Re: Regression: epoll edge-triggered (EPOLLET) for pipes/FIFOs

2020-10-13 Thread Michael Kerrisk (man-pages)
Hello Linus, On 10/13/20 12:30 AM, Linus Torvalds wrote: > On Mon, Oct 12, 2020 at 1:30 PM Michael Kerrisk (man-pages) > wrote: >> >> I don't think this is correct. The epoll(7) manual page >> sill carries the text written long ago by Davide Libenzi, >> the creator of epoll: >> >> Since

Re: Regression: epoll edge-triggered (EPOLLET) for pipes/FIFOs

2020-10-12 Thread Linus Torvalds
On Mon, Oct 12, 2020 at 1:30 PM Michael Kerrisk (man-pages) wrote: > > I don't think this is correct. The epoll(7) manual page > sill carries the text written long ago by Davide Libenzi, > the creator of epoll: > > Since even with edge-triggered epoll, multiple events can be gen‐ >

Re: Regression: epoll edge-triggered (EPOLLET) for pipes/FIFOs

2020-10-12 Thread Michael Kerrisk (man-pages)
On 10/12/20 10:52 PM, Linus Torvalds wrote: > On Mon, Oct 12, 2020 at 1:30 PM Michael Kerrisk (man-pages) > wrote: >> >> [CC += Davide] > > I'm not sure how active Davide is any more.. Yep, I know. But just in case. >> I don't think this is correct. The epoll(7) manual page >> sill carries the

Re: Regression: epoll edge-triggered (EPOLLET) for pipes/FIFOs

2020-10-12 Thread Randy Dunlap
On 10/12/20 1:52 PM, Linus Torvalds wrote: > On Mon, Oct 12, 2020 at 1:30 PM Michael Kerrisk (man-pages) > > I'm busy merging, mind testing this odd patch out? It is _entirely_ > untested, but from the symptoms I think it's the obvious fix. > > I did the same thing for the "reader starting out

Re: Regression: epoll edge-triggered (EPOLLET) for pipes/FIFOs

2020-10-12 Thread Linus Torvalds
On Mon, Oct 12, 2020 at 1:30 PM Michael Kerrisk (man-pages) wrote: > > [CC += Davide] I'm not sure how active Davide is any more.. > I don't think this is correct. The epoll(7) manual page > sill carries the text written long ago by Davide Libenzi, > the creator of epoll: > > Since even

Re: Regression: epoll edge-triggered (EPOLLET) for pipes/FIFOs

2020-10-12 Thread Michael Kerrisk (man-pages)
[CC += Davide] Hello Linus, Thanks for your quick reply. On 10/12/20 9:25 PM, Linus Torvalds wrote: > On Mon, Oct 12, 2020 at 11:40 AM Michael Kerrisk (man-pages) > wrote: >> >> Between Linux 5.4 and 5.5 a regression was introduced in the operation >> of the epoll EPOLLET flag. From some

Re: Regression: epoll edge-triggered (EPOLLET) for pipes/FIFOs

2020-10-12 Thread Linus Torvalds
On Mon, Oct 12, 2020 at 12:25 PM Linus Torvalds wrote: > > Now, the old pipe behavior was that it would wake up writers whether > they needed it or not [..] That "writers" should be "readers", of course. Although yes, that commit changed it for both readers and writers: if the pipe was readable

Re: Regression: epoll edge-triggered (EPOLLET) for pipes/FIFOs

2020-10-12 Thread Linus Torvalds
On Mon, Oct 12, 2020 at 11:40 AM Michael Kerrisk (man-pages) wrote: > > Between Linux 5.4 and 5.5 a regression was introduced in the operation > of the epoll EPOLLET flag. From some manual bisecting, the regression > appears to have been introduced in > > commit

Regression: epoll edge-triggered (EPOLLET) for pipes/FIFOs

2020-10-12 Thread Michael Kerrisk (man-pages)
Hello Linus, Between Linux 5.4 and 5.5 a regression was introduced in the operation of the epoll EPOLLET flag. From some manual bisecting, the regression appears to have been introduced in commit 1b6b26ae7053e4914181eedf70f2d92c12abda8a Author: Linus Torvalds Date: