[PATCH 5.9 14/74] io_uring: Fix use of XArray in __io_uring_files_cancel

Greg Kroah-Hartman
2020-10-31T11:48:56Z

From: "Matthew Wilcox (Oracle)" <willy@infradead.org>

commit ce765372bc443573d1d339a2bf4995de385dea3a upstream.

We have to drop the lock during each iteration, so there's no advantage
to using the advanced API. Convert this to a standard xa_for_each() loop.

Reported-by: syzbot+27c12725d8ff0bfe1a13@syzkaller.appspotmail.com
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
fs/io_uring.c | 19 +++++--------------
1 file changed, 5 insertions(+), 14 deletions(-)

--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -8415,28 +8415,19 @@ static void io_uring_attempt_task_drop(s
void __io_uring_files_cancel(struct files_struct *files)
{
struct io_uring_task *tctx = current->io_uring;
- XA_STATE(xas, &tctx->xa, 0);
+ struct file *file;
+ unsigned long index;

/* make sure overflow events are dropped */
tctx->in_idle = true;

- do {
- struct io_ring_ctx *ctx;
- struct file *file;
-
- xas_lock(&xas);
- file = xas_next_entry(&xas, ULONG_MAX);
- xas_unlock(&xas);
-
- if (!file)
- break;
-
- ctx = file->private_data;
+ xa_for_each(&tctx->xa, index, file) {
+ struct io_ring_ctx *ctx = file->private_data;

io_uring_cancel_task_requests(ctx, files);
if (files)
io_uring_del_task_file(file);
- } while (1);
+ }
}

static inline bool io_uring_task_idle(struct io_uring_task *tctx)