Messages in this thread | | | Date | Thu, 21 Feb 2013 14:30:26 +0400 | From | Pavel Emelyanov <> | Subject | Re: [PATCH] ptrace: add ability to retrieve signals without removing them from a queue |
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On 02/21/2013 02:37 AM, Oleg Nesterov wrote: > On 02/19, Pavel Emelyanov wrote: >> >> On 02/19/2013 11:34 PM, Oleg Nesterov wrote: >>> But, given that every PEEK does list_for_each() until it finds the >>> necessary sequence number, I am wondering how this O(n**2) will work >>> if you want to dump 126065 signals ;) >> >> Isn't it the great reason for making the addr point to a structure, that >> would look like >> >> struct siginfo_peek_arg { >> unsigned flags; /* all bits but 0th, that selects between private/shared >> queues, should be zero */ >> unsigned int off; /* from which siginfo to start */ >> unsigned int nr; /* how may siginfos to take */ >> }; > > I am fine either way, to me everything looks better than signalfd > hacks. > > But if you meant "avoid n^2", this won't help? You can't do > copy_siginfo_to_user() under ->siglock, so you need to restart > list_for_each() anyway.
Or allocate intermediate buffer putting the siginfo's there.
> Oleg.
Thanks, Pavel
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