On Mon, Jan 28, 2019 at 10:35 PM Jens Axboe <axboe@xxxxxxxxx> wrote:
> The submission queue (SQ) and completion queue (CQ) rings are shared
> between the application and the kernel. This eliminates the need to
> copy data back and forth to submit and complete IO.
[...]
> +static int io_import_iovec(struct io_ring_ctx *ctx, int rw,
> + const struct io_uring_sqe *sqe,
> + struct iovec **iovec, struct iov_iter *iter)
> +{
> + void __user *buf = u64_to_user_ptr(sqe->addr);
> +
> +#ifdef CONFIG_COMPAT
> + if (in_compat_syscall())
> + return compat_import_iovec(rw, buf, sqe->len, UIO_FASTIOV,
> + iovec, iter);
> +#endif
> +
> + return import_iovec(rw, buf, sqe->len, UIO_FASTIOV, iovec, iter);
> +}
This code can run in kthread context, right? I think
in_compat_syscall() might not work if this is a kthread launched by a
compat task; I don't see anything that propagates the compat flag to
the kthread.
