Re: [RFC PATCH 04/10] pipe: Use head and tail pointers for the ring, not cursor and length [ver #2]
flat view
From: Linus Torvalds <torvalds@linux-foundation.org>
Date: 2019-10-27 14:04:06
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This still has signs of that earlier series: On Wed, Oct 23, 2019 at 4:17 PM David Howells [off-list ref] wrote:
quoted hunk ↗ jump to hunk
if (rem >= ibuf->len) { *obuf = *ibuf; ibuf->ops = NULL; - pipe->curbuf = (pipe->curbuf + 1) & (pipe->buffers - 1); - pipe->nrbufs--; + tail++; + pipe_commit_read(pipe, tail); } else { if (!pipe_buf_get(pipe, ibuf)) goto out_free;
with those odd "pipe_commit_read/write()" helpers.
They make no sense, and they don't make things more legible.
It's shorter and more obvious to just write
pipe->head = head;
than it is to write
pipe_commit_write(pipe, head);
Even when the addition of the notifications, it's all under the
pipe->wait.lock, so it's all just regular assignments.
Now, if at some point it starts doing fancy lockless things, at _that_
point the updates might become more complex, but that's a potential
future thing that wouldn't be relevant for a while, and isn't a reason
to make the code more obscure now.
Hmm?
Linus