Messages in this thread | | | Date | Sat, 17 May 2008 10:11:37 -0700 (PDT) | From | Linus Torvalds <> | Subject | Re: [PATCH 3/3] posix timers: use SIGQUEUE_CANCELLED when the timer is destroyed |
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On Sat, 17 May 2008, Oleg Nesterov wrote:
> On 05/17, Oleg Nesterov wrote: > > > > This is a user visible change. With this patch sys_timer_delete() discards > > the pending signal which was generated by the timer. > > If this change is undesirable, we can (for example) do > > --- kernel/posix-timers.c > +++ kernel/posix-timers.c > @@ -885,6 +885,7 @@ itimer_delete(struct k_itimer *timer) > timer->it_process = NULL; > > unlock_timer(timer, flags); > + tmr->sigq->flags |= SIGQUEUE_CANCELLED; > release_posix_timer(timer, IT_ID_SET); > } > > instead, and still fix the "BUG 10460".
The only reason I like that better is that it makes me nervous when one re-initializes the whole flags field. So your original 3/3 patch
- q->flags &= ~SIGQUEUE_PREALLOC; + q->flags = SIGQUEUE_CANCELLED; /* clears SIGQUEUE_PREALLOC */
just makes me go "Hmm, what about all the other flag bits?"
Now, admittedly, there are currently (with your patch) just two SIGQUEUE_xyz bits, so by just doing that single assignment, you really only modify the two bits you want to modify. But maybe that will change. So I'd prefer to either write it as
q->flags &= ~SIGQUEUE_PREALLOC; q->flags |= SIGQUEUE_CANCELLED;
or to use bitfields, or to do something else to make it safe in the presense of multiple bits.
Your alternate patch obviously doesn't have that issue, since it just sets the single bit.
But apart from that issue, I have absolutely no preferences either way. You're effectively the maintainer in this area, you get to choose.
Linus
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