io_uring/register: use atomic_read/write for sq_flags migration

[ Upstream commit a23ad06 ]

A previous commit changed all of the migration from the old to the new
ring for resizing to use READ/WRITE_ONCE. However, ->sq_flags is an
atomic_t, and while most archs won't complain on this, some will indeed
flag this:

io_uring/register.c:554:9: sparse: sparse: cast to non-scalar
io_uring/register.c:554:9: sparse: sparse: cast from non-scalar

Just use atomic_set/atomic_read for handling this case.

Reported-by: kernel test robot <[email protected]>
Closes: https://lore.kernel.org/oe-kbuild-all/[email protected]/
Fixes: 2c5aae1 ("io_uring/register: document io_register_resize_rings() shared mem usage")
Signed-off-by: Jens Axboe <[email protected]>
Signed-off-by: Sasha Levin <[email protected]>

Author: axboe

io_uring/register.c

@@ -553,7 +553,7 @@ static int io_register_resize_rings(struct io_ring_ctx *ctx, void __user *arg)
 	ctx->cqe_cached = ctx->cqe_sentinel = NULL;
 
 	WRITE_ONCE(n.rings->sq_dropped, READ_ONCE(o.rings->sq_dropped));
-	WRITE_ONCE(n.rings->sq_flags, READ_ONCE(o.rings->sq_flags));
+	atomic_set(&n.rings->sq_flags, atomic_read(&o.rings->sq_flags));
 	WRITE_ONCE(n.rings->cq_flags, READ_ONCE(o.rings->cq_flags));
 	WRITE_ONCE(n.rings->cq_overflow, READ_ONCE(o.rings->cq_overflow));