On Sat, Jan 12, 2013 at 08:27:06AM +0800, David Xu wrote: > On 2013/01/12 07:29, Jilles Tjoelker wrote: > > On Fri, Jan 11, 2013 at 10:49:38PM +0200, Konstantin Belousov wrote: > >> http://people.freebsd.org/~kib/misc/rtld-sigblock.3.patch > > The new fields td_sigblock_ptr and td_sigblock_val are in the part that > > is zeroed for new threads, while the code in rtld appears to expect them > > to be copied (on fork, vfork and pthread_create). The fields are > > correctly zeroed on exec. > > > > Sharing the magic variable between threads means that one thread holding > > an rtld lock will block signals for all other threads as well. This is > > different from how the normal signal mask works but I don't know whether > > it may break things. However, the patch depends on it in some way > > because sigtd() does not know about fast sigblock and will therefore > > happily select a thread that is fast-sigblocking to handle a signal > > directed at the process. > > > > Although libthr's postpone approach is somewhat ugly, it does not depend > > on any non-standard kernel features and does not delay the default > > action. Would it be possible to move that code to libc to make things > > easier for rtld? It looks like this requires teaching libc about various > > threading concepts, though. > Long time ago, if i remembered correctly, kib said that he wanted to > merge libthr code into libc, I don't know its state. Yes, this is correct, and I still want this.
> > > Something feels ugly about not allowing applications to use this, > > although I don't know how it would work. On the other hand, the strange > > signal state created by this and implicit assumptions that the duration > > will be short may be a reason to restrict its use to a relatively small > > piece of code. > > > True, it seems it is for short duration.
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