From: Pavel Begunkov Date: Wed, 9 Jun 2021 11:07:25 +0000 (+0100) Subject: io_uring: fix blocking inline submission X-Git-Tag: v5.12.17~13 X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=4f4bc42d70e9e201bb0e58d16b2c6386e5fb93e8;p=thirdparty%2Fkernel%2Fstable.git io_uring: fix blocking inline submission 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 Signed-off-by: Pavel Begunkov Link: https://lore.kernel.org/r/d60270856b8a4560a639ef5f76e55eb563633599.1623236455.git.asml.silence@gmail.com Signed-off-by: Jens Axboe Signed-off-by: Greg Kroah-Hartman --- diff --git a/fs/io_uring.c b/fs/io_uring.c index 359d1abb089c4..c6e76c4fe706d 100644 --- a/fs/io_uring.c +++ b/fs/io_uring.c @@ -2683,7 +2683,7 @@ static bool io_file_supports_async(struct file *file, int rw) return true; return false; } - if (S_ISCHR(mode) || S_ISSOCK(mode)) + if (S_ISSOCK(mode)) return true; if (S_ISREG(mode)) { if (IS_ENABLED(CONFIG_BLOCK) &&