On Wed, Aug 22, 2007 at 02:02:10PM +0400, Oleg Nesterov wrote: > On 08/22, Jarek Poplawski wrote: > > > > On 20-08-2007 18:01, Oleg Nesterov wrote: > > > do_sigaction() returns -ERESTARTNOINTR if signal_pending(). The comment > > > says: > > > > > > * If there might be a fatal signal pending on multiple > > > * threads, make sure we take it before changing the action. > > > > > > I think this is not needed. We should only worry about SIGNAL_GROUP_EXIT > > > case, > > > bit it implies a pending SIGKILL which can't be cleared by do_sigaction. > > > > Isn't it for optimization e.g., to skip this 'do while' loop below for > > such multiple threads, which would get SIGKILL or SIGSTOP anyway? > > Yes, in that case this 'do while' doesn't make sense. But this is very > unlikely, sigaction() shouldn't be called too much often, better to save > a couple of bytes from icache. > > Also, please note that sigaction() is not special, almost any system call > could be started with > > if (current->signal->flags & SIGNAL_GROUP_EXIT) > return ANYVALUE; > > to "optimize" for the case when the task is dying.
OK, I only wasn't sure this was considered before getting this "not needed" verdict. BTW, sometimes, even if something is very unlikely, but very time-consuming, and skipping this isn't so costly, there could be a gain at the end. So, maybe it's about individual cases and some testing too? (At least, it seems, somebody found this so usable, she/he bothered with such a long comment, and we know it's a last thing any decent kernel hacker would care to do...) Jarek P. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
