From: David Howells <dhowells@redhat.com>
To: Al Viro <viro@zeniv.linux.org.uk>
Cc: dhowells@redhat.com,
Linus Torvalds <torvalds@linux-foundation.org>,
Dan Williams <dan.j.williams@intel.com>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
linux-fsdevel <linux-fsdevel@vger.kernel.org>,
nvdimm@lists.linux.dev
Subject: Re: [RFC][PATCH] fix short copy handling in copy_mc_pipe_to_iter()
Date: Tue, 14 Jun 2022 07:36:19 +0100 [thread overview]
Message-ID: <1586153.1655188579@warthog.procyon.org.uk> (raw)
In-Reply-To: <Yqe6EjGTpkvJUU28@ZenIV>
Al Viro <viro@zeniv.linux.org.uk> wrote:
> What's wrong with
> p_occupancy = pipe_occupancy(head, tail);
> if (p_occupancy >= pipe->max_usage)
> return 0;
> else
> return pipe->max_usage - p_occupancy;
Because "pipe->max_usage - p_occupancy" can be negative.
post_one_notification() is limited by pipe->ring_size, not pipe->max_usage.
The idea is to allow some slack in a watch pipe for the watch_queue code to
use that userspace can't.
David
next prev parent reply other threads:[~2022-06-14 6:36 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-06-13 0:10 [RFC][PATCH] fix short copy handling in copy_mc_pipe_to_iter() Al Viro
2022-06-13 17:54 ` Linus Torvalds
2022-06-13 22:28 ` Al Viro
2022-06-13 23:25 ` Al Viro
2022-06-13 23:34 ` Al Viro
2022-06-14 0:53 ` Al Viro
2022-06-14 17:12 ` Al Viro
2022-06-14 6:36 ` David Howells [this message]
2022-06-14 12:11 ` Al Viro
2022-06-16 21:22 ` Dan Williams
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