2013/1/21 Andrew Vagin <avagin@xxxxxxxxxxxxx>: > On Sun, Jan 20, 2013 at 09:33:41PM +0100, Michael Kerrisk (man-pages) wrote: >> Hi Oleg, >> >> On Sun, Jan 20, 2013 at 8:55 PM, Oleg Nesterov <oleg@xxxxxxxxxx> wrote: >> > On 01/20, Andrew Vagin wrote: >> >> >> >> > SFD_RAW >> >> > SFD_SHARED_QUEUE -- reads will be from process-wide shared signal queue >> >> > SFD_PER_THREAD_QUEUE --reads will be from per-thread signal queue >> >> >> >> I suggested this variant in the initial series, but then we decided to >> >> avoid adding new flags. >> > >> > Yes, because SFD_SHARED/PRIVATE will add even more complications into this >> > code. And outside of signalfd.c too. And nobody except c/r will ever use >> > these features I guess. >> >> So, I must admit that I don't understand why adding SFD_SHARED and >> SFD_PER_THREAD in signalfd() makes things more complicated than adding >> the equivalents in pread(). But, I'll take your word for that, if >> that's what you meant. > > You could look at the initial series. > http://thread.gmane.org/gmane.linux.file-systems/70327 > > In this case dequeue_signal should be changed for specifying a queue. > signalfd_poll() should be fixed too. All this changes are not a big > deal, but... > > If we want to have two flags for specifying queues, we will need one > more flag SFD_PEEK, which will say, that signals should not be dequeued. > Currently we get this information from offset too. If offset isn't zero, > signals are not dequeued. With flags this sentence will look ugly. I'm going to prepare a series with flags tomorrow. Thanks. > >> >> However, note that I did suggest that in the initial implementation >> you might require that if SFD_SHARED_QUEUE or SFD_PER_THREAD_QUEUE is >> specified in signalfd(), then SFD_RAW could be required as well. >> Later, if someone wants to do the work, they could relax the >> constraint, so as to allow signalfd() to be used to do per-queue >> select even when reading siginfo (i.e., SFD_SHARED_QUEUE or >> SFD_PER_THREAD_QUEUE specified but not SFD_RAW). Surely that is not >> more complicated than the current implementation. And it allows for an >> orthogonal expansion of the design that seems more natural and may one >> day be useful. >> >> Cheers, >> >> Michael -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
