Messages in this thread | | | From | Linus Torvalds <> | Date | Fri, 13 Jan 2017 12:08:44 -0800 | Subject | Re: 4.9.0 regression in pipe-backed iov_iter with systemd-nspawn |
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On Fri, Jan 13, 2017 at 11:33 AM, Linus Torvalds <torvalds@linux-foundation.org> wrote: > This function looks so broken that I must be missing something. Why > doesn't pipe_advance() just look like the following: > > static void pipe_advance(struct iov_iter *i, size_t size) > { ... > pipe_buf_release(pipe, buf); > pipe->nrbufs--; ...
I think this part needs to update "curbufs" too, so something like
pipe->curbuf = (pipe->curbuf + 1) & (pipe->buffers - 1);
although I think that "idx" has to track curbuf here anyway, so I guess it could just be combined with the idx update and look something like
pipe->curbuf = idx = next_idx(idx, pipe);
in there. Otherwise we get out of sync with the pipe state.
Or maybe I'm just full of it.
Linus
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