diff options
| author | David Howells <dhowells@redhat.com> | 2019-10-16 17:47:32 +0200 |
|---|---|---|
| committer | David Howells <dhowells@redhat.com> | 2019-11-15 17:22:54 +0100 |
| commit | 6718b6f855a0b4962d54bd625be2718cb820cec6 (patch) | |
| tree | 39d5e543cf914b26bdf4937b15d167c66c615f45 /lib/iov_iter.c | |
| parent | pipe: Use head and tail pointers for the ring, not cursor and length (diff) | |
| download | linux-6718b6f855a0b4962d54bd625be2718cb820cec6.tar.xz linux-6718b6f855a0b4962d54bd625be2718cb820cec6.zip | |
pipe: Allow pipes to have kernel-reserved slots
Split pipe->ring_size into two numbers:
(1) pipe->ring_size - indicates the hard size of the pipe ring.
(2) pipe->max_usage - indicates the maximum number of pipe ring slots that
userspace orchestrated events can fill.
This allows for a pipe that is both writable by the general kernel
notification facility and by userspace, allowing plenty of ring space for
notifications to be added whilst preventing userspace from being able to
pin too much unswappable kernel space.
Signed-off-by: David Howells <dhowells@redhat.com>
Diffstat (limited to 'lib/iov_iter.c')
| -rw-r--r-- | lib/iov_iter.c | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/lib/iov_iter.c b/lib/iov_iter.c index 957f8828378a..be2fc5793ddd 100644 --- a/lib/iov_iter.c +++ b/lib/iov_iter.c @@ -395,7 +395,7 @@ static size_t copy_page_to_iter_pipe(struct page *page, size_t offset, size_t by i_head++; buf = &pipe->bufs[i_head & p_mask]; } - if (pipe_full(i_head, p_tail, pipe->ring_size)) + if (pipe_full(i_head, p_tail, pipe->max_usage)) return 0; buf->ops = &page_cache_pipe_buf_ops; @@ -528,7 +528,7 @@ static size_t push_pipe(struct iov_iter *i, size_t size, pipe->bufs[iter_head & p_mask].len = PAGE_SIZE; iter_head++; } - while (!pipe_full(iter_head, p_tail, pipe->ring_size)) { + while (!pipe_full(iter_head, p_tail, pipe->max_usage)) { struct pipe_buffer *buf = &pipe->bufs[iter_head & p_mask]; struct page *page = alloc_page(GFP_USER); if (!page) |