Re: [PATCH] Revised timerfd() interface

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



Hi Davide,

> > > > As I think about this more, I see more problems with
> > > > your argument.  timerfd needs the ability to get and 
> > > > get-while-setting just as much as the earlier APIs.
> > > > Consider a library that creates a timerfd file descriptor that
> > > > is handed off to an application: that library may want
> > > > to modify the timer settings without having to create a
> > > > new file descriptor (the app mey not be able to be told about
> > > > the new fd).  Your argument just doesn't hold, AFAICS.
> > > 
> > > Such hypotethical library, in case it really wanted to offer such 
> > > functionality, could simply return an handle instead of the raw fd,
> > > and take care of all that stuff in userspace.
> > 
> > Did I miss something?  Is it not the case that as soon as the
> > library returns a handle, rather than an fd, then the whole
> > advantage of timerfd() (being able to select/poll/epoll on 
> > the timer as well as other fds) is lost?  
> 
> Why? The handle would simply be a little struct where the timerfd fd is 
> stored, and a XXX_getfd() would return it.
> So my point is, I doubt such functionalities are really needed, and I 
> also argue that the kernel is the best place for such wrapper code
> to go.

So what happens if one thread (via the library) wants modify
a timer's settings at the same timer as another thread is 
select()ing on it?  The first thread can't do this by creating
a new timerfd timer, since it wants to affect the select()
in the other thread?

Cheers,

Michael
-- 
Michael Kerrisk
maintainer of Linux man pages Sections 2, 3, 4, 5, and 7 

Want to help with man page maintenance?  
Grab the latest tarball at
http://www.kernel.org/pub/linux/docs/manpages , 
read the HOWTOHELP file and grep the source 
files for 'FIXME'.

-
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/

[Index of Archives]     [Kernel Newbies]     [Netfilter]     [Bugtraq]     [Photo]     [Stuff]     [Gimp]     [Yosemite News]     [MIPS Linux]     [ARM Linux]     [Linux Security]     [Linux RAID]     [Video 4 Linux]     [Linux for the blind]     [Linux Resources]
  Powered by Linux