[PATCH] devpts: fix pty count limit off by one
Yichong Chen <[email protected]>
| Newsgroups | gmane.linux.kernel,gmane.linux.serial |
|---|---|
| Message-ID | <[email protected]> |
devpts_new_index() increments the global pty count before checking it
against the effective global limit. The check currently rejects a new pty
when the incremented count is equal to the limit.
This makes kernel.pty.max allow only max - 1 ptys. For example, if
kernel.pty.nr is 3 and kernel.pty.max is set to 4, opening /dev/ptmx
fails with -ENOSPC even though one more pty should be allowed.
Allow the incremented count to be equal to the effective limit and reject
only counts above it.
Fixes: 0f0a0e54a2a1 ("devpts: Convert to new IDA API")
Signed-off-by: Yichong Chen <[email protected]>
---
fs/devpts/inode.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/fs/devpts/inode.c b/fs/devpts/inode.c
index 9844dcf354ee..853cc4c03e73 100644
--- a/fs/devpts/inode.c
+++ b/fs/devpts/inode.c
@@ -467,7 +467,7 @@ int devpts_new_index(struct pts_fs_info *fsi)
{
int index = -ENOSPC;
- if (atomic_inc_return(&pty_count) >= (pty_limit -
+ if (atomic_inc_return(&pty_count) > (pty_limit -
(fsi->mount_opts.reserve ? 0 : pty_reserve)))
goto out;
--
2.51.0