xiaomi-sm8450/android_kernel_xiaomi_sm8450
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

pipe: Allow pipes to have kernel-reserved slots

Browse Source 
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>
This commit is contained in:
David Howells
2019-10-16 16:47:32 +01:00
parent 8cefc107ca
commit 6718b6f855
5 changed files with 30 additions and 24 deletions
Download Patch File Download Diff File Expand all files Collapse all files

8
fs/fuse/dev.c
View File

@@ -703,7 +703,7 @@ static int fuse_copy_fill(struct fuse_copy_state *cs)
cs->pipebufs++;
cs->nr_segs--;
} else {
if (cs->nr_segs >= cs->pipe->ring_size)
if (cs->nr_segs >= cs->pipe->max_usage)
return -EIO;
page = alloc_page(GFP_HIGHUSER);
@@ -879,7 +879,7 @@ static int fuse_ref_page(struct fuse_copy_state *cs, struct page *page,
struct pipe_buffer *buf;
int err;
if (cs->nr_segs >= cs->pipe->ring_size)
if (cs->nr_segs >= cs->pipe->max_usage)
return -EIO;
err = unlock_request(cs->req);
@@ -1341,7 +1341,7 @@ static ssize_t fuse_dev_splice_read(struct file *in, loff_t *ppos,
if (!fud)
return -EPERM;
bufs = kvmalloc_array(pipe->ring_size, sizeof(struct pipe_buffer),
bufs = kvmalloc_array(pipe->max_usage, sizeof(struct pipe_buffer),
GFP_KERNEL);
if (!bufs)
return -ENOMEM;
@@ -1353,7 +1353,7 @@ static ssize_t fuse_dev_splice_read(struct file *in, loff_t *ppos,
if (ret < 0)
goto out;
if (pipe_occupancy(pipe->head, pipe->tail) + cs.nr_segs > pipe->ring_size) {
if (pipe_occupancy(pipe->head, pipe->tail) + cs.nr_segs > pipe->max_usage) {
ret = -EIO;
goto out;
}