share a structure, that needs > to go when the last one ends.
And xchg(info->complete) implements the simplest counter, xchg() == NULL is equivalent to atomic_dec_and_test() == T.
But again, again, I won't argue if you send the patch which uses kref_ instead. I do not maintain this code and I do not really mind. And I never pretended my taste is good ;)
My point is, this is completely orthogonal to "add the timeout", and if you want to change the refcounting I'd suggest a separate patch.
What we need is wait_for_completion_state_timeout() to avoid the horror like
if (UMH_KILLABLE && !timeout) wait_for_completion_killable(...); else if (UMH_KILLABLE && timeout) wait_for_completion_killable_timeout(...); else if (!UMH_KILLABLE && !timeout) ... IOW, I think we need to export wait_for_common() first.
This is the only complication afaics. After that "add the timeout" becomes almost one-liner, with or without "switch to kref_".
> Is there an mm git tree?
No, afaik
> random linux-next/master point. Which should do the job.
Yes, I think this should work.
Oleg.
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