On 12/31, Linus Torvalds wrote: > > Oleg's patch to only wake up writers when readers have actually opened > up a slot may not make any actual difference (because readers in > *practice* always do big reads), Yes, yes, that patch is mostly cleanup/simplification. I'll write the changelog and send it after the holidays. Plus probably another one to fix the theoretical problem (I need to recheck) in wakeup_pipe_readers/writers. But let me ask another question right now. what do you think about another minor change below? Again, mostly to make this logic more understandable. Although I am not sure I really understand it... Oleg. diff --git a/fs/pipe.c b/fs/pipe.c index 82fede0f2111..ac3e7584726a 100644 --- a/fs/pipe.c +++ b/fs/pipe.c @@ -661,8 +661,11 @@ pipe_poll(struct file *filp, poll_table *wait) struct pipe_inode_info *pipe = filp->private_data; unsigned int head, tail; +#ifdef CONFIG_EPOLL /* Epoll has some historical nasty semantics, this enables them */ - WRITE_ONCE(pipe->poll_usage, true); + if ((filp->f_mode & FMODE_READ) && filp->f_ep) + WRITE_ONCE(pipe->poll_usage, true); +#endif /* * Reading pipe state only -- no need for acquiring the semaphore.
