On Tue, 03 Feb 2009 16:22:02 -0600 Matt Mackall <mpm@xxxxxxxxxxx> wrote: > But that re-opens the question of what to do about poor Jon's quest. > > I got confused halfway through as he went from using a global fasync > spinlock to a non-locked but atomic flag bit. Not sure why using a > per-file or per-inode lock doesn't work for the fasync code. No per-file lock because (1) there is resistance to growing struct file, and (2) lockless algorithms are all the rage now. Additionally, solving the fasync-atomicity problem with locks requires the use of a mutex (or the BKL) rather than a spinlock. I suppose we could combine a global f_flags lock with the set-FASYNC-in-fasync_helper() bits. At this point Poor Jon sees a fork in the road as he contemplates the future of his quest: - Go with this patch set, perhaps with a bit of cleanup as suggested by Andrew. - Go back to the global lock. - Go away, leave the BKL in place, and wait for somebody smarter to attack the problem. Any wise guidance would be most welcome... jon -- To unsubscribe from this list: send the line "unsubscribe linux-api" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
