From: Pavel Begunkov asml.silence@gmail.com
commit 976517f162a05f4315b2373fd11585c395506259 upstream.
There is a complaint against sys_io_uring_enter() blocking if it submits stdin reads. The problem is in __io_file_supports_async(), which sees that it's a cdev and allows it to be processed inline.
Punt char devices using generic rules of io_file_supports_async(), including checking for presence of *_iter() versions of rw callbacks. Apparently, it will affect most of cdevs with some exceptions like null and zero devices.
Cc: stable@vger.kernel.org Reported-by: Birk Hirdman lonjil@gmail.com Signed-off-by: Pavel Begunkov asml.silence@gmail.com Link: https://lore.kernel.org/r/d60270856b8a4560a639ef5f76e55eb563633599.162323645... Signed-off-by: Jens Axboe axboe@kernel.dk Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- fs/io_uring.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
--- a/fs/io_uring.c +++ b/fs/io_uring.c @@ -2770,7 +2770,7 @@ static bool io_file_supports_async(struc return true; return false; } - if (S_ISCHR(mode) || S_ISSOCK(mode)) + if (S_ISSOCK(mode)) return true; if (S_ISREG(mode)) { if (io_bdev_nowait(file->f_inode->i_sb->s_bdev) &&